DOE-HDBK-1092-2013, Electrical Safety

NOT MEASUREMENT SENSITIVE DOE HANDBOOK ELECTRICAL SAFETY DOE-HDBK-1092-2013 July 2013 Superseding DOE-HDBK-1092-2004 December 2004 U.S. Department of Energy AREA SAFT Washington, D.C.20585 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. DOE-HDBK-1092-2013 Available on the Department of Energy Technical Standards Program Web site at http://www.hss.doe.gov/nuclearsafety/techstds/ ii http://www.hss.doe.gov/nuclearsafety/techstds DOE-HDBK-1092-2013 FOREWORD 1. This Department of Energy (DOE) Handbook is approved for use by the Office of Health, Safety and Security and is available to all DOE components and their contractors. 2. Specific comments (recommendations, additions, deletions, and any pertinent data) to enhance this document should be sent to: Patrick Tran HS-12/Germantown U.S. Department of Energy 1000 Independence Ave. SW Washington, DC 20585-0270 3. This DOE Electrical Safety Handbook replaces the DOE Electrical Safety Handbook that was originally issued in 1998, and revised in 2004. DOE handbooks are part of the DOE directives system and are issued to provide supplemental information regarding the Department's expectations for fulfilling its requirements as contained in rules, orders, notices, and regulatory standards. The handbooks may also provide acceptable methods for implementing those requirements. Handbooks are not substitutes for requirements, nor do they replace technical standards that are used to describe established practices and procedures for implementing requirements. 4. This updated handbook contains DOE-developed explanatory material in support of national electrical safety codes and standards, including those referenced in the Code of Federal Regulations (CFR) in 10 CFR 851, Worker Safety and Health Program. Sections of this handbook were revised and relocated within the handbook for improved clarity of information. This document references the most recent version of each code and standard at the time of development, recognizing that newer versions are invariably improved and provide increased safety over previous versions. 10 CFR 851 references the 2005 edition of the National Fire Protection Association (NFPA) 70, the National Electrical Code (NEC), and the 2004 edition of the Standard for Electrical Safety in the Workplace (NFPA 70E). This document, however, references the 2008 NEC and the 2009 NFPA 70E versions. Each site must ensure, through review, that its implementation of the newer versions meets the intent of 10 CFR 851. In addition other electrical codes and standards utilized in this handbook include: 29 CFR 1910, Subpart S, Occupational Safety and Health Standards, Electrical; 29 CFR 1926 Subpart K, Safety and Health Regulations for Construction, Electrical; IEEE/ANSI Std C2, National Electrical Safety Code (2007); NFPA 70B, Recommended Practice for Electrical Equipment Maintenance (2010); and others. For a complete list of references used in this document, see Section 14. iii                                                                                                                                                                         DOE-HDBK-1092-2013 CONTENTS 1.0 INTRODUCTION 1 1.1 PURPOSE ........................................................................................................................................ 1

1.2 SCOPE ............................................................................................................................................. 1 1.3 ELECTRICAL SAFETY PROGRAM ................................................................................................ 2 1.4 AUTHORITY HAVING JURISDICTION ........................................................................................... 2 2.0 GENERAL REQUIREMENTS 4 2.1 ELECTRICAL MAINTENANCE OR REPAIRS ................................................................................ 4 2.1.1 Work on Electrical Equipment .............................................................................................4 2.1.2 Considerations for Working on Energized Systems and Equipment .................................. 4 2.1.3 Safety Watch Responsibilities and Qualifications ...............................................................5 2.2 BASIC SAFEGUARDS..................................................................................................................... 5 2.3 RESPONSIBILITIES ........................................................................................................................ 6 2.3.1 Management Responsibilities ............................................................................................. 6 2.3.2 Employee Responsibilities .................................................................................................. 7 2.4 MODIFICATIONS TO FACILITIES .................................................................................................. 7 2.5 APPROVAL OF ELECTRICAL EQUIPMENT .................................................................................. 7 2.6 CODES, STANDARDS, AND REGULATIONS................................................................................ 7 2.7 TRAINING AND QUALIFICATIONS OF QUALIFIED WORKERS .................................................. 8 2.7.1 Formal Training and Qualifications .....................................................................................8 2.7.2 Training of Safety Personnel ............................................................................................... 9 2.8 WORKING SPACE AROUND ELECTRICAL EQUIPMENT ............................................................ 9 2.8.1 Electrical Equipment Rated at 600 Volts or Less ................................................................9 2.8.2 Electrical Equipment Rated over 600 Volts ...................................................................... 11 2.9 IDENTIFICATION OF DISCONNECTING MEANS ....................................................................... 12 2.9.1 Disconnecting Means ........................................................................................................12 2.9.2 Panelboard Circuit Directories ..........................................................................................12 2.9.3 Enclosure Labeling............................................................................................................12 2.9.4 Load Labeling .................................................................................................................... 12 2.9.5 Source Labeling ................................................................................................................ 12 2.10 WORK INSTRUCTIONS ................................................................................................................ 13

2.10.1 Safe Work Instructions and Supervision ...........................................................................13 2.10.2 Work Planning ................................................................................................................... 13 2.11 ELECTRICAL PERSONAL PROTECTIVE EQUIPMENT .............................................................. 14 2.11.1 Management's Responsibilities......................................................................................... 14 2.11.2 Inspecting PPE .................................................................................................................. 14 2.11.3 Cleaning and Electrical Testing of PPE ............................................................................14 2.11.4 Live-Line Tools .................................................................................................................. 15 2.11.5 Fiberglass-Handled Tools ................................................................................................. 15 2.11.6 Maximum-Use Alternating Current (AC) Voltage .............................................................. 15 2.11.7 Maximum Usage Voltage for Live-Line Tools ................................................................... 15 2.11.8 Rubber-Insulated Gloves .................................................................................................. 16 2.11.9 Storage.............................................................................................................................. 16 2.11.10 Safety Shoes, Hardhats, and Glasses .............................................................................. 16 iv                                                                                                                                                                                 DOE-HDBK-1092-2013 2.12 WORK PRACTICES ...................................................................................................................... 16 2.12.1 Establishing an Electrically-Safe Work Condition .............................................................16 2.12.2 Training ............................................................................................................................. 19 2.12.3 Planning the Work ............................................................................................................. 19 2.12.4 Personal Protective Equipment .........................................................................................23 2.12.5 Electrical Injuries ............................................................................................................... 23 3.0 Hazard Analysis 24 4.0 ELECTRICAL PREVENTIVE MAINTENANCE 25 4.1 DEVELOPMENT AND IMPLEMENTATION REQUIREMENTS .................................................... 25 4.2 ELECTRICAL PREVENTIVE MAINTENANCE PROGRAM .......................................................... 25 4.3 MAINTENANCE ............................................................................................................................. 25 4.4 INSPECTION ................................................................................................................................. 25 4.5 ESSENTIAL ELEMENTS ............................................................................................................... 26

4.6 PLANNING AND DEVELOPING AN EPM PROGRAM, AND FUNDAMENTALS OF EPM .......... 26 4.7 GROUND FAULT PROTECTION AND ARC FAULT CIRCUIT INTERRUPTERS ....................... 26 4.7.1 Ground Fault Circuit Interrupters (GFCIs).........................................................................27 4.7.2 Arc Fault Circuit Interrupters (AFCIs) ................................................................................28 4.7.3 Ground Fault Protection for Equipment (GFPE) ...............................................................29 4.8 OVERCURRENT PROTECTIVE DEVICES .................................................................................. 29 5.0 GROUNDING 30 5.1 SPECIFICATIONS AND DRAWINGS............................................................................................ 30 5.2 CIRCUIT AND SYSTEM GROUNDING ......................................................................................... 30 5.3 EQUIPMENT GROUNDING .......................................................................................................... 30 5.4 BONDING ...................................................................................................................................... 31 5.5 GROUNDED OR UNGROUNDED SYSTEMS .............................................................................. 32 5.5.1 Grounded Systems ...........................................................................................................33 5.5.2 Ungrounded Systems .......................................................................................................34 5.5.3 High-Impedance Grounding .............................................................................................. 35 5.6 GROUNDING REQUIREMENTS ................................................................................................... 36 5.7 GROUNDING ELECTRODE CONDUCTOR (GEC) ...................................................................... 37 5.7.1 Sizing the Grounding Electrode Conductor ...................................................................... 38 5.7.2 Exceptions to NEC 250.66 ................................................................................................38 5.8 MAIN BONDING JUMPER............................................................................................................. 38 5.9 SYSTEM WITH GROUNDED CONDUCTOR ................................................................................ 39 5.10 EQUIPMENT GROUNDING CONDUCTOR .................................................................................. 40 5.10.1 Sizing the Equipment Grounding Conductor .................................................................... 41 5.10.2 Separate Equipment Grounding Conductors .................................................................... 41 5.11 UNGROUNDED SYSTEMS ........................................................................................................... 41 5.12 GROUNDING A SEPARATELY DERIVED SYSTEM .................................................................... 42 5.13 GROUNDING ELECTRODE SYSTEM .......................................................................................... 42 5.14 PERSONNEL PROTECTIVE GROUNDS ..................................................................................... 43 5.14.1 Purpose of Personnel Protective Grounds .......................................................................44

5.14.2 Criteria for Personnel Protective Grounds ........................................................................44 5.14.3 Grounding Clamps ............................................................................................................45 v                                                                                                                                                                                 DOE-HDBK-1092-2013 5.14.4 Screw-Tightening Devices ................................................................................................ 45 5.14.5 Grounding Cable Length ................................................................................................... 45 5.14.6 Grounding Cable Connection ............................................................................................ 45 5.14.7 Connecting Grounding Cables in Sequence..................................................................... 45 5.14.8 Removing Protective Grounds ..........................................................................................45 5.14.9 Protective Apparel and Equipment ...................................................................................45 6.0 SPECIAL OCCUPANCIES 47 6.1 EXPLOSIVES ................................................................................................................................. 47 6.1.1 Evacuation ........................................................................................................................ 47 6.1.2 Shutdown of Operations ................................................................................................... 47 6.1.3 Lightning Protection .......................................................................................................... 47 6.1.4 Static Electricity................................................................................................................. 48 6.1.5 Electrical Equipment and Wiring ....................................................................................... 51 6.1.6 Testing .............................................................................................................................. 53 6.2 PREVENTION OF EXTERNAL IGNITION AND EXPLOSION ...................................................... 57 6.2.1 Sources of Ignition ............................................................................................................ 58 6.2.2 Combustion Principles ......................................................................................................58 6.2.3 Evaluation of Hazardous Areas ........................................................................................ 59 6.2.4 Intrinsically Safe Equipment ..............................................................................................59 6.2.5 Enclosures ........................................................................................................................ 59 6.2.6 Purging/Pressurization Systems .......................................................................................61 6.3 HAZARDOUS LOCATIONS........................................................................................................... 62 6.3.1 Class I ............................................................................................................................... 62

6.3.2 Class II .............................................................................................................................. 66 6.3.3 Groups .............................................................................................................................. 68 6.3.4 Ignition Temperature .........................................................................................................68 6.3.5 Flammable (Explosion) Limits ........................................................................................... 68 6.3.6 Flashpoint .......................................................................................................................... 69 6.4 ELECTRICAL EQUIPMENT FOR CLASS I, II, AND III AREAS.................................................... 69 6.4.1 Seals and Drains ............................................................................................................... 69 6.5 DESCRIPTIONS, FEATURES, AND TEST CRITERIA OF ENCLOSURES FOR HAZARDOUS (CLASSIFIED) LOCATIONS (PER NEMA 250) ...................................................................................... 71 6.5.1 Type 7 Enclosures ............................................................................................................72 6.5.2 Type 8 Enclosures ............................................................................................................72 6.5.3 Type 9 Enclosures ............................................................................................................73 6.6 UNDERGROUND FACILITIES ...................................................................................................... 74 6.6.1 Work on Electrical Equipment and Circuits ....................................................................... 75 6.6.2 Power Cables and Conductors .........................................................................................75 6.6.3 Trailing Cables .................................................................................................................. 76 6.6.4 Trolley Circuits for Track Haulage.....................................................................................76 7.0 REQUIREMENTS FOR SPECIFIC EQUIPMENT 77 7.1 CONVEYING SYSTEMS ............................................................................................................... 77 7.1.1 Electrical Design Criteria ...................................................................................................77 7.2 CRANES AND HOISTS ................................................................................................................. 78 7.2.1 NEC General Requirements .............................................................................................78 vi                                                                                                                                                                                 DOE-HDBK-1092-2013 7.2.2 Disconnecting Means ........................................................................................................78 7.2.3 Grounding ......................................................................................................................... 80 7.2.4 Control............................................................................................................................... 80

7.2.5 Clearances ........................................................................................................................ 80 7.2.6 OSHA and NEC Requirements .........................................................................................80 7.2.7 Maintenance and Operations ............................................................................................80 7.2.8 Documented Maintenance ................................................................................................ 81 7.2.9 Mechanical Elevating and Rotating Equipment ................................................................81 7.3 ELEVATORS AND ESCALATORS ................................................................................................ 82 7.3.1 Codes and Standards ....................................................................................................... 82 7.3.2 Design Specifications ........................................................................................................82 7.3.3 Emergency Power ............................................................................................................. 84 7.3.4 Design ............................................................................................................................... 84 7.3.5 Fire Protection ................................................................................................................... 85 7.3.6 Inspections and Records .................................................................................................. 85 7.4 PORTABLE AND VEHICLE-MOUNTED GENERATORS ............................................................. 85 7.4.1 Ground Fault Circuit Interrupter ........................................................................................86 7.4.2 Grounding Portable and Vehicle-Mounted Generators ..................................................... 86 7.5 BATTERIES ................................................................................................................................... 86 7.5.1 Surrounding Space ........................................................................................................... 86 7.5.2 Location............................................................................................................................. 86 7.5.3 Ventilation ......................................................................................................................... 87 7.5.4 Conduit .............................................................................................................................. 87 7.5.5 Battery Room .................................................................................................................... 87 7.5.6 Personal Protective Equipment .........................................................................................88 7.5.7 Tools ................................................................................................................................. 88 7.5.8 Storage Batteries and Battery Banks ................................................................................ 88 8.0 WORK IN EXCESS OF 600 VOLTS 91 8.1 RESPONSIBILITIES FOR SAFETY .............................................................................................. 91 8.1.1 Workers ............................................................................................................................. 91

8.1.2 Supervisors ....................................................................................................................... 92 8.2 TRAINING ...................................................................................................................................... 92 8.2.1 Employee Training ............................................................................................................92 8.2.2 Qualified Employee Training .............................................................................................93 8.3 JOB BRIEFINGS............................................................................................................................ 93 8.4 PERSONAL PROTECTIVE EQUIPMENT AND PROTECTIVE CLOTHING ................................ 94 8.4.1 Shoes ................................................................................................................................ 94 8.4.2 Hardhats ............................................................................................................................ 94 8.4.3 Eye Protectors................................................................................................................... 95 8.4.4 Conductive Articles ........................................................................................................... 95 8.4.5 Work Gloves...................................................................................................................... 95 8.4.6 Work Clothes..................................................................................................................... 95 8.4.7 Fire-Resistant (FR) Arc-Rated (AR) Clothing ................................................................... 95 8.4.8 Rubber Gloves .................................................................................................................. 96 vii                                                                                                                                                                                 DOE-HDBK-1092-2013 8.4.9 Rubber Line Hose, Hoods, Covers, Sleeves, and Blankets ............................................. 97 8.4.10 Live Line Tools .................................................................................................................. 97 8.4.11 Storeroom Storage ............................................................................................................97 8.4.12 Truck Storage .................................................................................................................... 97 8.4.13 Placing of Insulating Goods on Conductors ...................................................................... 98 8.4.14 Removing Insulating Goods from Conductors .................................................................. 98 8.4.15 Cleaning and Inspecting ...................................................................................................98 8.5 PROTECTIVE GROUNDING OF LINES AND EQUIPMENT ........................................................ 98 8.5.1 Purpose ............................................................................................................................. 98 8.5.2 Application ......................................................................................................................... 99

8.5.3 Grounding Equipment .....................................................................................................101 8.5.4 Testing Before Installing Grounds ...................................................................................104 8.5.5 Attaching and Removing Grounds ..................................................................................104 8.5.6 Grounding Methods and Location of Grounds in Order of Preference ...........................105 8.5.7 Testing Without Grounds ................................................................................................105 8.5.8 Ground Personnel ...........................................................................................................105 8.6 INSTALLING OR REMOVING CONDUCTORS .......................................................................... 106 8.6.1 Working on Energized Line or Equipment ......................................................................106 8.6.2 Stringing or Removing De-energized Conductors ..........................................................106 8.6.3 Stringing Adjacent to Energized Lines ............................................................................108 8.7 SPECIAL TOOLS ......................................................................................................................... 108 8.7.1 Lineworkers’ Climbing Tools ...........................................................................................109 8.7.2 Body Belts and Safety Straps .........................................................................................110 8.7.3 Tool Bag and Equipment ................................................................................................110 8.7.4 Tapes and Rulers ............................................................................................................110 8.7.5 Spoon and Shovels .........................................................................................................110 8.7.6 Pike Poles ....................................................................................................................... 110 8.7.7 Hand Axes and Sharp Tools ...........................................................................................110 8.7.8 Handlines and Taglines ..................................................................................................110 8.8 TREE TRIMMING ........................................................................................................................ 111 8.8.1 Care and Use of Tools ....................................................................................................111 8.8.2 Climbing .......................................................................................................................... 111 8.9 UNDERGROUND ........................................................................................................................ 111 8.9.1 Working in Manholes, Utility Tunnels, and Vaults ...........................................................111 8.9.2 Working on Energized Underground Cables ..................................................................113 8.9.3 Terminals of Underground Cables (Potheads) ...............................................................113 8.10 FERRO-RESONANCE................................................................................................................. 113

9.0 TEMPORARY WIRING 115 9.1 REQUIREMENTS AND INSTALLATION CONDITIONS OF USE ............................................... 115 9.1.1 Contact Prevention..........................................................................................................115 9.1.2 Vertical Clearances .........................................................................................................115 9.1.3 Wet Locations ................................................................................................................. 115 9.1.4 Bushings ......................................................................................................................... 115 9.1.5 Lighting............................................................................................................................ 115 viii                                                                                                                                                                                 DOE-HDBK-1092-2013 9.1.6 Confined Spaces .............................................................................................................116 9.1.7 Exposed Sockets and Broken Bulbs ...............................................................................116 9.1.8 Ground Fault Protection for Personnel ...........................................................................116 9.1.9 Wiring Methods ...............................................................................................................116 9.2 Using Assured Equipment Grounding Conductor Program......................................................... 117 9.3 PORTABLE ELECTRICAL TOOLS AND EQUIPMENT .............................................................. 118 9.3.1 Inspection and Maintenance ...........................................................................................118 9.3.2 Conditions of Use ............................................................................................................119 9.3.3 Use of Extension Cords ..................................................................................................119 9.3.4 Double Insulated Tools ...................................................................................................119 10.0 ELECTRICAL SAFETY DURING EXCAVATION 121 10.1 GENERAL .................................................................................................................................... 121 10.2 UTILITIES IDENTIFICATION ....................................................................................................... 121 10.2.1 Configuration Management .............................................................................................121 10.2.2 Excavation Permit ...........................................................................................................122 10.3 UTILITIES VERIFICATION AND MARKING ................................................................................ 122 10.3.1 Field Location of Excavation Boundaries ........................................................................122 10.3.2 Locator Equipment Selection and Limitations .................................................................123 10.3.3 Locator Operator Training ...............................................................................................124

10.3.4 Field Marking of Identified Utilities ..................................................................................125 10.4 UTILITIES DISPOSITION ............................................................................................................ 125 10.5 WORK CONTROL DURING EXCAVATIONS ............................................................................. 125 10.5.1 Safety Equipment and Procedures .................................................................................125 10.6 THE EXCAVATION PROCESS ................................................................................................... 125 10.6.1 Excavations in Concrete Walls and Slabs ......................................................................126 10.6.2 Machine or Hand Digging ...............................................................................................126 10.7 AS-BUILT DRAWINGS ................................................................................................................ 127 11.0 ENCLOSED ELECTRICAL/ELECTRONIC EQUIPMENT 128 11.1 GROUNDING AND BONDING .................................................................................................... 128 11.1.1 Objectionable Current over Grounding Conductors ........................................................128 11.1.2 Enclosure Equipment Grounding and Bonding ...............................................................129 11.2 RACK POWER DISTRIBUTION .................................................................................................. 132 11.2.1 General Requirements Applying to All AC Power Equipment within or Attached to Instrument Racks ............................................................................................................132 11.2.2 Conductors, Cords and Cables Specific Requirements..................................................132 11.2.3 Power Switches and Interlock Devices Specific Requirements ......................................134 11.3 CHASSIS POWER DISTRIBUTION ............................................................................................ 134 11.3.1 AC Power Distribution .....................................................................................................135 11.3.2 DC Power Distribution .....................................................................................................136 11.4 PROTECTIVE DEVICES FOR ENCLOSED ELECTRICAL/ ELECTRONIC EQUIPMENT ........ 136 11.4.1 Surge Arresters ............................................................................................................... 136 11.4.2 Fuses .............................................................................................................................. 136 11.4.3 Circuit Breakers ...............................................................................................................137 11.4.4 Power Interlock Devices .................................................................................................137 11.5 DISCONNECTING MEANS ......................................................................................................... 137 ix                                                                                                                                                                                 DOE-HDBK-1092-2013

11.5.1 General ........................................................................................................................... 137 11.5.2 Emergency Shutdown .....................................................................................................138 11.5.3 Special Considerations ...................................................................................................138 11.6 MARKING AND LABELING REQUIREMENTS ........................................................................... 138 11.6.1 General Marking Requirements ......................................................................................138 11.6.2 Hazard Marking Requirements .......................................................................................138 11.6.3 Other Requirements ........................................................................................................138 11.7 WORKING CLEARANCE............................................................................................................. 139 11.8 CABLE/UTILITY MANAGEMENT SYSTEM ................................................................................ 140 11.8.1 Usage with Enclosed Electrical/Electronic Equipment....................................................140 11.8.2 Requirements .................................................................................................................. 141 11.9 ELECTRICAL SAFETY REQUIREMENTS FOR TESTER FACILITIES ..................................... 143 11.9.1 Ampacity of Facility Wiring and Distribution Equipment .................................................143 11.9.2 Facility Grounding at Temporary or Remote Sites ..........................................................143 11.9.3 Facility Lightning Protection ............................................................................................144 11.9.4 Surge Protection .............................................................................................................144 11.10ENCLOSED POWER ELECTRONICS ........................................................................................ 144 11.10.1 Enclosures ...................................................................................................................... 144 11.10.2 Component Clearances ..................................................................................................144 11.10.3 Instrumentation ............................................................................................................... 145 11.10.4 General ........................................................................................................................... 145 11.11NON-IONIZING RADIATION ....................................................................................................... 145 11.11.1 Electromagnetic Radiation ..............................................................................................145 11.11.2 Electromagnetic Radiation Threat to Electro Explosive Devices ....................................146 11.12AMPACITY INFORMATION FOR WIRE SIZING ........................................................................ 147 11.12.1 Ampacity Information ......................................................................................................147 11.12.2 Color Coding Guidelines .................................................................................................148

12.0 APPROVAL OF UNLISTED ELECTRICAL EQUIPMENT 151 13.0 RESEARCH & DEVELOPMENT 152 13.1 OPERATION AND MAINTENANCE ............................................................................................ 152 13.2 EMPLOYEE QUALIFICATIONS .................................................................................................. 152 13.2.1 Hazards ........................................................................................................................... 152 13.2.2 Additional Qualifications ..................................................................................................153 13.3 GENERIC R&D EQUIPMENT ...................................................................................................... 153 13.3.1 Power Sources ................................................................................................................153 13.3.2 Conditions of Low-Voltage and High-Current .................................................................154 13.3.3 Conditions of High-Voltage and Low-Current .................................................................155 13.3.4 Radio-Frequency/Microwave Radiation and Fields ........................................................156 13.4 METHODS ................................................................................................................................... 158 13.4.1 Wiring Methods ...............................................................................................................158 13.4.2 Unconventional Practices ...............................................................................................159 13.4.3 Work on Energized or De-Energized Electrical Equipment ............................................166 13.5 REQUIREMENTS FOR SPECIFIC R&D EQUIPMENT ............................................................... 166 13.5.1 Capacitors ....................................................................................................................... 167 x                                     DOE-HDBK-1092-2013 13.5.2 Inductors ......................................................................................................................... 170 13.5.3 Electrical Conductors and Connectors ............................................................................171 13.5.4 Induction and Dielectric Heating Equipment ...................................................................172 13.5.5 Batteries .......................................................................................................................... 173 13.5.6 Lasers and X-Ray Equipment .........................................................................................177 14.0 REFERENCES 179 APPENDIX A DOE MODEL ELECTRICAL SAFETY PROGRAM A-1 APPENDIX B ACRONYMS AND DEFINITIONS B-1 APPENDIX C EXAMPLE PROGRAM FOR UNLISTED ELECTRICAL EQUIPMENT C-1 APPENDIX D HAZARD ANALYSIS D-1 APPENDIX E REFERENCED REGULATION CITATIONS E-1 APPENDIX F EXAMPLE OF A WAY TO MEASURE ELECTRICAL SEVERITY F-1 xi DOE-HDBK-1092-2013 1.0 INTRODUCTION

Generally, the guidance contained in this Department of Energy (DOE) Handbook for Electrical Safety, DOE-HDBK-1092-2013, for implementing electrical safety at DOE facilities is based on well-developed industrial practices, mandatory rules, or nationally-recognized consensus codes or standards. The guidelines are written to be flexible, so that they encompass the range from large, permanent DOE test or production facilities to small research or testing facilities. These guidelines form a compendium of good practices and describe key elements of programs that support electrical safety at DOE facilities. Implementation of these guidelines should result in a high level of performance and, therefore, contribute to safe work practices and work places that reduce the risk of exposure to electrical hazards for both people and property. Experience has shown that better performing facilities have well-defined, effectively-administered policies and programs to govern the activities of the people responsible for maintaining an electrically-safe workplace. These guidelines have, therefore, been prepared to assist facilities in the review and development of programs important to electrical safety. These guidelines have been written to assist facilities in meeting performance and safety objectives related to electrical hazard reduction. It is intended that these guidelines be used to review existing or planned programs or facilities and to develop programs where none presently exist. It is expected that facilities may use different approaches or methods than those defined in the guidelines. Some expansion of the intent of the guidelines is provided in the introduction and discussion sections of each section, and the specific guidelines that follow reflect generally accepted methods for conducting an effective electrical safety program. Deviation from any particular guideline would not, in itself, indicate a programmatic problem. However, differences between the guidelines and actual practices should be reviewed to determine if a facility practice should be changed. A change in facility practice would be appropriate if a performance weakness is determined to exist. It is recognized that these guidelines cross into areas covered by multiple electrical safety references. During the development of this Handbook, no specific guidance was found to be in conflict with other DOE directives. If a user finds any conflicts, the matter should be resolved by bringing the issue to the attention of DOE’s Office of Health, Safety and Security, Office of Worker Safety and Health Assistance, HS-12. 1.1 PURPOSE The purpose of this Handbook is to present DOE’s safety standards for its field offices or facilities involved in the use of electrical energy. It has been prepared to provide a uniform set of electrical safety guidance and information to assist DOE organizations in efforts to effect a reduction or elimination of risks associated with the use of electrical energy. The objectives of this Handbook are to enhance electrical safety awareness and mitigate electrical hazards to employees, the public, and the environment. This Handbook does not supersede any existing standards or laws. Rather, this document offers methodologies that augment and support the intended safety objectives of applicable codes and standards.

1.2 SCOPE This Handbook provides general information to enhance understanding of DOE orders (O), national codes, national standards, and local, state, and federal regulations. Each user should reference their contract document(s) and determine what legal requirements are to be followed in the area of electrical safety. These requirements and the implementing mechanisms may 1 DOE-HDBK-1092-2013 vary by location. In other than the appendices of this document, "shall" refers to requirements of regulatory standards identified in the Code of Federal Regulations (CFR) in 10 CFR 851, Worker Health and Safety Program, that may or may not apply to a specific location (e.g. Southwestern Power Administration, Western Area Power Administration, Bonneville, etc.). Regulations designated by “shall” are referenced by superscript to the appropriate citation listed in Appendix E. "Should" refers to guidance from consensus standards that may not apply contractually, or to practices in use at various DOE sites. Where there are multiple references that reflect a particular rule, in some cases only one of the references is cited. References to the National Fire Protection Association’s (NFPA) NFPA 70, National Electric Code (NEC), are taken from the 2008 edition. References to NFPA 70E, Standard for Electrical Safety in the Workplace, are taken from the 2009 edition. References to Occupational Safety and Health Administration (OSHA) regulations are taken from the 2007 edition. Appendices provide references, examples, definitions, and other information that enhances the material found in the body of the document. The design of new facilities should conform to relevant DOE orders and industry-recognized engineering design standards. Existing facilities should evaluate their systems and operations in relation to this Handbook, applicable DOE orders, national codes, national standards, and local, state, and federal regulations to determine if they comply or if a safety problem exists. If the evaluation determines that an unacceptable risk of exposure to an imminent hazard exists, corrective actions should be initiated, including consideration to bring the systems or operations into compliance with current standards. In the case of a major renovation of an existing facility, the modification shall1.1 comply with current standards. Existing facilities shall1.2 conform to 10 CFR 851, which permits compliance with an existing code of record and relevant DOE orders. The OSHA standards have specific requirements that shall1.3 apply to all electrical installations and utilization equipment, regardless of when they were designed or installed, and identify other mandatory provisions and specify effective dates. Installations in compliance with the code at the time of design or installation (code of record), do not need to be upgraded to the updated code unless required to correct a known hazard or a major modification is being performed. 1.3 ELECTRICAL SAFETY PROGRAM Each DOE site shall1.4 establish an electrical safety program that meets the requirements of 10 CFR 851. Electrical safety programs should institute elements described in Appendix A “DOE Model Electrical Safety Program” of this Handbook. Electrical safety requirements shall1.5 flow down to all appropriate contractors and lower-tiered subcontractors and vendors.

1.4 AUTHORITY HAVING JURISDICTION In states and municipalities, an organization (electrical safety committee or board) or official (electrical inspector, engineer, or equivalent qualified individual) is usually designated as the electrical Authority Having Jurisdiction (AHJ). The AHJ should possess such executive ability as is required for performance of the position, and should have thorough knowledge of standard materials and work practices used in the installation, operation, construction, and maintenance of electrical equipment. The AHJ should, through experience or education, be knowledgeable of the requirements contained in 10 CFR 851, OSHA standards, the Institute of Electrical and Electronic Engineers’ (IEEE) National Electrical Safety Code (NESC) (IEEE/ANSI C-2), NFPA 70, NFPA 70E, DOE requirements, and other appropriate local, state, and national standards. The AHJ should be responsible to interpret codes, regulations and standards, and approve 2 DOE-HDBK-1092-2013 equipment, assemblies, or materials. If the AHJ needs to address items outside their electrical expertise, such as fire, confined space, fall protection, or like issues, the AHJ should consult with cognizant experts before a decision is reached. The AHJ may permit alternate methods when it is assured that equivalent objectives can be achieved by establishing and maintaining effective safety equal to, or exceeding, established codes, regulations, and standards. In DOE, levels of authority exist that serve the function of the AHJ. The AHJ may be the contracting officer, such as an area manager. This person may choose to delegate authority to an individual or organization within their control. It is acceptable for DOE sites to delegate authority to an appropriate committee (refer to Appendix A “DOE Model Electrical Safety Program” of this Handbook). The authority may reside with a safety or facilities department. The field office manager or designated representative may act as a higher level of authority. Per the Integrated Safety Management model, responsibility for electrical safety continues down to all workers. Figure 1-1 illustrates a typical AHJ and worker responsibility hierarchy. DOE contractors should establish lines of authority within their organizations. It is important that a line of authority be established, documented, and recognized. Formal delegation should be obtained from the responsible DOE field office. The limits of the authority and recognition of a higher authority should be delineated. DOE, as the governing agency, is the ultimate authority for all decisions regarding mandatory electrical codes and standards. Fig. 1-1. Flow down of Electrical AHJ and worker responsibility. 3 DOE-HDBK-1092-2013 2.0 GENERAL REQUIREMENTS This section deals with the general requirements for a work environment free from exposure to electrical hazards. Protection of workers begins with careful planning and proper design. Safe work practices shall2.1 be used to safeguard employees from injury while they are exposed to electrical hazards. The training of personnel in safety-related work practices that pertain to their respective job assignments is discussed. 2.1 ELECTRICAL MAINTENANCE OR REPAIRS Only qualified persons, which include persons working under the direct supervision of a qualified person, shall2.2 perform electrical repairs. Before any electrical maintenance or troubleshooting is performed, sources of hazardous electrical energy shall2.3 be placed in an electrically-safe work condition except when it is necessary for troubleshooting, testing, or areas that are infeasible.

2.1.1 Work on Electrical Equipment The first consideration for working on any electrical system operating at 50 volts (V) or higher is to place the circuit in an electrically-safe work condition, which is defined in Appendix B. Work on energized circuits of 50 V or higher is not considered a routine activity. All circuits and equipment shall2.4 be considered energized until opened, tagged, and/or locked according to an approved procedure, and proven de-energized with an approved electrical test instrument known to be in proper working order. After de-energizing and where possible, the circuit should be challenged in some way (e.g. pressing the start button) to prove hazardous energy has been removed. A review of system drawings and/or system walk downs should be performed to identify all potential sources of electrical energy within the scope of planned work activity. Where the possibility exists that the circuit can become energized from other sources, or where capacitive devices (including cables) may retain or build up a charge, the circuit should be grounded and shorted. When equipment contains storage batteries, workers should be protected from the various hazards associated with those devices (See Section 7.5). Whenever work is to be performed on a de-energized system, the work plan shall2.5 also identify and provide for protection against any unplanned contact with exposed energized parts in the vicinity of the work. When electrical equipment contains sources of stored or mechanical hazardous energy (i.e. thermal, mechanical, pneumatic), these sources shall2.6 be blocked or otherwise relieved. 2.1.2 Considerations for Working on Energized Systems and Equipment Energized parts to which an employee might be exposed shall2.3 be put into an electrically-safe work condition before the employee works on, or near them, unless the employer can demonstrate that de-energizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations. If energized systems and equipment are not placed into an electrically-safe work condition, qualified and authorized employees performing such tasks as electrical repairs, modifications, demolition, servicing, troubleshooting, and testing on energized electrical systems, parts, and equipment, shall2.1 comply with the following: 1. Personnel shall2.7 not work on energized circuits unless they are qualified to do so, or they work under the direct supervision of a qualified person in an approved on-the-job training program. 4 DOE-HDBK-1092-2013 2. Sufficient protection in the form of insulated tools, arc-rated (AR) apparel, insulated protective equipment, or other personal protective equipment (PPE) shall2.8 be used as necessary while working on or near exposed energized parts. 3. Other work, independent of voltage, that presents a significant shock, arc flash, or arc blast hazard to employees shall2.9 be analyzed and appropriate controls provided. 2.1.3 Safety Watch Responsibilities and Qualifications Safety watch is an additional control that exceeds the regulatory requirements. The responsibilities and qualifications of personnel for sites that require the use of a safety watch should consider the following items: 1. Training in methods of release of victims from contact with electrical energy, cardiopulmonary resuscitation (CPR), and the use of automated external defibrillators (AED).

2. The possession of a thorough knowledge of location and operation of emergency- shutdown push buttons and power disconnects. 3. The possession of a thorough knowledge of the specific working procedures to be followed and the work to be done. 4. Specific safety watch responsibilities, including: monitoring the work area for unsafe conditions or work practices and taking necessary action to ensure abatement of the unsafe condition or work practices; de-energizing equipment and alerting emergency rescue personnel as conditions warrant; maintaining visual and audible contact with personnel performing the work; and the removal of injured personnel, if possible. The safety watch should have no other duties that preclude observing, rendering aid if necessary, and preventing unqualified persons from crossing the established safe approach boundaries. 2.2 BASIC SAFEGUARDS To protect employees from electrical hazards, standards and federal regulations limit the performance of electrical work to qualified and authorized personnel. Specifically, OSHA requires that only a qualified person (per OSHA definition), or someone working under the direct supervision of a qualified person, is permitted to perform any repair, installation, or testing of electrical equipment. See Section 2.7 and the definitions of "Qualified Employee" or "Qualified Person" in Appendix B. Following Integrated Safety Management System (ISMS) principles should improve the safety of the workplace: 1. Define Work Scope a. Ensure that work is adequately planned through an approved work control process; b. Plan and analyze for safety in each step of a project; c. Conduct a pre-job briefing; and d. Define response to changing scope or conditions. 5 DOE-HDBK-1092-2013 2. Identify the hazards a. Refer to system drawings and perform system walk downs with workers; b. Identify potential hazards; c. Maintain electrical equipment in accordance with the manufacturer’s instructions; and d. Post electrical hazard warning labels. 3. Establish controls a. Use properly rated test equipment and verify its condition and operation before and after use; b. Know and practice applicable emergency procedures; c. Become qualified in CPR and first aid and maintain current certifications; d. Inspect and wear appropriate PPE and apparel; and e. Control access to work area. 4. Perform the work safely a. Maintain good housekeeping and cleanliness; b. Anticipate problems; c. Resist pressure to "hurry up"; and d. Maintain a questioning attitude. 5. Feedback a. Document work; and b. Conduct a post job briefing. 2.3 RESPONSIBILITIES Management is responsible to provide a workplace that is free from recognized hazards that might cause injury, illness, or death and to comply with the specific safety and health standards issued by federal, state, and local authorities. Managers expect their employees to comply with these regulations as well as the DOE requirements formulated for the health and safety of employees. Prevention of injury and illness requires the efforts of all and is a goal well worth achieving. 2.3.1 Management Responsibilities To ensure safety and protection of employees, managers have the following responsibilities: 1. Ensure that employees are provided a workplace that is free from recognized hazards; 2. Ensure that employees performing electrical work are trained and qualified (see Section 2.7);

3. Ensure that approved PPE and clothing is provided, available, and used properly; and 4. Establish, implement, and maintain procedures and practices that ensure safe conduct of electrical work. 6 DOE-HDBK-1092-2013 2.3.2 Employee Responsibilities Employees are responsible to comply with occupational safety and health regulations and standards that apply to their own actions and conduct, including immediately reporting to management unsafe and unhealthful conditions. See Section 8.1 for additional responsibilities of employees working on or around electrical equipment or systems operating above 600 volts. 2.4 MODIFICATIONS TO FACILITIES Modifications to existing and new facilities should be subject to inspection by the AHJ, or authorized designee, to verify compliance with the codes and standards in effect on the date that the work was approved by a final design review. If the installation involves a hazard to life, equipment, or property, current standards and codes should be used to mitigate the hazard. 2.5 APPROVAL OF ELECTRICAL EQUIPMENT Generally, consensus codes and standards do not obligate the user to retrofit existing installations to more current editions of the document. However, according to OSHA, there are installation requirements in 29 CFR 1910.303-308 that require compliance based on the date of original installations. In some cases, compliance is required regardless of installation date. Whenever a modification invalidates the original approval by the AHJ, the modification should meet the most current code or standard. An inspection should validate compliance. Generally, minor equipment modifications should not warrant complete update to current codes and standards unless the AHJ determines the lack of conformity to current codes and standards presents an imminent danger. All electrical equipment, components, and conductors shall2.10 be approved for their intended use, which means they are acceptable to the AHJ. There are several methods for determining acceptability to the AHJ, including: listing by a nationally recognized testing laboratory (NRTL), field evaluations by an NRTL or an inspection and approval by the AHJ or designee. Electrical utility generation, transmission and distribution equipment built to nationally recognized standards is considered acceptable. 2.6 CODES, STANDARDS, AND REGULATIONS Electrical or electronic equipment and work performed on these installations, shall2.11 comply with 10 CFR 851, DOE orders, state and local requirements (where applicable), and, where applicable, other relevant standards, regulations, codes, etc. from organizations, such as: 1. Institute of Electrical and Electronics Engineers (IEEE) 2. International Society of Automation (ISA) 3. National Electrical Manufacturers Association (NEMA) 4. American National Standards Institute (ANSI) 5. American Society for Testing and Materials (ASTM) 6. National Fire Protection Association (NFPA) 7. NRTL’s recognized by OSHA, such as: a. Underwriters Laboratory, Inc. (UL) 7 http:shall2.11 http:shall2.10 DOE-HDBK-1092-2013 b. Factory Mutual Research Corporation (FMRC) 8. National Electrical Installation Standards (NEIS) When no clear applicable code or standard provides adequate guidance or when questions regarding workmanship, judgment, or conflicting criteria arise, personnel safety protection shall2.12 be the primary consideration. Therefore, when there are differing controls for similar hazards identified in the mandatory requirements of the relevant codes, standards, and regulations, the requirements that address the particular hazard and provides for the greatest margin of safety should govern.

2.7 TRAINING AND QUALIFICATIONS OF QUALIFIED WORKERS Only qualified workers or those working under the direct supervision of a qualified person in an on-the-job training program shall2.2 perform work on electrical systems. There shall2.13 be an employee training program implemented to qualify workers in the safety-related work practices that pertain to their respective job assignments. 2.7.1 Formal Training and Qualifications According to 10 CFR 851 which references such standards as NFPA 70E, 110.6(D), the employer is obligated to provide training and qualifications for qualified workers before they are permitted to perform electrical work. Refresher training is recommended at intervals, not to exceed three years, to provide an update on new regulations and electrical safety criteria. The training shall2.14 include on-the-job and/or instructor-led methods in a classroom setting. Portions of the training may be provided using self-paced methods such as self-study of print material, web-based training or computer-based training. The degree of training provided should be determined by the risk to the employee. This training shall2.15 be documented. Qualified employees shall2.16 be trained and familiar with, but not be limited to, the following: 1. Safety-related work practices, including hazard identification and analysis, and proper selection, use and care of PPE, that pertain to their respective job assignments. 2. Skills and techniques necessary to distinguish exposed energized parts from other parts of electrical equipment. 3. Skills and techniques necessary to determine the nominal voltage of exposed energized parts, clearance distances, and the corresponding voltages to which the qualified person might be exposed. 4. Procedures on how to perform their jobs safely and properly. 5. How to lockout/tagout energized electrical circuits and equipment safely. 6. Approach distances defined in NFPA 70E. 7. Knowledge to select and use adequately rated test instruments. Other types of training to be considered for electrical workers should include the following: 1. National Electrical Code (NFPA 70); 2. National Electrical Safety Code (IEEE/ANSI C2); 3. Standard for Electrical Safety in the Workplace (NFPA 70E); 4. Use of personal protective grounds; 8 http:shall2.16 http:shall2.15 http:shall2.14 http:shall2.13 http:shall2.12 DOE-HDBK-1092-2013 5. Work permit and work authorization procedures; 6. Proper clothing required for arc flash or arc blast protection; and 7. First-aid, CPR, AED, and methods of release training. OSHA under 29 CFR 1910.269(a), Electric Power Generation, Transmission, and Distribution, and 1910.332, Electrical Training, also require training for persons other than qualified workers if their job assignments bring them within a safe distance of hazardous electrical energy. Supervisors of unqualified personnel should have at least the same level of electrical safety training if the work of those they supervise bring them close enough to exposed parts of electrical circuits for a hazard to exist. 2.7.2 Training of Safety Personnel Safety personnel designated to support electrical safety programs should be knowledgeable and trained at levels commensurate with their duties. Supervisors directly supervising energized work should have at least the same level of electrical safety training as the workers they supervise. 2.7.3 Training of Technical Personnel

In addition to electrical safety training requirements, DOE Order 426.2 provides criteria for technical personnel supporting an operating nuclear facility. According to the order, not only do affected personnel require basic qualification training, but their qualification is to be recertified every two years. 2.8 WORKING SPACE AROUND ELECTRICAL EQUIPMENT Working space around electrical enclosures or equipment shall2.17 be adequate for conducting all anticipated maintenance and operations safely, including sufficient space to ensure safety of personnel working during emergency conditions and workers rescuing injured personnel. Spacing shall2.18 provide the dimensional clearance (addressed in the following subsections) for personnel access to equipment likely to require examination, adjustment, servicing, or maintenance while energized. Such equipment includes panelboards, switches, circuit breakers, switchgear, controllers, and controls on heating and air conditioning equipment. These clearances should be in accordance with the most restrictive of OSHA, NESC, or NEC requirements. These working clearances are not required if the equipment is not likely to require examination, adjustment, servicing, or maintenance while energized. However, sufficient access and working space is still required. Sufficient working space is necessary for the protection of workers to ensure there is adequate space for safe egress and entry into areas where energized work is likely. Dedicated space, which includes the area directly above electrical equipment, is necessary for the protection of electrical equipment and to allow for safe future expansion. See OSHA and NFPA 70 (NEC) for more information on clearing space and dedicated space. 2.8.1 Electrical Equipment Rated at 600 Volts or Less A minimum working space 30 inches wide shall2.18 be provided in front of electrical equipment rated at 600 V or less and is likely to require servicing while energized. This provides room to 9 http:shall2.18 http:shall2.18 http:shall2.17 DOE-HDBK-1092-2013 avoid body contact with grounded parts while working with energized components of the equipment. The 30-inch wide space may be centered in front of the equipment or can be offset. The depth of the working space shall2.19 be clear to the floor. Where rear access is required to work on de-energized parts, a minimum of 30 inches shall2.20 be provided. There shall2.21 be clearance in the work area to allow at least a 90-degree opening of equipment doors or hinged panels on the service equipment. Working spaces may overlap. The depth of the working space shall2.18 be 3 feet, 3.5 feet, or 4 feet, depending upon existing conditions. The conditions are as follows: 1. Condition 1: Exposed live parts on one side of the working space and no live or grounded parts on the other side of the working space, or exposed live parts on both sides of the working space that are effectively guarded by insulating materials. 2. Condition 2: Exposed live parts on one side of the working space and grounded parts on the other side of the working space. Concrete, brick, or tile walls shall2.22 be considered as grounded. 3. Condition 3: Exposed live parts on both sides of the working space. See Fig. 2-1 for the clearance requirements in front of electrical equipment rated 600 V or less. Fig. 2-1. Minimum clearances in front of electrical equipment (600 V or less). 10 http:shall2.22 http:shall2.18 http:shall2.21 http:shall2.20 http:shall2.19

DOE-HDBK-1092-2013 2.8.2 Electrical Equipment Rated over 600 Volts OSHA and the NEC lists minimum clearances required for working spaces in front of high- voltage electrical equipment such as switchboards, control panels, switches, circuit breakers, switchgear, and motor controllers. There are three conditions to apply: 1. Exposed live parts on one side of the working space and no live or grounded parts on the other side of the working space, or exposed live parts on both sides of the working space that are effectively guarded by insulating materials. 2. Exposed live parts on one side of the working space and grounded parts on the other side of the working space. Concrete, brick, or tile walls shall2.23 be considered as grounded. 3. Exposed live parts on both sides of the working space. See Fig. 2-2 for the clearance requirements in front of electrical equipment rated at over 600 V. Fig. 2-2. Minimum clearances in front of electrical equipment (over 600 V). 11 http:shall2.23 DOE-HDBK-1092-2013 2.9 IDENTIFICATION OF DISCONNECTING MEANS Disconnecting means in service panels, subpanels, or elsewhere shall2.24 be marked to show what loads or equipment are supplied, unless located and arranged so that the purpose is evident. 2.9.1 Disconnecting Means Disconnecting means (e.g., a disconnect switch or circuit breaker) shall2.25 be located for easy access and shall2.24 be clearly and permanently marked to show the purpose of the disconnecting means, unless located and arranged so that the purpose is evident. Labeling should match and be traceable to appropriate drawings. This applies to all existing electrical systems and all new, modernized, expanded, or altered electrical systems. Disconnecting means shall2.26 be capable of being locked out where required. 2.9.2 Panelboard Circuit Directories Panelboard circuit directories shall2.24 be provided and maintained accurate. 2.9.3 Enclosure Labeling Printed labeling or embossed identification plates affixed to enclosures shall2.24 comply with the requirements that disconnects are legibly marked and that the marking shall2.24 be of sufficient durability for the environment involved. 2.9.4 Load Labeling As with the disconnecting device, the load should be labeled. For example, the motor, the controller, and the disconnecting device could have the same identification number. 2.9.5 Source Labeling The source supplying power to the disconnecting means and load should be labeled as well. This good practice allows the electrical worker to know the identification of the elements from the source of power through the entire circuit. (See Fig. 2-3.) 12 http:shall2.24 http:shall2.24 http:shall2.24 http:shall2.26 http:shall2.24 http:shall2.25 http:shall2.24 DOE-HDBK-1092-2013 Fig. 2-3. Marking of disconnecting means. 2.10 WORK INSTRUCTIONS Before electrical work begins, the qualified worker should review and understand the work instructions to ensure the work can be performed safely and compliantly. 2.10.1 Safe Work Instructions and Supervision Electrical work should be performed according to safety procedures. Energized electrical work should be directed by a supervisor who is qualified by training and experience in the applicable safety-related work practices. Workers should report any electrical hazards to their immediate supervisor. The supervisor should take all corrective actions necessary to address an employee's concerns.

Electrical instructions shall2.27 be based on a thorough analysis of the job and its hazards. If the same task is repeated, it may be performed under specific work rules that are based on such analyses. 2.10.2 Work Planning Electrical work planning may include, but not be limited to, the following: 1. Hazardous Energy Control (Lock Out/Tag Out) 2. Shock Hazard Analysis 3. Flash Hazard Analysis 13 http:shall2.27 DOE-HDBK-1092-2013 4. Safe work practices necessary to prevent exposure of the workers to electrical hazards 5. Methods of using test equipment to ensure safe conditions 6. Provision that insulated protective equipment is rated for the highest voltage present 7. Qualification requirements of personnel (see Section 2.7) 8. PPE and protective clothing (e.g., hardhats, safety shoes, eye and face protection, insulated live-line tools/barriers, hot sticks, AR clothing, and arc flash protection, etc.) 9. Special provisions for working on experimental equipment 10. The need to conduct a pre-job safety briefing 11. Temporary protective grounding equipment 12. Temporary lighting 13. Consideration for "what can go wrong" 14. Incorporating lessons learned from similar work tasks 15. Worker feedback in the planning process 2.11 ELECTRICAL PERSONAL PROTECTIVE EQUIPMENT Qualified workers are responsible for avoiding and preventing accidents while performing electrical work, repairs, or troubleshooting electrical equipment. Personnel shall2.28 wear PPE and protective clothing that is appropriate for safe performance of work. Personnel shall2.29 wear appropriate AR clothing and PPE whenever there is potential exposure to an electrical arc flash. Required AR clothing shall2.30 meet the requirements of ASTM F 1506, Standard Performance Specifications for Flame Retardant Textile Materials for Wearing Apparel for Use by Electric Workers Exposed to Momentary Electric Arc and Related Thermal Hazards. 2.11.1 Management's Responsibilities Managers shall2.31 ensure that appropriate PPE is provided, used, and that employees using PPE are trained in the proper use of the PPE. 2.11.2 Inspecting PPE Employees shall2.32 visually inspect PPE and protective clothing prior to use, as well as after any work performed that could have damaged the PPE or apparel. Such inspections shall2.32 include a field air test of the gloves used. Visual inspection shall2.33 be performed on hot sticks, grounds, aerial lift equipment and booms, rope, ladders, insulated tools, AR clothing, etc. Equipment that does not successfully pass visual inspection shall2.34 not be used and shall2.34 be returned for repair and testing or disposal. 2.11.3 Cleaning and Electrical Testing of PPE Rubber-insulated PPE issued for use shall2.34 receive periodic cleaning and electrical testing in accordance with the requirements of 29 CFR 1910.137 and the appropriate ANSI/ASTM standards. The intervals of retest for rubber goods issued for service shall2.35 not be more than 6 months for gloves, and 12 months for sleeves and blankets. Gloves or sleeves that have been electrically tested, but not issued for service, shall2.35 not be placed into service unless they have been electrically tested within the previous 12 months. A record of testing of PPE should be maintained according to applicable standards. 14 http:shall2.35 http:shall2.35 http:shall2.34 http:shall2.34 http:shall2.34 http:shall2.33 http:shall2.32 http:shall2.32 http:shall2.31 http:shall2.30 http:shall2.29 http:shall2.28

DOE-HDBK-1092-2013 AR apparel that becomes contaminated with grease, oil, or flammable liquids or combustible materials should not be used. The garment manufacturer’s instructions for care and maintenance should be followed. When AR clothing is cleaned, manufacturer’s instructions should be followed to avoid loss of protection. When AR clothing is repaired, the same AR materials used to manufacture the AR clothing should be used to repair the garment. 2.11.3.1 Testing All testing methods, apparatus, and facilities shall2.34 meet the applicable ANSI/ASTM standards. The method used and the results of such tests should be documented and made available for inspection. 2.11.3.2 Retested PPE Retested rubber-insulated PPE shall2.34 be identified to indicate the date of the latest test, or date of retest, in accordance with the appropriate standard cited in 29 CFR 1910.137, Standards on Electrical Protective Equipment. Manufacturer's recommendations shall2.34 be followed on the type of paint or ink to be used. 2.11.4 Live-Line Tools Live-line tools shall2.36 be cleaned and inspected before use and receive a dielectric test whenever their insulating value is suspect. A record of the testing of live-line tools shall2.37 be maintained. 2.11.5 Fiberglass-Handled Tools Fiberglass-handled tools shall2.38 be designed and constructed by the manufacturer to withstand 100 kV per foot of length. The in-service test shall2.39 be 75 kV per foot. 2.11.6 Maximum-Use Alternating Current (AC) Voltage Maximum-Use AC voltage phase-to-phase or phase-to-ground for insulating blankets, mats, covers, line hose, sleeves, and gloves, as shown in Table 2-1 shall2.34 be as follows: Class Voltage Label Color 00 500 Beige 0 1,000 Red 1 7,500 White 2 17,500 Yellow 3 26,500 Green 4 36,000 Orange Table 2-1. Class and rating of rubber insulating PPE. 2.11.7 Maximum Usage Voltage for Live-Line Tools Maximum usage voltage per foot of length and phase-to-phase or phase-to-ground for live-line tools shall2.40 be as follows: 1. Tools with wooden handles: 75 kV 15 http:shall2.40 http:shall2.34 http:shall2.39 http:shall2.38 http:shall2.37 http:shall2.36 http:shall2.34 http:shall2.34 http:shall2.34 DOE-HDBK-1092-2013 2. Tools with fiberglass handles: 100 kV 2.11.8 Rubber-Insulated Gloves Whenever rubber-insulated protective gloves are required for shock protection, approved protective gloves shall2.41 also be worn. In some cases, rubber-insulated protective gloves may be used without protectors, see 29 CFR 1910.137 and referenced standards for those conditions. 2.11.9 Storage Electrical insulating and protective clothing and equipment should be stored lying flat, undistorted, right-side out, and unfolded, as appropriate, in protective containers. Blankets may be stored rolled provided the inner diameter of the roll is at least 2 inches. Rubber goods shall2.42 be stored in a location that is as cool, dark, and dry as possible. The location should be as free as practicable, from ozone, chemicals, oils, solvents, damaging vapors and fumes, and away from electrical discharges and sunlight. Rubber gloves should be stored cuff-down in a bag, box, or container designed for rubber glove storage. Rubber gloves may be kept inside of leather protectors. 2.11.10 Safety Shoes, Hardhats, and Glasses

Safety shoes (ASTM F 2413, Standard Specification for Performance Requirements for Protective (Safety) Toe Cap Footwear, and F 2412, Standard Test Methods for Foot Protection), hardhats (ANSI/ISEA Z89.1, American National Standard for Industrial Head Protection), and safety glasses (ANSI/ASEE Z87.1, Occupational and Educational Personal Eye and Face Protection Devices) and face shields (ASTM F 2178, Standard Test Method for Determining the ARC Rating and Standard Specification for Face Protective Products) worn by electrical workers shall2.43 meet the requirements of appropriate standards. 2.12 WORK PRACTICES NFPA 70E, OSHA regulations, and the NESC cover electrical safety-related work practices and procedures for qualified and unqualified employees exposed to energized electrical conductors or circuit parts in workplaces. This information provides a foundation for establishing an electrically-safe working environment. Basic work strategies include: 1. Establishing an electrically-safe work condition; 2. Training (see Section 2.7); 3. Planning the work; 4. Identifying required personal protective equipment; and 5. Utilizing Energized Electrical Work Permits, when required. 2.12.1 Establishing an Electrically-Safe Work Condition As referenced in 10 CFR 851, NFPA 70E, 120.1 provides a six-step process for achieving an Electrically-Safe Work Condition. For transmission and distribution work in excess of 600 V see 29 CFR 1910.269. 16 http:shall2.43 http:shall2.42 http:shall2.41 DOE-HDBK-1092-2013 2.12.1.1 Exposed Energized Parts Energized parts to which an employee may be exposed shall2.3 be de-energized before the employee works on, or near, them, unless it can be demonstrated and documented that de­ energizing introduces additional or increased hazards or is infeasible because of equipment design or operational limitations (see Section2.1.2). 2.12.1.2 Safe Procedure Safe procedures for de-energizing circuits and equipment shall2.44 be determined before circuits or equipment are de-energized. De-energization procedures shall2.45 be included in the lockout/tagout procedure for the circuit or equipment to be de-energized. 2.12.1.3 Circuits and Equipment Circuits and equipment to be worked on shall2.45 be disconnected from all electric energy sources. Control circuit devices such as push-buttons, selector switches, and interlocks shall2.45 not be used as the sole means for isolating circuits or equipment. 2.12.1.4 Stored Electrical Energy Stored electrical energy that might endanger personnel shall2.46 be placed in a safe state. Capacitors shall2.46 be discharged and high-capacitance elements shall2.46 be short-circuited and grounded if the stored electrical energy could endanger personnel. 2.12.1.5 Stored Non-Electrical Energy Stored non-electrical energy in devices that could re-energize electric circuit parts shall2.47 be blocked or relieved to the extent that the device could not accidentally energize the circuit parts. Examples include wound springs and pneumatic-driven devices. Fig. 2-5. A lockout/tagout program is required. 2.12.1.6 Lockout/Tagout Procedure Each employer shall2.48 document and implement lockout/tagout procedures to safeguard employees from injury while they are working on or near de-energized electric circuits and equipment. The lockout/tagout procedures shall2.49 meet the requirements of 29 CFR 1910.147(c) to (f), The Control of Hazardous Energy (lockout/tagout), 1910.269(d) and (m), 1910.333, Selection and Use of Work Practices, 1926.417, Lockout and Tagging of Circuits,

17 http:shall2.49 http:shall2.48 http:shall2.47 http:shall2.46 http:shall2.46 http:shall2.46 http:shall2.45 http:shall2.45 http:shall2.45 http:shall2.44 DOE-HDBK-1092-2013 DOE-STD-1030-96, Guide to Good Practice for Lockouts and Tagouts, and NFPA 70E, as applicable (see Fig. 2-5). 2.12.1.7 Verification of De-energized Condition Verification shall2.50 be made to ensure that all circuits, parts, and other sources of electrical energy, including mechanical energy, have been disconnected, released, or restrained. All electrical circuit conductors and circuit parts shall2.4 be considered energized until the source of energy is removed and verified. A qualified worker shall2.51 operate the equipment operating controls, perform voltage verification, and inspect open switches and draw out breakers to ensure that energy sources are isolated. 2.12.1.8 Voltage Verification Test A qualified worker shall2.50 use appropriate test equipment to test the circuit elements and electrical parts of equipment to which employees will be exposed and shall2.50 verify that the circuit elements and equipment parts are de-energized. The test shall2.50 also determine if a hazardous energized condition exists as a result of induced voltage or voltage backfeed after specific parts of the circuit have been de-energized. The test equipment shall2.52 be checked for proper operation immediately before and immediately after this test. Testing shall2.53 be performed as if the circuit is energized, wearing the appropriate PPE. The voltage verification device used shall2.52 be rated for the application. Proximity testers and solenoid-type devices shall2.52 not be used to test for the absence of voltage for purposes of establishing lockout/tagout. Use of low-impedance test instruments should be considered when there is the possibility of small induced voltages to detect when those voltages would be hazardous. 2.12.1.9 Application of Personnel Protective Grounds Personnel protective grounds shall2.54 be applied on circuits where residual charges may accumulate. Personnel protective grounds shall2.54 be selected and installed in accordance with appropriate standards (see Sections 8.5 and 13.5.1.2.2). Consideration should be given to step and touch potentials in the area of the temporary ground connections. 2.12.1.10 Re-energizing Equipment The requirements in the following subsections shall2.55 be met before circuits or equipment are re- energized, even on a temporary basis: 2.12.1.10.1 Tests and Visual Inspections A qualified worker shall2.56 verify that all personnel are in the clear and that all tools, electrical jumpers, shorts, grounds, and other such devices have been removed, so that the circuits and equipment can be safely energized. 2.12.1.10.2 Warning Employees Employees exposed to the hazards associated with re-energizing the circuit or equipment shall2.57 be warned to stay clear of circuits and equipment. 18 http:shall2.57 http:shall2.56 http:shall2.55 http:2.12.1.10 http:shall2.54 http:shall2.54 http:shall2.52 http:shall2.52 http:shall2.53 http:shall2.52 http:shall2.50 http:shall2.50 http:shall2.50 http:shall2.51 http:shall2.50 DOE-HDBK-1092-2013 2.12.1.10.3 Removing Lock and Tag Each lock and tag shall2.58 be removed by applying the following: 1. Each lockout or tagout device shall2.58 be removed from each energy-isolating device by the authorized employee who applied the lockout or tagout device, or under his/her direct supervision, or as stated below.

2. When the authorized employee who applied the lockout or tagout device is not available to remove it, that device may be removed under the direction of his or her supervisor. Specific procedures shall2.59 be followed, including, at a minimum, the following elements: a. Verification by the supervisor that the authorized employee who applied the device is not at the affected facility. b. Making all reasonable efforts to contact the authorized employee to inform him or her that the lockout or tagout device has been removed. c. Ensuring that the authorized employee has this knowledge before he or she resumes work at the affected facility. 2.12.2 Training Qualified workers shall2.60 be knowledgeable of, and trained in, safety-related work practices, safety procedures, and other requirements that pertain to their respective job assignments. Employees shall2.61 not be permitted to work in an area where they are likely to encounter an electrical hazard, unless they have been trained to recognize and avoid these hazards. (See Section 2.7.) 2.12.3 Planning the Work Whenever electrical equipment is taken from its accepted and static condition, an appropriate level of hazard analysis and work planning shall2.62 be completed before a worker is dispatched to manipulate the equipment. The analysis and associated work instructions shall2.62 account for any electrical hazards that result from the assigned task. Hazard controls shall2.63 be selected based on the following hierarchy: 1. Elimination or substitution of the hazards where feasible and appropriate. 2. Engineering controls where feasible and appropriate. 3. Work practices and administrative controls that limit worker exposures. 4. Personal protective equipment. 2.12.3.1 Safe Work Instructions and Supervision Before electrical work begins, the qualified worker should review and understand the work instructions to ensure the work can be performed safely and compliantly. Electrical work should be performed according to safety procedures. A supervisor who is qualified by training and experienced in the applicable safety-related work practices should direct energized electrical work. Workers should report any electrical hazards to their immediate supervisor. The supervisor should take all corrective actions necessary to address an employee's concerns. 19 http:shall2.63 http:shall2.62 http:shall2.62 http:shall2.61 http:shall2.60 http:shall2.59 http:shall2.58 http:shall2.58 DOE-HDBK-1092-2013 Electrical instructions shall2.64 be based on a thorough analysis of the job and its hazards. If the same task is repeated, it may be performed under specific work rules that are based on such analyses. 2.12.3.2 Hazard Analysis and Control Electrical hazard analysis and control considerations may include, but not be limited to, the following: 1. Hazardous Energy Control (Lock Out/Tag Out); 2. Shock Hazard Analysis; 3. Flash Hazard Analysis; 4. Safe work practices necessary to prevent exposure of the workers to electrical hazards; 5. Methods of using test equipment to ensure safe conditions; 6. Provision that insulated protective equipment is rated for the highest voltage present; 7. Qualification requirements of personnel (see Section 2.7); 8. PPE and protective clothing (e.g., hardhats, safety shoes, eye and face protection, insulated live-line tools/barriers, hot sticks, AR clothing, and arc flash protection, etc.);

9. Special provisions for working on experimental equipment; 10. The need to conduct a pre-job safety briefing; 11. Temporary protective grounding equipment; 12. Temporary lighting; 13. Consideration for "what can go wrong"; 14. Incorporating lessons learned from similar work tasks; and 15. Worker feedback in the planning process. 2.12.3.3 Safe Energized Work (Hot Work) If live parts are not placed into an electrically-safe work condition, work to be performed shall2.65 be considered energized electrical work and shall2.65 be performed by written permit only. Work performed on energized conductors by qualified persons related to tasks such as testing, trouble-shooting, voltage measuring, etc., shall2.66 be permitted to be performed without an energized electrical work permit, provided appropriate safe work practices and PPE are provided and used. Safety-related work practices shall2.27 be used to prevent electrical shock or other electrically induced injuries when employees work on, or near, electrical conductors or circuit parts that are energized. Only qualified workers who are knowledgeable and have been trained to work safely on energized circuits and trained to use the appropriate PPE, protective clothing, insulating shielding materials, insulated tools shall2.67 be permitted to work on energized conductors or circuit parts and have an authorized energized work permit (refer to NFPA 70E, Article 130.1). 20 http:shall2.67 http:shall2.27 http:shall2.66 http:shall2.65 http:shall2.65 http:shall2.64 DOE-HDBK-1092-2013 2.12.3.4 Approach Distance No unqualified employee shall2.60 be permitted to approach closer to exposed, energized lines or parts than the Restricted Approach Boundary. The unqualified worker shall2.60 be permitted to cross the Limited Approach Boundary only when continuously escorted by a qualified worker. No worker shall2.68 approach or take any conductive object, including jewelry, nearer to exposed live parts than the Restricted Approach Boundary. 2.12.3.5 Multiple Workers Due to the potential for exposure to energized parts, electrical work that presents a shock or arc flash hazard to employees should be analyzed to determine the necessary number of employees involved. 2.12.3.6 Illumination and Egress Routes Adequate illumination shall2.69 be provided and emergency routes should be identified before workers are allowed to enter spaces containing exposed energized parts. 2.12.3.7 Systems Under Load Electrical equipment intended to switch current should have a rating sufficient for the current. Manual switches and disconnects, taps, terminators, and non-enclosed switches should not be operated while under load, unless the devices are rated as load-break type and are so marked. 2.12.3.8 Working with Test Instruments and Equipment

Sometimes it becomes necessary to check the continuity of power circuits, control circuits, etc., by using a particular testing instrument (volt, ohm, and/or amp meter) designed for the testing involved. The voltage device used shall2.70 be rated for the application. Proximity testers and solenoid-type devices shall2.70 not be used to test for the absence of voltage, except for applications above the service point, because they do not accurately detect and/or measure voltage. Also, proximity testers do not detect direct current (DC) or AC voltage in a cable that is shielded. Proximity testers are very useful in certain applications, (for example, for finding cables that go through a panel, but that do not terminate in the panel, or for testing energized electrical equipment ahead of the service point). However, it should be noted that a proximity tester’s failure to detect voltage does not guarantee that the equipment or device is de­ energized. The absence of voltage shall2.70 only be verified with a voltmeter rated for the application. When appropriate, test instruments and associated leads, probes, etc. should meet the American National Standard for voltmeters, ANSI/ISA/UL-61010-1, Safety Requirements for Electrical Equipment for Measurement, Control, and Laboratory Use. Appropriate category rated and listed meters should be used. 2.12.3.8.1 Qualified Employees Only qualified workers who have been trained to work safely with test instruments and equipment on energized circuits shall2.50 be permitted to perform testing work on electrical circuits or equipment where there is danger of injury from accidental contact with energized parts or improper use of the test instruments and equipment. 2.12.3.8.2 Visual Inspections Test instruments and equipment and all associated test leads, cables, power cords, probes, and connectors shall2.71 be visually inspected for external defects or damage before being used. If 21 http:shall2.71 http:shall2.50 http:shall2.70 http:shall2.70 http:shall2.70 http:shall2.69 http:shall2.68 http:shall2.60 http:shall2.60 DOE-HDBK-1092-2013 there are defects or evidence of damage that might expose an employee to injury, the defective or damaged item shall2.71 not be used until replaced and tests have been made. 2.12.3.8.3 Rating Instruments and American National Standards Institute Equipment Test instruments and equipment and their accessories shall2.72 be rated for the circuits and equipment to which they will be connected and shall2.73 be suitable for the environment in which they will be used. 2.12.3.8.4 Calibration of Electrical Instruments ANSI Standard C39.1, Requirements for Electric Analog Indicating Instruments, defines the minimum performance and general requirements level for electrical instruments. ANSI standards also ensure that an instrument, when calibrated to National Institute of Standards and Technology traceable standards, is capable of transferring that quality of measurement to field conditions, within specified limits, when that level of measurement quality is needed. A record should be maintained for each instrument, by serial number or equivalent method that shows: the dates of inspection; calibration data, as received; the date when it should be recalled from the field; and, a recalibration check made, and any interim repairs. 2.12.3.9 Work Near Overhead Lines

The work planning practices listed below should be used for: all work conducted near the limited approach boundary of electrical overhead lines; work inside underground electrical vaults; or, movement of any mechanical equipment near overhead lines. Work practices by qualified workers performed on electrical overhead lines should be applied using information contained in Section 8.0. 1. Work areas should be walked down by planners and workers to identify all electrical hazards during work planning. 2. Facility electrical maintenance or engineering organization, along with site electrical utilities should be involved in planning work in the vicinity of overhead electrical lines. 3. If it is possible to de-energize electrical overhead lines without causing a hazard greater than working near these lines, they should be de-energized prior to performing work. 4. Work performed near energized electrical lines should be controlled using a 2-barrier system, as described in item 6 below. 5. For work performed under high-voltage power lines (1 kV and higher), workers should be advised of potential static shock hazards, where a static charge may build up on conductive and non-conductive equipment and personnel (such as telephone wire, fences, and personnel who are working in an insulated bucket, ladder, or elevated platform). 6. All work near the limited approach boundary of overhead transmission and distribution lines, other than by electrical utility personnel, shall2.74 be performed in accordance with OSHA requirements. Two barriers should be incorporated to ensure no contact is made with energized overhead lines. Typical barriers include, but are not limited to: a. The use of trained spotters that have direct communication with the operator. b. Having electrical utility personnel measure line height to enable the spotter to accurately determine clearance distance. 22 http:shall2.74 http:shall2.73 http:shall2.72 http:shall2.71 DOE-HDBK-1092-2013 c. The installation of physical barriers to prevent encroachment into the limited approach boundary. d. The use of stakes or painted lines to provide constant reminders to operator and spotters of the proximity to overhead energized lines. e. The use of reflective materials to enhance visibility of overhead lines by spotters. f. The posting of signs indicating line height and clearance distance on common haul routes to warn of overhead energized electrical lines and enable the spotter to accurately determine clearance distance. g. Having electrical utility personnel rise or relocate overhead power lines to reduce possibility of inadvertent contact. h. The use of other control(s) that may be available and permitted provided they are effective. 2.12.4 Personal Protective Equipment PPE is a last barrier for protecting the worker from hazards associated with the use or maintenance of electrical equipment and systems. It is a means for isolating the worker when establishing an electrically-safe work condition is not feasible or creates a greater hazard. See Section 2.11 for specific information regarding electrical PPE use and care. PPE for electrical shock hazard shall2.74 be selected based on the results of a Shock Hazard Analysis required by NFPA 70E, 130.2(A). Arc flash PPE shall2.74 be selected based on the results of a Flash Hazard Analysis required by NFPA 70E, 130.3. Electrical workers should wear non-melting clothing, safety glasses, and leather gloves as minimum protection whenever working on or around energized electrical equipment.

2.12.5 Electrical Injuries All electrical injuries (other than obvious static shocks) should be reported to supervision immediately. Electrical injuries may include thermal burns, arc burns, arc blast trauma, and electrical shocks. A medical professional should evaluate electrical injury victims as soon as possible. 23 http:shall2.74 http:shall2.74 DOE-HDBK-1092-2013 3.0 Hazard Analysis Paragraph 21 of 10 CFR 851, mandates "Contractors must establish procedures to identify existing and potential workplace hazards and assess the risk of associated worker injury and illness." Specific to electrical hazards, OSHA and NFPA 70E provide methods that electrical planners and workers use to develop processes to identify hazards in the workplace. Monthly performance metrics have shown that these methods appear to be effective since their implementation at DOE workplaces over the past several years. Recognizing that, in addition to standard industrial electrical hazards, many DOE workplaces have electrical hazards that may not be familiar to the general public or, in some cases; to all members of the organizations that develop consensus electrical codes and standards. Some DOE contractors have developed procedures that attempt to address these individual hazards and processes. Each site should incorporate a process based on the best interest of the site and workers. 24 DOE-HDBK-1092-2013 4.0 ELECTRICAL PREVENTIVE MAINTENANCE The term "electrical preventive maintenance" (EPM) refers to a program of regular inspection and service of equipment to detect potential problems and to take proper corrective measures. 4.1 DEVELOPMENT AND IMPLEMENTATION REQUIREMENTS An EPM program should be developed and implemented based on the requirements of: 1. DOE O 433.1, Maintenance Management Program for DOE Nuclear Facilities 2. NFPA 70B, Recommended Practice for Electrical Equipment Maintenance 3. NFPA 70E, Standard for Electrical Safety in the Workplace 4. NFPA 72, National Fire Alarm Code 5. ANSI/NETA MTS, National Electrical Testing Association, Standard for Maintenance Testing Specifications 6. IEEE/ANSI-C2, National Electrical Safety Code 4.2 ELECTRICAL PREVENTIVE MAINTENANCE PROGRAM An EPM program is defined as a managed program of inspecting, testing, analyzing, and servicing electrical systems and equipment with the purpose of maintaining safe operations and production by reducing or eliminating system interruptions and equipment breakdowns. This system manages the conduct of routine inspections and tests and the servicing of electrical equipment so that impending troubles can be detected and reduced or eliminated. When designers, installers, or constructors specify, install, and construct equipment with optional auxiliary equipment, that optional equipment should be part of the EPM program. Records of all inspections, tests, and servicing should be documented and reviewed. All electrical equipment that is appropriate for EPM should be inspected, tested, and serviced in accordance with an EPM program. Inspections, tests, and servicing shall4.1 be performed by personnel who are qualified for the work to be performed. These qualifications can be shown by appropriate documentation of work experience, on-the-job training, as well as offsite formal training to verify understanding and retention of minimum knowledge, skills, and abilities.

4.3 MAINTENANCE Electrical equipment should be maintained in accordance with the manufacturer's recommendations and instructions for the local operating environment. A copy of the manufacturer's recommendations should be documented and on file. 4.4 INSPECTION If an EPM program does not exist, an inspection, testing, and servicing program should be developed and implemented to establish a baseline to initiate an EPM program. The inspection frequency should be as recommended by the manufacturer or as otherwise indicated in NFPA 70B. An initial period of inspection (sometimes several years) provides sufficient knowledge 25 DOE-HDBK-1092-2013 that, when accumulated, may permit increasing or decreasing that interval, based upon documented observations and experience. 4.5 ESSENTIAL ELEMENTS The EPM program should include the essential elements described in NFPA 70B, Chapter 5, What is an Effective EPM Program? This includes planning, identifying the main parts, and utilizing available support services for a program. For example, an EPM program should include the following essential ingredients: 1. Responsible and qualified personnel; 2. A survey and an analysis of electrical equipment and systems to determine maintenance requirements and priorities; 3. Programmed routine inspections and suitable tests; 4. Accurate analysis of inspection and test reports so that proper corrective measures can be prescribed; 5. Performance of necessary work; and 6. Concise, but complete, records. 4.6 PLANNING AND DEVELOPING AN EPM PROGRAM, AND FUNDAMENTALS OF EPM The EPM program should be planned and developed to include each of the functions, requirements, and economic considerations described in NFPA 70B, Chapter 6, Planning and Developing an EPM Program, and NFPA 70B, Chapter 8, Fundamentals of EPM. Chapter 6 includes: surveying the existing electrical system installation; identifying crucial equipment; establishing a systematic program to follow; and, developing methods and procedures to plan, analyze, and record maintenance activities. Electrical drawings should be kept current. A system of recording changes in electrical systems and then integrating those changes into the applicable drawings should be developed and implemented. NFPA 70B includes designing to accommodate maintenance, scheduling maintenance, personnel and equipment safety, circuit protection, and initial acceptance testing. 4.7 GROUND FAULT PROTECTION AND ARC FAULT CIRCUIT INTERRUPTERS The EPM program should include the essential ingredients of Chapter 15 of NFPA 70B, Ground Fault Protection. This includes ground fault circuit interrupters (GFCls) and ground fault protection for equipment (GFPE). Ground fault protective devices are intended to protect personnel and equipment. There are two distinct types: the GFCI and the GFPE. It is extremely important to understand the difference between them. A Class A GFCI trips when the current to ground has a value in the range of 4 through 6 milliamperes (mA) and is used for personnel protection. A Class B GFCI (commonly used as ground fault protection for equipment) trips when the current to ground exceeds 20 mA. A Class B GFCI is not suitable for employee protection. 26 DOE-HDBK-1092-2013 A GFCI is defined in Article 100 of the NEC as a device intended for the protection of personnel that functions to de-energize a circuit, or portion thereof, within an established period of time, when a current to ground exceeds a set value.

4.7.1 Ground Fault Circuit Interrupters (GFCIs) Ground fault circuit protection should be permitted to be used in any location, circuit, or occupancy to provide additional protection from line-to-ground shock hazards because of the use of electric hand tools. Where GFCI protection is not permanently installed, portable GFCI protection is acceptable. 4.7.1.1 How a GFCI Works GFCIs are devices that sense when current—even a small amount—passes to ground through any path other than the proper conductor. When this condition exists, the GFCI quickly opens the circuit, stopping all current flow to the circuit and to a person receiving the ground fault. Figure 4-1 shows a typical circuit arrangement of a GFCI designed to protect personnel. The incoming two-wire circuit is connected to a two-pole, shunt-trip overload circuit breaker. Fig. 4-1. Principle of GFCI operation. 27 DOE-HDBK-1092-2013 The load-side conductors pass through a differential coil onto the outgoing circuit. As long as the current in both load wires is within specified tolerances, the circuit functions normally. If one of the conductors comes in contact with a grounded condition or passes through a person's body to ground, an unbalanced current is established. The differential transformer picks up this unbalanced current, and a current is established through the sensing circuit to energize the shunt trip of the overload circuit breaker and quickly open the main circuit. A fuse or circuit breaker cannot provide this kind of protection. The fuse or circuit breaker trips or opens the circuit only if a line-to-line or line-to-ground fault occurs that is greater than the circuit protection device rating. Differential transformers continuously monitor circuits to ensure that all current that flows out to motor or appliances returns to the source via the circuit conductors. If any current leaks to a fault, the sensing circuit opens the circuit breaker and stops all current flow. A GFCI does not protect the user from line-to-line or line-to-neutral contact hazards. For example, if an employee using a double-insulated drill with a metal chuck and drill bit protected by a GFCI device drills into an energized conductor and contacts the metal chuck or drill bit, the GFCI device does not trip (unless it is the circuit the GFCI device is connected to) as it does not detect a current imbalance. 4.7.1.2 Uses of GFCIs The use of GFCIs in branch circuits for other than dwelling units is defined in NFPA 70. Ground fault protection for personnel or an assured equipment grounding program shall4.2 be used for temporary wiring installations utilized to supply temporary power to equipment used by personnel during construction, remodeling, maintenance, repair, or demolition activities. For temporary wiring installations: 1. All 120-V, single-phase, 15-, 20-, and 30-A receptacle outlets that are not a part of the permanent wiring of the building or structure, and that are in use by employees, shall4.3 have GFCI protection for personnel. 2. GFCI protection, or an assured equipment grounding program (see Section 5.0) for all other receptacles, shall4.4 be used to protect against electrical shocks and hazards. 3. GFCIs shall4.5 be tested according to the manufacturer’s instructions. 4.7.2 Arc Fault Circuit Interrupters (AFCIs)

A technique for reducing the risk of arc-generated fires is the use of the arc fault current interrupter (AFCI). An AFCI is a device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc fault is detected. AFCIs are evaluated to UL1699, Safety Standard for Arc- Fault Circuit Interrupters, using testing methods that create or simulate arcing conditions to determine the product’s ability to detect and interrupt arcing faults. Although the NEC requires that AFCI protection be provided on branch circuits that supply outlets (receptacle, lighting, etc.) in dwelling units, there is no prohibition against providing AFCI protection on other circuits or locations. 28 DOE-HDBK-1092-2013 4.7.3 Ground Fault Protection for Equipment (GFPE) A GFPE is defined in Article 100 of the NEC as a system intended to provide protection of equipment from damaging line-to-ground fault currents. GFPE systems (equipped with or without a test panel) shall4.6 be inspected and tested at installation and at specified intervals, as recommended by the manufacturer. Figure 4-2 shows a zero-sequence type of ground fault protection. Ground fault protection shall4.7 be provided with 277/480-V, three-phase, four-wire services with overcurrent protection devices (OCPDs) of 1,000 amperes (A) or more. A ground fault sensor (window) can be used to encircle all service conductors, including the grounded conductor (neutral). Fig. 4-2. Example of ground fault protection of equipment. 4.8 OVERCURRENT PROTECTIVE DEVICES Devices, such as fuses and circuit breakers that interrupt current flow through the circuit provide a critical safety function. These circuit elements protect conductor insulation in downstream equipment by limiting the time high currents can flow through the circuit and protect property from fire hazards by interrupting current under overload conditions. These devices may also result in protecting the worker from serious injury. To ensure these protective devices perform effectively, overcurrent protective devices shall4.8 be maintained in accordance with the manufacturers’ instructions or industry consensus standards. 29 DOE-HDBK-1092-2013 5.0 GROUNDING This section presents general rules for the grounding and bonding of electrical installations. Qualified workers should clearly understand the concepts of grounding practices as required by the NEC. They should also clearly understand the definition and intent of the following components of a grounding system that are explained in this section: 1. Grounded conductor 2. Grounding conductor 3. Grounding electrode conductor (GEC) 4. Bonding jumper 5. Grounding electrode 5.1 SPECIFICATIONS AND DRAWINGS Engineering specifications and drawings should identify the requirements for all components and clearly illustrate the grounding electrode system, the GEC, bonding points and bonding jumpers and the connection point for the grounded conductor, as well as the grounding conductors. When used for installation or construction purposes, these specifications and drawings should also include detailed installation instructions. 5.2 CIRCUIT AND SYSTEM GROUNDING Circuit and system grounding consists of connecting the grounded conductor, the equipment grounding conductor (EGC), the grounding bus bars, and all noncurrent-carrying metal parts to ground. This shall5.1 be accomplished by connecting a properly sized continuous GEC between the grounded bus and the grounding electrode system. There are three fundamental purposes for grounding and bonding an electrical system and equipment:

1. To limit excessive voltage from lightning, line surges, and crossovers with higher voltage lines; 2. To keep conductor enclosures and noncurrent-carrying metal enclosures and equipment at zero potential to ground; and 3. To facilitate the opening of OCPDs in case of insulation failures because of faults, short circuits, etc. 5.3 EQUIPMENT GROUNDING Equipment grounding systems, which consist of interconnected networks of EGCs, are used to perform the following functions: 1. Limit the hazard to personnel (shock voltage) from the noncurrent-carrying metal parts of equipment raceways and other conductor enclosures in case of ground faults; and 2. Safely conduct ground-fault current at sufficient magnitude for fast operation of the circuit OCPD. 30 DOE-HDBK-1092-2013 To ensure the performance of the above functions, EGCs shall5.2,5.3,5.4: 1. Be permanent and continuous; 2. Have ample capacity to safely conduct ground-fault current likely to be imposed on them; and 3. Have impedance sufficiently low to limit the voltage to ground to a safe magnitude and to facilitate the operation of the circuit overcurrent protection devices. 5.4 BONDING Caution shall5.5 be taken to ensure that the main bonding jumper and equipment bonding jumper are sized and selected correctly. Bonding completes the grounding circuit so that it is continuous. If a ground fault occurs, the fault current flows and opens the OCPDs. The means of bonding shall5.5 provide the following to ensure the grounding system is intact: 1. Provide a permanent connection; 2. Provide positive continuity at all times; and 3. Provide ampacity to conduct fault current. See Fig. 5-1 which depicts the proper grounding of electrical systems. Circuit and system grounding consists of earth grounding the electrical system at the supply transformer and the line side of the service equipment. Equipment grounding and bonding is accomplished by connecting all metal enclosures and raceways together with the grounding conductors. 31 DOE-HDBK-1092-2013 Fig. 5-1. System grounding in a typical facility. 5.5 GROUNDED OR UNGROUNDED SYSTEMS Ungrounded systems may provide greater continuity of operations in the event of a fault. However, the second fault can most likely be more catastrophic than a grounded system fault. Whenever ungrounded systems are used in a facility, the maintenance personnel shall5.6 receive training in how to detect and troubleshoot the first fault on an ungrounded system. "Grounded" means that the connection to ground between an electrical system conductor and earth has been made. Ungrounded electrical systems are used where the designer does not want the OCPD to clear in the event of a ground fault. The noncurrent-carrying metallic parts of an ungrounded electrical system shall5.7 be grounded. 32 DOE-HDBK-1092-2013 Ground detectors shall5.8 be installed on ungrounded systems per the NEC to sound an alarm or send a message to alert personnel that a first fault has occurred on one of the phase conductors. Ground detectors detect the presence of leakage current or developing fault current conditions while the system is still energized and operating. By warning of the need to take corrective action before a problem occurs, safe conditions can usually be maintained until an orderly shutdown is implemented. 5.5.1 Grounded Systems

Grounded systems are equipped with a grounded conductor that is required5.9 to be run to each service disconnecting means for equipment operating at less than 1000 VAC. The grounded conductor can be used as a current-carrying conductor to accommodate all neutral-related loads. It can also be used to provide an effective ground fault current path on the supply side of the service disconnecting means to clear ground faults. A network of EGCs is routed from the service equipment enclosure to all metal enclosures throughout the electrical system. The EGC carries fault currents from the point of the fault to the grounded bus in the service equipment where it is transferred to the grounded conductor. The grounded conductor carries the fault current back to the source and returns over the faulted phase and trips open the OCPD. Note: A system is considered grounded if the supplying source, such as a transformer or generator, is grounded in addition to the grounding means on the supply side of the service equipment disconnecting device for separately derived systems. The neutral of any grounded system serves two main purposes: (1) it permits the utilization of line-to-neutral voltage and, thus, serves as a current-carrying conductor; and, (2) it plays a vital role in providing a low-impedance path for the flow of fault currents to facilitate the operation of the overcurrent devices in the circuit (see Fig. 5-2). Consideration shall5.10 be given to the sizing of the neutral conductor for certain loads due to the presence of harmonic currents. 33 http:shall5.10 DOE-HDBK-1092-2013 Fig. 5-2. A typical grounded system from a utility service. 5.5.2 Ungrounded Systems Ungrounded systems operate without a grounded conductor. In other words, none of the circuit conductors of the electrical system are intentionally grounded to an earth ground, such as a metal water pipe, or building steel. The noncurrent-carrying conductive materials of an ungrounded electrical system shall5.7 be grounded. The same network of EGCs is provided for ungrounded systems as that for solidly grounded electrical systems. However, EGCs are used only to locate phase-to-ground faults and sound some type of alarm. Therefore, a single sustained line-to-ground fault does not result in an automatic trip of the OCPD. This is a major benefit if electrical system reliability is required, or if it would result in the shutdown of a continuous process. However, if an accidental ground fault occurs and is allowed to flow for a substantial time, overvoltage can develop in the associated phase conductors. Such an overvoltage situation can lead to conductor insulation damage, and while a ground fault remains on one phase of an ungrounded system, personnel contacting one of the other phases and ground are subjected up to 1.732 times the voltage they would experience on a solidly grounded neutral system. (See Fig. 5-3.) 34 DOE-HDBK-1092-2013 Fig. 5-3. An ungrounded system. Note: Ungrounded systems, 120 – 1000 V AC, shall5.8 be equipped with ground detectors and proper maintenance applied to avoid, to the extent practical, the overcurrent of a sustained ground fault on ungrounded systems. If appropriate maintenance is not provided for ungrounded systems, a grounded system should be installed to ensure that ground faults are cleared and circuits, equipment, and personnel are safe. 5.5.3 High-Impedance Grounding

Electrical systems containing three-phase, three-wire loads, as compared to grounded neutral circuit conductor loads, can be equipped with a high-impedance grounded system. High- impedance grounded systems shall5.11 not be used unless they are provided with ground fault indicators or alarms, or both, and unless qualified personnel are available to quickly locate and eliminate such ground faults. Ground faults should be promptly removed or the service reliability could be reduced. See the NEC for requirements on installing a high-impedance grounding system. (See Fig. 5-4.) 35 http:shall5.11 DOE-HDBK-1092-2013 Fig. 5-4. A high-impedance grounding system. 5.6 GROUNDING REQUIREMENTS Alternating current systems of less than 50 V shall5.12 be grounded. Systems of 50 to 1,000 V shall5.13 be solidly grounded. Systems supplying phase-to-neutral loads shall5.11 be solidly grounded (see Fig. 5-5). Solidly grounded means5.14 connected to the earth without inserting any resistance or impedance. The following electrical systems shall5.13 be solidly grounded: 1. 240/120-V, single-phase, three-wire; 2. 208Y/120-V, three-phase, four-wire where there are line-to-neutral loads; 3. 480Y/277-V, three-phase, four-wire where there are line-to-neutral loads; and 4. 240/120-V, three-phase, four-wire, delta (midpoint of one phase used as a grounded circuit conductor). 36 http:shall5.13 http:means5.14 http:shall5.11 http:shall5.13 http:shall5.12 DOE-HDBK-1092-2013 Fig. 5-5. Grounding for systems of 50 to 1,000 V AC. If the following systems are not solidly grounded they shall5.13,5.15 have ground detectors installed: 1. 240-V, three-phase, three-wire delta; 2. 480-V, three-phase, three-wire; 3. 600-V, three-phase, three-wire; and 4. 480-V, three-phase, four-wire where the neutral is not used as a circuit conductor. These electrical systems do not supply phase-to-neutral loads. They supply only phase-to­ phase loads. 5.7 GROUNDING ELECTRODE CONDUCTOR (GEC) The purpose of the GEC is to connect the electrical system to earth ground. In grounded systems, the GEC connects to the neutral bar in the service equipment enclosure. In ungrounded systems, the GEC connects to the grounding terminal bar. It grounds the 37 http:shall5.13,5.15 DOE-HDBK-1092-2013 following items to the grounding electrode system and provides a common reference between earth and: 1. The grounded conductor, if present. 2. The equipment grounding conductor, if present. 3. The metal of conduits, if present. 4. The metal of enclosures, if present. 5. The bonding jumpers bonding together metal enclosures and conduits. 6. The metal enclosure of the service equipment. 5.7.1 Sizing the Grounding Electrode Conductor NEC 250.66 requires the GEC to be sized by the circular mils rating of the largest service entrance conductor or conductors and selected from NEC Table 250.66 based on these values. 5.7.2 Exceptions to NEC 250.66 There is an exception to the main rule. It has three parts and pertains to specific types of grounding electrodes. The exception applies to grounded and ungrounded systems. Exception (A) applies to made electrodes only, such as rod, pipe, or plate electrodes. The GEC is not required to be larger than #6 copper or #4 aluminum. Exception (B) to NEC 250.66 permits a copper conductor not greater than #4 American Wire Gauge (AWG) to be used as a GEC to ground the electrical system to a concrete-encased electrode.

Exception (C) permits a conductor not larger than the ground ring size to be used as a GEC when the electrode is a ground ring. 5.8 MAIN BONDING JUMPER The function of the main bonding jumper is to connect the grounded circuit conductor and the EGC at the service equipment. If the main bonding jumper is left out, there may be no low- impedance circuit for fault current, which poses a potentially dangerous situation. The main bonding jumper shall5.16 connect together the following items within the enclosure for each service disconnect: 1. System grounded conductor; 2. EGCs; and 3. Service disconnect enclosure. If supplied, the manufacturer’s main bonding jumper is the preferred conductor to be used as the main bonding jumper. The NEC requires5.16 the main bonding jumper to be a: (1) wire, (2) screw, (3) bus bar, or (4) a similar suitable conductor. If the bonding jumper is a screw only, it shall5.17 be identified with a green finish that shall5.17 be visible with the screw installed. The NEC requires5.16 the main bonding jumper to be at least the same size as the GEC when the circular mils rating of the service entrance conductors does not exceed 1100 thousand 38 http:requires5.16 http:shall5.17 http:shall5.17 http:requires5.16 http:shall5.16 DOE-HDBK-1092-2013 circular mils (KCmil) for copper or 1750 KCmil for aluminum. For phase conductors greater than 1100 KCmil copper or 1750 KCmil aluminum, the size of the main bonding jumper shall5.18 be not less than 12.5% of the largest phase conductor. 5.9 SYSTEM WITH GROUNDED CONDUCTOR The main purpose of the grounded conductor is to carry unbalanced neutral current under normal operating conditions or fault current in the event that one phase should go to ground. Note: The grounded conductor does not always have to be a neutral conductor. It can be a phase conductor, as when used in a corner grounded delta system. NEC Article 200 provides specific requirements for the use and identification of grounded conductors. In solidly grounded service-supplied systems, the EGS shall5.19 be bonded to the system- grounded conductor and the GEC at the service equipment. The grounded conductor may be used to ground the noncurrent-carrying metal parts of equipment on the supply side of the service disconnecting means per NEC 250.142. The grounded conductor can also serve as the ground fault current return path from the service equipment to the transformer that supplies the service. Generally, the grounded conductor shall5.20 not be used to ground the metal parts of enclosures enclosing conductors and components on the load side of the service. The grounded conductor shall5.21 be connected as follows: 1. The GEC shall5.22 be connected to the grounded (neutral) service conductor. 2. The connection shall5.16 be at an accessible point. The accessible point can be anywhere from the load end of the service drop or service lateral to, and including, the neutral bar in the service disconnecting means or service switchboard. Fig. 5-6 illustrates the use of the grounded conductor. The grounded (neutral) conductor is used to carry normal neutral current or ground fault current in case a ground fault should develop on one of the ungrounded (hot) phase conductors. 39 http:shall5.16 http:shall5.22 http:shall5.21 http:shall5.20 http:shall5.19 http:shall5.18 DOE-HDBK-1092-2013 Fig. 5-6. The grounded neutral conductor.

NEC 250.24 lists the rules for sizing the grounded conductor where it is not used as a grounded neutral circuit conductor. NEC 220.61 gives the rules for calculating and sizing the grounded conductor, when it is used as a circuit conductor. The minimum size for the grounded conductor is the larger of the load calculated by NEC 220.61, or computed as follows: 1. The basic rule is to select the size directly from NEC Table 250.66 when the size of the service-entrance conductors is not larger than 1100 KCmil copper or 1750 KCmil aluminum. 2. When the service entrance conductors are larger than 1100 KCmil copper or 1750 KCmil aluminum, the grounded conductor shall5.16 be 12.5% of the largest phase conductor. 3. When the service phase conductors are paralleled, the size of the grounded conductor shall5.23 be based on the total cross-sectional area of the phase conductors. When installed in two or more raceways, the size of the grounded conductor should be based on the phase conductors, but not smaller than 1/0. 5.10 EQUIPMENT GROUNDING CONDUCTOR EGCs for AC systems, where used, shall5.24 be run with the conductors of each circuit per NEC 300.3, 250.102 (E) and 250.134. Earth and the structural metal frame of a building shall5.25 not be used as the sole EGC for AC systems. 40 http:shall5.25 http:shall5.24 http:shall5.23 http:shall5.16 DOE-HDBK-1092-2013 5.10.1 Sizing the Equipment Grounding Conductor NEC 250.122 lists the requirements for calculating the size of the EGCs in an electrical circuit. There are basically five steps to be applied in sizing, selecting, and routing the EGCs: 1. NEC Table 250.122 shall5.26 be used to size the EGC. 2. When conductors are run in parallel in more than one raceway, the EGC is also run in parallel. Each parallel EGC shall5.27 be sized based on the ampere rating of the overcurrent device protecting the circuit conductors. 3. When more than one circuit is installed in a single raceway, one EGC may be installed in the raceway. However, it shall5.28 be sized for the largest overcurrent device protecting conductors in the raceway. 4. When conductors are adjusted in size to compensate for voltage drop, the EGC shall5.29 also be adjusted in size. 5. The EGC shall5.30 not be required to be larger than the feeder tap conductors. 5.10.2 Separate Equipment Grounding Conductors The possibility of worker exposure to electric shock can be reduced by the use of separate EGCs within raceways. Ground fault current flows through every available path inversely proportional to the impedance of the path. The metallic raceway enclosing the conductors may provide the lowest impedance path sufficient to permit the overcurrent device to operate in a timely manner. However, fittings and raceway systems have been found that are not tightly connected or are corroded and may cause the raceway to present a high impedance path. Therefore, the separate EGC is an assured path for the fault current to travel over and clear the OCPD protecting the circuit. NEC 250.134(B) requires the EGCs to be routed in the same raceway, cable, cord, etc., as the circuit conductors. All raceway systems should be supplemented with separate EGCs. Note: The EGC, where used, shall5.31 be routed with supply conductors back to the source. Additional equipment grounding may be made to nearby grounded structural members or to grounding grids, but this shall5.32 not take the place of the co-routed EGCs. Raceway systems should not be used as the sole grounding conductor.

5.11 UNGROUNDED SYSTEMS Three-phase, three-wire, ungrounded systems (delta), which are extensively used in industrial establishments, shall5.15 not require the use of grounded conductors as circuit conductors. The same network of EGCs shall5.33 be provided for ungrounded systems as those for grounded systems. EGCs in ungrounded systems shall5.34 provide shock protection and present a low- impedance path for phase-to-phase fault currents in case the first ground fault is not located and cleared before another ground fault occurs on a different phase in the system. GECs and bonding jumpers shall5.35 be computed, sized, and installed in the same manner as if the system were a grounded system. Apply all the requirements listed in Section 5.7 for sizing the elements of an ungrounded system. 41 http:shall5.35 http:shall5.34 http:shall5.33 http:shall5.15 http:shall5.32 http:shall5.31 http:shall5.30 http:shall5.29 http:shall5.28 http:shall5.27 http:shall5.26 DOE-HDBK-1092-2013 5.12 GROUNDING A SEPARATELY DERIVED SYSTEM NEC 250.30 covers the rules for grounding separately derived systems. The system grounded conductor for a separately derived system shall5.36 be grounded at only one point. That single system grounding point is at any point from the source of the separately derived system to the first system disconnecting means or overcurrent device. When there is no main system disconnecting means, the connection shall5.36 be made at the source of the system. The grounding electrode for a separately derived system is the nearest of either an effectively grounded structural metal member of the building or an effectively grounded water pipe. If neither is available, concrete-encased electrodes or made electrodes are permitted. In a grounded, separately derived system, the EGCs shall5.36 be bonded to the system- grounded conductor and to the grounding electrode at, or ahead of, the main system disconnecting means or OCPD. The EGC shall5.37 always be bonded to the enclosure of the supply transformer, generator, or converter. The GEC, the system bonding jumper, the grounded conductor, and the EGC are calculated, sized, and selected by the rules listed in Sections 5.7 through 5.10 (see Fig. 5-7). The grounded (neutral) conductor can be used to carry both normal neutral current and abnormal ground fault current. Fig. 5-7. The grounded conductor. 5.13 GROUNDING ELECTRODE SYSTEM NEC 250.52 lists types of electrodes. If one or more are available, they shall5.38 be bonded together to make up the grounding electrode system. The bonding jumper that connects these electrodes shall5.39 be at least as large as the GEC of the system sized by NEC 250.66. The types of electrodes are as follows: 1. A metal water pipe in contact with the earth for 10 feet or more. An interior metal water pipe beyond 5 feet from the point of building entrance shall5.40 not be used as a part of 42 http:shall5.40 http:shall5.39 http:shall5.38 http:shall5.37 http:shall5.36 http:shall5.36 http:shall5.36 DOE-HDBK-1092-2013 the grounding electrode system or, as a conductor to interconnect those electrodes, unless the entire length used as an electrode is exposed. 2. A metal frame of the building or structure, where effectively grounded.5.41 3. A bare #4 conductor at least 20 feet in length and near the bottom of the concrete foundation (within 2 inches), or ½ inch minimum reinforcing steel or rods at least 20 feet in length (one continuous length or spliced together using usual steel tie wires).5.42

4. A bare #2 conductor encircling building at least 20 feet in length and 2.5 feet in the ground.5.43 5. Rod and pipe electrodes at least 8 feet in length.5.44 6. A plate electrode that exposes at least 2 square feet of surface to exterior soil.5.45 7. Other local metal underground systems or structures that are not effectively bonded to a metal water pipe.5.46 The GEC at the service equipment shall5.47 be permitted to be connected to any convenient interbonded electrodes that provide a solid, effective connection where the other electrode(s), if any are properly connected together. (See Fig. 5-8, which illustrates some of the different types of grounding electrodes.) Fig. 5-8. Types of grounding electrodes. 5.14 PERSONNEL PROTECTIVE GROUNDS Personnel working on, or near, de-energized lines or conductors in electrical equipment shall5.48 be protected against shock hazard and flash burns that could occur if the circuit was inadvertently re-energized. Properly installed equipotential protective grounds can aid in lessening the risk of exposure to such hazards by providing additional protection to personnel while they service, repair, and work on such systems. 43 http:shall5.48 http:shall5.47 http:pipe.5.46 http:soil.5.45 http:length.5.44 http:ground.5.43 http:wires).5.42 http:grounded.5.41 DOE-HDBK-1092-2013 5.14.1 Purpose of Personnel Protective Grounds Personnel protective grounds are applied to de-energized circuits to provide a low-impedance path to ground should the circuits become re-energized while personnel are working on or near conductive parts. In addition, the personnel protective grounds provide a means of draining off static and induced voltage from other sources while work is being performed on a circuit (Fig. 5-9 illustrates an example of a personnel protective ground). Fig. 5-9. Equipotential personnel protective grounds. 5.14.2 Criteria for Personnel Protective Grounds Before personnel protective grounds are selected, the following criteria shall5.49 be met for their use, size, and application: 1. A grounding cable shall5.50 have a minimum conductance equal to #2 AWG copper. 2. Grounding cables shall5.51 be sized large enough to carry fault current long enough for the protective devices to sense and the circuit breaker to clear the fault without damage to cable insulation. An example would be a 4/0 Neoprene-insulated welding cable that is capable of passing 30,000 A for 0.5 seconds without melting its insulation. 3. The following are factors that contribute to adequate capacity: a. Terminal strength depends on the ferrules installed on the cable ends. b. Cross-sectional area to carry maximum current without melting. c. Low resistance to keep voltage drop across the areas in which personnel are working at a safe level during any period to prevent re-energization. The voltage 44 http:shall5.51 http:shall5.50 http:shall5.49 DOE-HDBK-1092-2013 drop should not exceed 100 V for 15-cycle clearing times or 75 V for 30-cycle clearing times. d. Verify that the grounding cable and clamp assembly is tested periodically by using the millivolt drop, micro-ohm meter, AC resistance, or DC resistance test methods. For example, if it is desired to maintain a maximum of 100 V across a worker whose body resistance is 1000 ohms, during a fault of 1000 amperes, a personnel protective ground resistance of 10 milliohms, or less, is calculated. 5.14.3 Grounding Clamps

Grounding clamps used in personnel protective grounds are manufactured specifically for this use. The size of grounding clamps shall5.50 match the size of conductor or switchgear bus being grounded. The ground clamp also shall5.50 be rated to handle the full capacity of the available fault currents. Fault currents can typically range in magnitude to over 200,000 A. 5.14.4 Screw-Tightening Devices Approved screw-tightening devices designed for the purpose of pressure metal-to-metal contact are necessary for connections to an adequate system ground. 5.14.5 Grounding Cable Length Grounding cables should be no longer than is necessary, both to minimize voltage drop and to prevent violent movement under fault conditions. For example, as a general rule, grounding cables should not exceed 30 feet for a transmission line and 40 feet for substation use. 5.14.6 Grounding Cable Connection Grounding cables should be connected between phases to the grounded structure and to the system neutral, if present, to minimize the voltage drop across the work area if the circuit should become inadvertently re-energized. Workers shall5.52 install the ground end clamp of a grounding cable first and remove it last. 5.14.7 Connecting Grounding Cables in Sequence Grounding cables shall5.52 be connected to the ground bus, structure, or conductor first, then to the individual phase conductors. The first connection of the grounding cables to the circuit phase conductors should be to the closest phase of the system and, then to each succeeding phase in the order of closeness. 5.14.8 Removing Protective Grounds When removing personnel protective grounds, the order in which they were applied to the phases should be reversed. The grounding cable conductors attached to the ground bus, structure, or conductors shall5.53 always be removed last. 5.14.9 Protective Apparel and Equipment Protective apparel shall5.54 be worn when applying or removing grounds. An insulating tool (hot stick) shall5.52 be used to install and remove grounding cables. 45 http:shall5.52 http:shall5.54 http:shall5.53 http:shall5.52 http:shall5.52 http:shall5.50 http:shall5.50 DOE-HDBK-1092-2013 Protective apparel should include at least the following (see Section 2.11): 1. Safety glasses and, if necessary, a face shield appropriate for existing fault currents; 2. Hardhat (Class E); 3. Appropriate electrical gloves and protectors; and 4. Appropriate AR clothing. 46 DOE-HDBK-1092-2013 6.0 SPECIAL OCCUPANCIES This section covers the specific requirements and information for installing electrical equipment and wiring in explosive and hazardous locations and underground facilities. Classifications of areas or locations with respect to hazardous conditions are covered. Information is provided on the correct methods and techniques needed for system grounding, lightning protection, and controlling of static electricity. This section references DOE, NFPA, and Department of Defense (DoD) standards and manuals. These standards and manuals should be used to ensure safe and reliable installations of electrical equipment and wiring methods in explosive and hazardous locations. 6.1 EXPLOSIVES This section references DOE M 440.1-1, Explosives Safety Manual; NFPA 70; NFPA 77; NFPA 780; and DoD 6055.9-STD, DoD Ammunition and Explosives Safety Standards. As noted above, these standards and manuals should be used to ensure safe and reliable installations of electrical equipment and wiring methods in explosive and hazardous locations.

6.1.1 Evacuation Whenever an electrical storm approaches, personnel shall6.1,6.2 exit any location where a hazard exists from explosives being detonated by lightning. Evacuation may be necessary from locations listed below: 1. All outdoor locations, locations in buildings that do not have lightning protection, and locations within an inhabited building distance of the hazard. (When an electrical storm is imminent, work with explosives operations shall6.2 not be undertaken.); and 2. Locations (with or without lightning protection) where operations use electrostatic- sensitive bulk explosives or electro-explosive devices (EEDs). 6.1.2 Shutdown of Operations The following guidelines shall6.2 be used for shutdown of an operation during an electrical storm: 1. Process equipment containing explosives shall6.2 be shut down as soon as safety permits. 2. When buildings or bays containing explosives are evacuated, functions that cannot be shut down immediately shall6.2 be operated by the minimum number of personnel necessary for safe shutdown. When the operation has been brought to a safe condition, those remaining personnel shall6.2 evacuate. 3. Automatic emergency power equipment shall6.2 be provided if electrical power is critical to an explosives operation during a power shutdown or interruption. 6.1.3 Lightning Protection It is DOE policy to install lightning protection on all facilities used for storage, processing, and handling of explosive materials where operations cannot be shut down and personnel evacuated during electrical storms. Specific operations should be assessed for the risk of detonation of explosives by lightning. Such assessment should consider the need for the protection factors outlined in NFPA 780, Chapter 8. When risk is high, as in operations with highly sensitive electrostatic materials or components, operations should be conducted only in 47 DOE-HDBK-1092-2013 lightning-protected facilities. Approved lightning-protection systems shall6.2 conform to the requirements of NFPA 780, Chapter 8. Lightning-protection systems should be visually inspected every seven months and a report on their conditions filed at least annually. Any evidence of corrosion, broken wires or connections, or any other problem that negates the system's usefulness should be noted and the problem repaired. Lightning-protection systems should be tested electrically every 14 months to ensure testing during all seasons, or immediately following any repair or modification. The testing shall6.3 be conducted only with instruments designed specifically for earth-ground system testing. The instruments should be able to measure 10 ohms ±10% for ground resistance testing and 1 ohm ±10% for bonding testing. Electrical resistance readings should be recorded. Inspection records shall6.4 contain the most recent electrical test report, as well as any subsequent visual inspection reports for each building with a lightning-protection system. 6.1.4 Static Electricity Static electricity shall6.5 be controlled or eliminated in areas where materials are processed or handled that are ignitable by static spark discharge. This category includes spark-sensitive explosives, propellants, and pyrotechnics, as well as solvent vapors and flammable gases. Approved systems to dissipate static electricity should conform to the requirements of DOE M 440.1, Explosives Safety Manual. 6.1.4.1 Bonding and Grounding Equipment

Bonding straps should be used to bridge locations where electrical continuity may be broken by the presence of oil on bearings, or by paint or rust at any contact point. Permanent equipment in contact with conductive floors or tabletops is not considered adequately grounded. Static grounds shall6.6 not be made to: gas, steam, or air lines; dry-pipe sprinkler systems; or, air terminals of lightning-protection systems. Any ground that is adequate for power circuits or lightning-protection is more than adequate for protection against static electricity. 6.1.4.2 Testing Equipment Grounding Systems Grounding systems shall6.7 be tested for electrical resistance and continuity when installation is complete and, in the case of active equipment, at intervals to be locally determined. The grounding system shall6.7 be visually inspected for continuity before it is reactivated, if the equipment has been inactive for more than one month. All exposed explosives or hazardous materials shall6.7 be removed before testing. During a test for resistance to ground, all equipment, except belt-driven machines, should be considered as a unit. In measuring the total resistance to ground for belt-driven machinery (to ensure compliance with Section 6.1.4.3), resistance of the belt is to be excluded. All conductive parts of equipment shall6.8 be grounded so that resistance does not exceed 25 ohms, unless resistance is not to exceed 10 ohms because of the lightning protection system. For existing equipment, the rate of static electricity generation should be considered before changes are made in grounding systems. The resistance of conductive rubber hose should not exceed 250,000 ohms. 6.1.4.3 Conductive Floors, Shoes, Mats, and Wristbands Conductive floors and shoes should be used for grounding personnel conducting operations involving explosives that have an electrostatic sensitivity of 0.1 joule (J) or less. Many 48 DOE-HDBK-1092-2013 flammable liquids and air mixtures can be ignited by static discharge from an individual. In areas where personnel come close enough to have possible contact with static-sensitive explosives or vapors, conductive floors shall6.9 be installed, except where the hazards of dust-air or flammable vapor-air mixtures are eliminated by adequate housekeeping, dust collection, ventilation, or solvent-recovery methods. Conductive floors may also be required where operations are performed involving EEDs that contain a static-sensitive explosive. Conductive floors are not necessary throughout a building or room if the hazard remains localized. In such cases, conductive mats or runners may suffice. These mats or runners shall6.10 be subject to all the specifications and test requirements that apply to conductive floors. Conductive wristbands may be substituted for conductive mats and footwear at fixed, grounded workstations or outdoor locations. 6.1.4.4 Specifications for Conductive Floors and Wristbands Conductive floors shall6.11 be made of non-sparking materials such as conductive rubber, or conductive flooring material, and shall6.11 meet the following requirements: 1. The flooring and its grounding system shall6.12 provide for electrical resistance not to exceed 1,000,000 ohms (measured as specified in Section 6.1.4.5).

2. The surface of the installed floor shall6.13 be reasonably smooth and free from cracks. The material shall6.13 not slough off, wrinkle, or buckle under operating conditions. Conductive tiles are not recommended for use in areas where contamination can be caused by explosive dust. The large number of joints and the tendency of tiles to loosen may provide areas where explosive dust can become lodged and that are not easy to clean with normal cleaning procedures. 3. Where conductive floors and shoes are required, resistance between the ground and the wearer shall6.14 not exceed 1,000,000 ohms, which is the total resistance of conductive shoes on a person plus the resistance of floor to ground. Where conductive floors and shoes are required, tabletops on which exposed explosives or dust are encountered should be covered with a properly grounded conductive material meeting the same requirements as those for flooring. 4. Conductive floors shall6.15 be compatible with the explosive materials to be processed. 5. Conductive wristbands shall6.16 not exceed a resistance of 1,200,000 ohms between the wearer and ground. This resistance shall6.16 be measured with a suitably calibrated ohmmeter. Wristbands shall6.16 be of a design that maintains electrical contact with the wearer when tension is applied to the ground lead wire or the wristband is placed under strain. 6.1.4.5 Conductive Floor Test Before use, tests shall6.17 be conducted on all conductive floors. Subsequent tests shall6.17 be made at least semiannually. Test results shall6.17 be permanently recorded and a copy filed in a central location. Instruments used in testing shall6.17 be used only when the room is free from exposed explosives and mixtures of flammable gases. Maximum floor resistance shall6.18 be measured with a suitably calibrated insulation resistance tester that operates on a normal open-circuit output voltage of 500 V DC and a short-circuit current of 2.5 mA with an effective internal resistance of approximately 200,000 ohms. Minimum floor resistance shall6.18 also be measured with a suitably calibrated ohm meter. 49 http:shall6.18 http:shall6.18 http:shall6.17 http:shall6.17 http:shall6.17 http:shall6.17 http:shall6.16 http:shall6.16 http:shall6.16 http:shall6.15 http:shall6.14 http:shall6.13 http:shall6.13 http:shall6.12 http:shall6.11 http:shall6.11 http:shall6.10 DOE-HDBK-1092-2013 Each electrode shall6.19 weigh 2.3 kilograms (kg) and shall6.19 have a dry, flat, circular contact area 6.5 centimeters (cm) in diameter, which shall6.19 comprise a surface of aluminum or tinfoil 1.3 to 2.5 millimeters (mm) thick, backed by a layer of rubber 0.6 to 0.65 cm thick, and measuring between 40 and 60 durometer hardness as determined with a Shore Type A durometer. The floor shall6.20 be clean and dry. Only electrode jelly should be used to establish a good contact. (Brushless shaving soap and saline solution shall6.20 not be used.) The resistance of the floor shall6.21 be more than 5,000 ohms in areas with 110-V service, 10,000 ohms in areas with 220-V service, and less than 1,000,000 ohms in all areas, as measured between a permanent ground connection and an electrode placed at any point on the floor, and also as measured between two electrodes placed 3 feet apart at any points on the floor. Measurements shall6.21 be made at five or more locations in each room. If the resistance changes appreciably during a measurement, the value observed after the voltage has been applied for about 5 seconds shall6.21 be considered the measured value. (See Fig. 6-1.)

Fig. 6-1. Testing shoes on wearer. 6.1.4.6 Humidification Humidification to prevent accumulations and subsequent discharges of static electricity is usually effective if the relative humidity is above 60%. However, certain materials, such as metallic powders and some pyrotechnic mixtures cannot be exposed to air with 60% relative humidity because of the possibility of spontaneous ignition. Where this technique is used to prevent accumulations of static electricity, a daily check of the humidity levels should be performed before work starts. 6.1.4.7 Ground-Fault Circuit Interrupter GFCI protection should be provided in static-grounded areas where personnel are using hand- held, portable, AC-powered electrical equipment operating at 120 V. 50 http:shall6.21 http:shall6.21 http:shall6.21 http:shall6.20 http:shall6.20 http:shall6.19 http:shall6.19 http:shall6.19 DOE-HDBK-1092-2013 6.1.5 Electrical Equipment and Wiring Electrical equipment and wiring in locations containing explosives shall6.22 comply with relevant provisions of the NEC and DOE regulations, plus the requirements in this section. 6.1.5.1 Hazardous Locations According to DOE M 440.1-1A, Explosives Safety Manual, Revision 9F Chapter II Section 8.0, 8.1d(3), NEC definitions of, and requirements for, hazardous locations Class I and Class II are modified as follows for application to DOE explosives facilities: 1. Areas containing explosive dusts or explosives which may, through handling or processing, produce dust capable of being dispersed in the atmosphere shall6.23 be regarded as Class II Division 1 hazardous locations. 2. Areas that contain exposed explosives, but where no dust hazard exists, shall6.24 be regarded as Class ll Division 2 hazardous locations. 3. Suitable National Electrical Manufacturers Association (NEMA)-rated enclosures shall6.25 (NEC 110.20) be provided in those locations where water/explosives mixtures may contact electrical equipment and wiring. 4. Areas where explosives are processed and sublimation may occur, or where flammable gases or vapor may be present in quantities sufficient to produce explosive or ignitable mixtures, shall6.26 be regarded as Class I Division 1 and Class II Division 1 hazardous locations. 5. To ensure a location is assigned to the proper hazardous location class and division, it is necessary to know the properties of the explosives involved therein, including, at a minimum, sensitivity to heat and spark and thermal stability. If the properties of an explosive area are such that Class II Group G equipment provides inadequate surface temperature limits, special protection shall6.27 be provided or the equipment will be excluded from the hazardous location. This equipment shall6.27 not have a surface temperature exceeding the lowest onset of the exotherm of the explosive as determined by the differential thermal analysis test or the differential scanning calorimetry test. When NEC Class I or II equipment is not available, the substitute equipment shall6.28 be purged or sealed to prevent explosives contamination, shall6.29 be determined intrinsically safe by facility management, or shall6.30 be administratively controlled. If the equipment is purged, it shall6.31 be monitored for flow. 6. Areas that contain explosives that are not defined as hazardous locations (areas containing no dust, vapor, gas hazards, or exposed explosives, such as, storage magazines), should be evaluated and documented by facility management to ensure that electrical ignition sources are minimized or should be regarded as NEC Class II.

7. Procedures shall6.32 be established by each DOE facility to control the use and modification of electrical equipment in explosives areas and ensure that uniform standards are adhered to throughout the facility. 6.1.5.2 Electrical Supply Systems There may be multiple hazards where explosives facilities are located near electrical supply lines. To protect against these hazards, the NESC and the following requirements apply to all new construction or major modification and should be considered for existing facilities: 51 http:shall6.32 http:shall6.31 http:shall6.30 http:shall6.29 http:shall6.28 http:shall6.27 http:shall6.27 http:shall6.26 http:shall6.25 http:shall6.24 http:shall6.23 http:shall6.22 DOE-HDBK-1092-2013 1. Electric lines serving explosive facilities shall6.33 be installed underground from a point not less than 50 feet from such facilities. This also applies to communications and instrumentation lines and security alarm systems. 2. Electric service lines required to be close to an explosives facility shall6.34 be no closer to that facility than the length of the lines between the poles or towers supporting the lines, unless an effective means is provided to ensure that broken, energized lines cannot come into contact with, and present a hazard to, the facility or its appurtenances. 3. Unmanned electrical substations shall6.35 be no closer to explosives facilities than public traffic route distances. 4. Electric transmission lines (carrying 69 kV or more) and the tower or poles supporting them shall6.36 be located not closer to explosives than: a. Inhabited-building distance if the line in question is part of a system serving a large, offsite area. b. Public traffic route distance if loss of the line shall6.36 not create serious social or economic hardships. c. Underground utility separation distance criteria found in Table 6-1. Quantity of explosive Distance, (maximum pounds) m (ft) 100 26 (80) 200 26 (80) 500 26 (80) 1,000 26 (80) 2,000 26 (80) 5,000 26 (80) 10,000 26 (80) 20,000 28 (85) 50,000 36 (110) 100,000 46 (140) 250,000 62 (190) Table 6-1. Quantity-distance separation for protection of underground service installationsa a If the planned building is designed to contain the effects of an explosion, the formula D (distance) = 3.0 w1/3 (w=weight) can be used to determine separation distances for less than 20,000 lb. 6.1.5.3 Building Service Entrance 1. The electrical service entrance for explosives facilities should be provided with: an intermediate, metal-oxide surge lightning arrester on the primary side of the transformer; 2. Surge arresters and surge capacitors on the supply side of the main service disconnect; and 3. Interconnected grounding between the lightning arrester, surge arrester, surge capacitors, service entrance ground, and building ground. 52 http:shall6.36 http:shall6.36 http:shall6.35 http:shall6.34 http:shall6.33 DOE-HDBK-1092-2013 6.1.6 Testing Certain provisions shall6.37 be complied with before tests are performed. Qualified personnel shall6.37 be used to determine the time and procedure of the test. 6.1.6.1 Test Setup In setting up a test at a firing site, all preparatory work should be completed before explosives are received. Such work should include the following items: 1. Checking all firing site safety devices at regular intervals. Such safety devices include warning lights, door and gate firing circuit interlocks, emergency firing circuit cutoff switches, and grounding devices (including those that are remote from the firing bunker).

2. Completing all firing pad and shot stand setup work that requires power tools or other potential spark-producing devices. The firing pad shall6.38 be cleared of all unnecessary gear. Special precautions and procedures shall6.38 be developed and implemented if power tools or other spark-producing devices are needed after the explosive has been received at the firing pad. 3. If a special structure is required, as much work as possible should be accomplished on it, including assembly of all materials. 4. When possible, all diagnostic equipment shall6.39 be set up and checked, and dry runs shall6.39 be performed. 6.1.6.2 Pin Switches and Other Non-initiating Circuits Whenever pin switches and other non-initiating circuits are to be checked (such as for charging current or leakage) and are in contact with, or close to, explosives, the check should be performed remotely. Other non-initiating electrical circuits include strain gauges, pressure transducers, and thermocouples, which may be affixed to, or close to, the explosives within an assembly. If a continuity-only (resistance) check is desired, this may be accomplished as a contact operation with an electrical instrument approved for use with the particular explosive device. When low-firing current actuators are involved, it may be advisable to conduct these tests remotely. 6.1.6.3 Lightning Storms All operations in open test-firing areas shall6.40 be discontinued during lightning storms when explosives are present. Completion of a test after receipt of a lightning alert should be allowed only if test preparation has progressed to the extent that discontinuance of testing would represent a greater personnel risk than would completion of testing. 6.1.6.4 Low-Energy Electro-Explosive Devices When using hot-wire or low-energy EEDs for a test firing, the following requirements shall6.41 be applied: 1. Establishment of procedures to ensure that radio frequency (RF), frequency modulation (FM), and TV transmitters having sufficient output energy to initiate an EED at the test site are either restricted to a safe distance from the site or not operated. Tables 6-2, 6-3, and 6-4 specify minimum safe distances for the various types of transmitters at several output power levels. 53 http:shall6.41 http:shall6.40 http:shall6.39 http:shall6.39 http:shall6.38 http:shall6.38 http:shall6.37 http:shall6.37 DOE-HDBK-1092-2013 Transmitter Power (watts) Minimum Safe Distances (ft) Commercial Amplitude Modulation (AM)broadcast transmitters High Frequency (HF) transmitters other than AM 100 750 750 500 750 1,700 1,000 750 2,400 4,000 750 4,800 5,000 850 5,500 10,000 1,300 7,600 25,000 2,000 12,000 50,000a 2,800 17,000 100,000 3,900 24,000 500,000b 8,800 55,000 a Present maximum power of U.S. broadcast transmitters in commercial AM broadcast frequency range (0.535 to 1.605 MHz). b Present maximum for international broadcast. Table 6-2. Minimum safe distances between RF transmitters and electric blasting operations. Effective Radiation Power (watts) Minimum Safe Distances (ft) Channels 2-6 & FM Channels 7-13 Ultra High Frequency (UHF) Up to 1,000 1,000 750 600 10,000 1,800 1,300 600 100,000a 3,200 2,300 1,100 316,000b 4,300 3,000 1,450 1,000,000 5,800 4,000 2,000 5,000,000c 9,000 6,200 3,500 10,000,000 10,200 7,400 6,000 100,000,000 - - - a Present maximum power, channels 2 to 6 and FM. b Present maximum power, channels 7 to 13. c Present maximum power, channels 14 to 83.

Table 6-3. Minimum safe distances between TV and FM broadcasting transmitters and electric blasting operations. 54 DOE-HDBK-1092-2013 Transmitter Power (watts) Minimum Safe Distances (ft) MFb HFb VHF(1)b VHF(2)b,c UHFb 5a - - - - - 10 50 100 40 90 125 100 40 15 220 90 35 310 130 50 10 20 30 180b - - - 65 40 250 200 490 205 75 45 500c - - 209 - - 600d 300 760 315 115 70 1,000e 400 980 410 150 90 10,000f 1,200 - 1,300 - - MFb 1.6 to 3.4 MHz Industrial HF 28 to 29.7 MHz Amateur VHF(1) 35 to 44 MHz Public use 50 to 54 MHz Amateur VHF(2) 144 to 148 MHz Amateur 150.8 to 161.6 MHz Public use UHF 450 to 460 MHz Public use a Citizens band radio (walkie-talkie), 26.96 to 27.23 MHz and cellular telephones, 3 watts power, 845 MHz; minimum safe distance; 5 feet. b Maximum power for 2-way mobile units in VHF, 15.08- to 161.6-MHz range, and for 2-way mobile and fixed station units in UHF, 450- to 460-MHz range. c Maximum power for major VHF 2-way mobile and fixed-station units in 35- to 44-MHz range. d Maximum power for 2-way fixed-station units in VHF, 150.8- to 161.6-MHz range. e Maximum power for amateur radio mobile units. f Maximum power for some base stations in 42- to 44-MHz band, 1.6- to 1.8- MHz band. Table 6-4. Minimum safe distances between mobile RF transmitters and electric blasting operations. 1. Blasting caps and other low-firing current igniters or detonators shall6.42 be kept separate from explosives at all times, except during actual test charge assembly and setup. 2. The entire wiring system of the explosive charge and of any low-firing-current initiators shall6.43 be kept insulated at all times from every possible source of extraneous current. Shunts shall6.43 be left on all low-energy initiators or lead wires until actual connections are to be made. Connections shall6.43 be taped or otherwise insulated. 3. Test unit low-firing-current actuators or detonators shall6.44 be clearly marked. No contact operations involving electrical testing shall6.44 be permitted on this type of unit unless an electric meter for the specific application is used. 6.1.6.5 Warning Signals Each DOE explosives testing facility shall6.45 use standard audible signals to warn personnel of any impending firing in a test area. Signals shall6.45 be established by each facility and approved by facility management. 55 http:shall6.45 http:shall6.45 http:shall6.44 http:shall6.44 http:shall6.43 http:shall6.43 http:shall6.43 http:shall6.42 DOE-HDBK-1092-2013 6.1.6.6 Firing Leads All detonator lead wires shall6.46 be electrically insulated. Firing leads or cables of low-energy detonators for explosive assemblies shall6.46 be kept properly shorted during setup on the firing point. 6.1.6.7 Electrical Testing Instruments for Use with Explosives Systems Testing instruments shall6.47 meet certain criteria and be certified and labeled for the types of testing they are permitted to perform. 6.1.6.7.1 Classification Testing instruments shall6.48 be assigned to categories on the basis of electrical characteristics that affect their safe use with explosives systems. Specifically, instrument categories shall6.48 be established so that testing instruments in each category can be safely applied to one or more of the following classes of explosives systems: 1. Low-energy or hot-wire initiators (blasting caps, actuators, squibs, etc.); 2. High-energy initiators (exploding bridge wires, slappers, etc.); or 3. Non-initiating electrical circuits.

Testing instruments that do not meet the safety criteria may be used on an explosives system only if the activity is considered a remote operation and adequate personnel shielding or separation distance is provided. 6.1.6.7.2 Certification Each DOE facility using electrical testing instruments on explosives systems shall6.49 establish a formal system for reviewing and certifying those instruments. Procedures for marking instruments to show their approved use, along with restrictions on their use, should also be established, so that every testing instrument is prominently labeled with its approved use and with a warning if there is a restriction on its use. Inspection and calibration of certified instruments shall6.50 be required at prescribed intervals, or whenever the instrument is opened for servicing or repair. Records of all certified testing instruments shall6.51 be maintained by each DOE facility using electrical instruments to test explosives systems. These records should include type, manufacturer, model, electrical specifications, wiring diagrams, and failure mode analyses. 6.1.6.7.3 Electrical Testing Instruments for Use with Initiating Electrical Circuits Instruments used with electrical initiating circuits connected to electro-explosive devices may be further categorized for use with either low-energy initiators or high-energy initiators. All testing instruments used for this purpose shall6.52 be current-limited. Before being used on initiating circuits, every instrument wiring diagram and internal circuitry design shall6.52 be analyzed, examined, and certified for the following: 1. The output current through a resistance equivalent to that of the minimum resistance initiator of the class should not exceed 1% and shall6.53 not exceed 10% of the no-fire rating for the most sensitive initiator of the class. The current-limiting features of the testing instrument shall6.53 be internal to the instrument and shall6.53 not depend on the circuit load characteristics. 56 http:shall6.53 http:shall6.53 http:shall6.53 http:shall6.52 http:shall6.52 http:shall6.51 http:shall6.50 http:shall6.49 http:shall6.48 http:shall6.48 http:shall6.47 http:shall6.46 http:shall6.46 DOE-HDBK-1092-2013 2. The internal circuitry shall6.54 ensure isolation features that require, at a minimum, two independent failure modes before the specified output current can be exceeded. 3. A comprehensive (point-to-point, if possible) wiring check should be made to ensure that the wiring corresponds to the diagram and that all components are functioning properly and within specifications. 6.1.6.7.4 Electrical Testing Instruments For Use With Non-initiating Electrical Circuits Testing instruments in this category are used with electric circuits connected to instruments, such as strain gauges, pin switches, pressure transducers, thermocouples, and electrical components that are affixed to or within an assembly with explosives. These instruments shall6.55 meet the following requirements: 1. Each use of the testing instrument shall6.56 be analyzed to ensure there is no credible scenario in which the normal test energy from the testing instrument can ignite explosive charges or initiators in the test. This testing should be consistent with Section 6.1.6.7.3. 2. Where a testing instrument is used to make measurements on sensors directly applied to explosives (e.g., bonded strain gauges or pin switches), the testing instrument shall6.57

be certified and controlled. 3. Testing instruments shall6.58 be prominently marked with restrictions on their use. Many of these testing instruments do not meet the requirements for use with initiating systems and shall6.58 be marked to prevent their use on this type of circuit. 6.2 PREVENTION OF EXTERNAL IGNITION AND EXPLOSION Explosives can ignite under many conditions, but around electricity they become even more dangerous since an arc, spark, or hot surface can easily touch off an explosion. Therefore, the electrical installation shall6.59 contain these ignition sources or house them in an area well separated from the explosives storage area. The electrical installation shall6.59 prevent accidental ignition of flammable liquids, vapors, and dusts in the atmosphere. In addition, because portable electrical equipment is often used outdoors or in corrosive atmospheres, its material and finish should be such that maintenance costs and shutdowns are minimized. (See Fig. 6-2.) 57 http:shall6.59 http:shall6.59 http:shall6.58 http:shall6.58 http:shall6.57 http:shall6.56 http:shall6.55 http:shall6.54 DOE-HDBK-1092-2013 Fig. 6-2. Electrical sources of ignition. 6.2.1 Sources of Ignition When flammable gases or combustible dusts are mixed in the proper proportion with air, a source of energy is all that is needed to touch off an explosion. One prime source of energy is electricity. During normal operation, equipment such as switches, circuit breakers, motor starters, pushbutton stations or plugs, and receptacles can produce arcs or sparks when contacts are opened and closed, which can easily cause ignition. Other energy hazards are devices that produce heat, such as lighting fixtures and motors. Surface temperatures of these devices may exceed the safe limits of many flammable atmospheres. Finally, many parts of the electrical system can become potential sources of ignition in the event of insulation failure. Included in this category are wiring (particularly splices), transformers, impedance coils, solenoids, and other low-temperature devices without make-or-break contacts. Non-electrical sources, such as sparks from metal can also easily cause ignition. A hammer, file, or other tool dropped on masonry, or on a nonferrous surface, could be a hazard, unless it is made of non-sparking material. For this reason, portable electrical equipment is usually made from aluminum or other material that does not produce sparks if it is dropped. 6.2.2 Combustion Principles The following three basic conditions are necessary for a fire or explosion to occur: 1. A flammable liquid, vapor, or combustible dust is present in sufficient quantity; 2. A flammable liquid, vapor, or combustible dust mixes with air or oxygen in the proportion necessary to produce an explosive mixture; and 3. A source of energy is applied to the explosive mixture. In applying these principles, the quantity of the flammable liquid or vapor that may be liberated and its physical characteristics are taken into account. Also, vapors from flammable liquids have a natural tendency to disperse into the atmosphere and rapidly become diluted to concentrations below the lower explosion limit, particularly when there is natural or mechanical ventilation. Finally, the possibility that the gas concentration may be above the upper explosion 58 DOE-HDBK-1092-2013 limit does not ensure any degree of safety since the concentration first passes through the explosive range to reach the upper explosion limit.

6.2.3 Evaluation of Hazardous Areas Each area that contains gases or dusts that are considered hazardous shall6.59 be carefully evaluated to make certain that the correct electrical equipment is selected. Many hazardous atmospheres are Class I Group D or Class II Group G. However, certain areas may involve other groups, particularly Class I Groups B and C. Conformity with the NEC requires the use of fittings and enclosures approved for the specific hazardous gas or dust involved. A person cognizant of the requirements should make the determination of the area classification wiring and equipment selection for Class I, II, and III areas. The determination of the area classification, wiring, and equipment selection for Class I, Zone 0, 1, and 2 areas shall6.60 be under the supervision of a qualified person. 6.2.4 Intrinsically Safe Equipment The use of intrinsically safe equipment is primarily limited to process control instrumentation because these electrical systems lend themselves to the low energy requirements. The installation rules are covered in Article 504 of the NEC. The definition of intrinsically safe equipment and wiring is, "Equipment and wiring that are incapable of releasing sufficient electrical energy under normal or abnormal conditions to cause ignition of a specific hazardous atmospheric mixture in its most easily ignited concentration." The UL and the Factory Mutual list several devices in this category. The equipment and its associated wiring shall6.61 be installed such that they are positively separated from the non-intrinsically safe circuits. Induced voltages could defeat the concept of intrinsically safe circuits. 6.2.5 Enclosures In Class I Division 1 and 2 locations, conventional relays, contactors, and switches that have arcing contacts shall6.62 be enclosed in explosion-proof housings, except for those few cases where general-purpose enclosures are permitted by the NEC. By definition, enclosures for these locations shall6.63 prevent the ignition of an explosive gas or vapor that may surround it. In other words, an explosion inside the enclosure should not start a larger explosion outside. Adequate strength is necessary for such an enclosure. For an explosion-proof enclosure, a safety factor of 4 is used. That is, the enclosure should withstand a hydrostatic pressure test of four times the maximum pressure from an explosion within it. In addition to being strong, the enclosure should be flame-tight. This term does not imply that the enclosure is hermetically sealed, but rather that the joints cool the hot gases resulting from an internal explosion so that, by the time they reach the outside hazardous atmosphere, they are too cool to affect ignition. The strains and stresses caused by internal explosive pressures are illustrated in Fig. 6-3 (dotted lines indicate the shape that a rectangular enclosure strives to attain under these conditions). Openings in an enclosure strive to maintain the shape of the enclosure. Openings in an explosion-proof enclosure can be threaded-joint type or flat-joint type. Threaded joints can be used as an escape path to cool the hot gases as they pass through the threads to the outside of the enclosure (Fig. 6-4). Flat joints in an explosion-proof enclosure are illustrated in Fig. 6-5. In Class II locations, the enclosure should keep dust out of the interior and operate at a safe surface temperature. Because there are no internal explosions, the enclosure may have thinner wall sections. The construction of these enclosures is known as dust-ignition-proof.

59 http:shall6.63 http:shall6.62 http:shall6.61 http:shall6.60 http:shall6.59 DOE-HDBK-1092-2013 Fig. 6-3. Strains and stresses caused by an internal explosion. Fig. 6-4. Threaded joints in an explosion-proof enclosure. 60 DOE-HDBK-1092-2013 Fig. 6-5. Flat joints in an explosion proof enclosure. 6.2.6 Purging/Pressurization Systems Purging/pressurization systems permit the safe operation of electrical equipment under conditions of hazard for which approved equipment may not be commercially available. For instance, most switchgear units and many large motors do not come in designs listed for Class I Groups A and B. Whether cast-metal enclosures or sheet-metal enclosures with pressurization should be used for hazardous locations is mainly a question of economics, if both types are available. As a typical example, if an installation had many electronic instruments that could be enclosed in a single sheet-metal enclosure, the installation lends itself to the purging/pressurization system. However, if the electronic instruments require installation in separate enclosures, use of the cast metal in hazardous-location housing would almost invariably prove more economical. Pressurized enclosures need: 1. A source of clean air or inert gas; 2. A compressor to maintain the specified pressure on the system; and 3. Pressure control valves to prevent the power from being applied before the enclosures have been purged and to de-energize the system should pressure fall below a safe value. In addition, door-interlock switches prevent access to the equipment while the circuits are energized. All of these accessories can add up to a considerable expenditure. For a detailed description of purging/pressurizing systems see NFPA 496, Purged and Pressurized Enclosures for Electrical Equipment in Hazardous Classified Locations. 61 DOE-HDBK-1092-2013 6.3 HAZARDOUS LOCATIONS Group, class, and division classify hazardous areas and locations. The atmospheric mixtures of various gases, vapors, dust, and other materials present determine these classifications. The intensity of the explosion that can occur depends on concentrations, temperatures, and many other factors that are listed in OSHA and NFPA codes and standards. It is important that hazardous locations are well understood by anyone designing, installing, working on, or inspecting electrical equipment and wiring in such areas. Such locations carry a threat of flammable or combustible gases, vapors, or dusts being present some, or all, of the time. Information in this section assists in classifying areas or locations with respect to hazardous conditions, whether from atmospheric concentrations of hazardous gases, vapors, and deposits, or from accumulations of readily ignitable materials. This section covers the requirements for electrical equipment and wiring in locations that are classified according to the properties of the flammable vapors, liquids, or gases or combustible dusts that may be present and the likelihood that a flammable or combustible concentration is present. The hazardous (classified) locations are assigned the following designations: 1. Class I Division 1 2. Class I Division 2 3. Class II Division 1 4. Class II Division 2 6.3.1 Class I Class I locations are identified in the NEC as those in which flammable gases or vapors are, or may be, present in the air in amounts sufficient to create explosive or ignitable mixtures. Gases or vapors may be continuously or intermittently present. However, if a gas or vapor is present, there is a potential that a flammable mixture also is present.

From an engineering standpoint, greater precautions are needed if a particular set of conditions is likely to occur (e.g., the presence of a flammable mixture within the explosive range) than if it is unlikely. This is the reason for dividing hazardous locations into two divisions. 6.3.1.1 Class I Division 1 NEC 500.5 defines Class I Division 1 hazardous locations as those in which: 1. Ignitable concentrations of flammable gases, liquids, or vapors can exist under normal operating conditions; 2. Ignitable concentrations of such gases or vapors may exist frequently because of repair or maintenance operations or because of leakage; or 3. Breakdown or faulty operation of equipment or processes might release ignitable concentrations of flammable gases, liquids, or vapors and might also cause simultaneous failure of electrical equipment. Note: In each case, ignitable concentrations are mentioned. This means concentrations between the lower- and upper-flammable or explosion limits. (See Section 6.3.5 and Table 6-5.) 62 DOE-HDBK-1092-2013 The fine-print note to NEC 500.5(B)(1) describes a number of areas and occupancies normally classified as Class I Division 1 locations. NEC Article 100 defines a volatile flammable liquid as one that has a flashpoint below 38°C (100°F) or one whose temperature is raised above its flashpoint. Flashpoint is the lowest temperature to which a combustible or flammable liquid may be heated before sufficient vapors are driven off and the liquid is capable of ignition when brought into contact with a flame, arc, spark, or another ignition source. (See Section 6.3.6 and Section 1-3 of NFPA 497M, Classification of Gases, Vapors and Dust for Electrical Equipment in Hazardous Classified Locations, for more details.) 63 DOE-HDBK-1092-2013 Group3 Atmosphere Ignition1 Temp °F °C Ignition2 energy (millijoules) Flammable limits3 (% by volume) Lower Upper Flashpoint3 °F °C NEMA enclosure4 classification Indoor Outdoor A Acetylene 581 305 0.017 2.5 100.0 Gas Gas 7 8 B 1,3-butadiene 788 420 - 2.0 12.0 Gas Gas 7 8 B Ethylene oxide 804 429 - 3.0 100.0 -20 -28 7 8 B Hydrogen 968 520 0.017 4.0 75.0 Gas Gas 7 8 B Manufactured gas containing - - - - - - - - - more than 30% hydrogen by volume B Propylene oxide 840 449 - 2.6 36.0 -35 -37 7 8 C Acetaldehyde 347 175 - 4.0 60.0 -38 -39 7 9 C Diethyl ether 320 160 - 1.9 36.0 -49 -45 7 8 C Ethylene 842 450 0.08 2.7 36.0 Gas Gas 7 8 C Unsymmetrical dimethyl 480 249 - 2.0 95.0 5 -15 7 8 hydrazine (UDMH) D Acetone 869 465 - 2.5 13.0 -4 -20 7 8 D Acrylonitrile 898 481 - 3.0 17.0 32 0 7 8 D Ammonia 928 498 - 15.0 28.0 Gas Gas 7 8 D Benzene 928 498 - 1.3 7.9 12 -11 7 8 D Butane 550 288 - 1.6 8.4 Gas Gas 7 D 1-butanol 650 343 - 1.4 11.2 98 37 7 8 D 2-butanol 761 405 - 1.7@212°F 9.0@212°F 75 24 7 8 D n-butyl acetate 790 421 - 1.7 7.6 72 22 7 8 D Cyclopropane 938 503 0.25 2.4 10.4 Gas Gas 7 8 D Ethane 882 472 - 3.0 12.5 Gas Gas 7 8 D Ethanol 685 363 - 3.3 19.0 55 13 7 8 D Ethylacetate 800 427 - 2.0 11.5 24 -4 7 8 D Ethylene dichloride 775 413 - 6.2 16.0 56 13 7 8 D Gasoline 536 to 280 to - 1.2 to 1.5 7.1 to 7.6 7 8 7 8 880 471 D Heptane 399 204 - 1.05 6.7 -36 to -38 to ­ 7 8 -50 46 64 DOE-HDBK-1092-2013 Ignition2 NEMA Flammable limits3 Ignition1Temp. Energy Flashpoint3 enclosure4 Group3 Atmosphere (% by volume) (millijoules) classification

°F °C Lower Upper °F °C Indoor Outdoor D Hexane 437 225 - 1.1 7.5 -7 -22 7 8 D Isoamyl alcohol 662 350 - 1.2 9.0@212°F 109 43 7 8 D Isoprene 428 220 - 1.5 8.9 -65 -54 7 8 D Methane 999 630 0.30 5.0 15.0 Gas Gas 7 8 D Methanol 725 385 - 6.0 36.0 52 11 7 8 D Methyl ethyl ketone 759 404 - 1.7@200°F 11.4@200°F 16 -9 7 8 D Methyl isobutyl ketone 840 449 - 1.2@200°F 8.0@200°F 64 18 7 8 D 2-methyl-l-propanol 780 416 - 1.7@123°F 10.6@202°F 82 28 7 8 D 2-methyl-2-propanol 892 478 - 2.4 8.0 52 11 7 8 D Naphtha (petroleum) 550 288 - 1.1 5.9 <0 <-18 7 8 D Octane 403 206 - 1.0 6.5 56 13 7 8 D Pentane 470 243 - 1.5 7.8 < -40 < -40 7 8 D 1-pentanol 572 300 - 1.2 10.0@212°F 91 33 7 8 D Propane 842 450 0.25 2.1 9.5 Gas Gas 7 8 D 1-propanol 775 413 - 2.2 13.7 74 23 7 8 D 2-propanol 750 399 - 2.0 12.7@200°F 54 12 7 8 D Propylene 851 455 - 2.0 11.1 Gas Gas 7 8 D Styrene 914 490 - 1.1 7.0 88 31 7 8 D Toluene 896 480 - 1.2 7.1 40 4 7 8 D Vinyl acetate 756 402 - 2.6 13.4 18 -8 7 8 D Vinyl chloride 882 472 - 3.6 33.0 Gas Gas 7 8 D Xylenes 867 to 984 464 to 529 - 1.0 to 1.1 7.6 81 to 27 to 7 8 90 32 Notes: 1 See NFPA 325 and 497M. 2 See Handbook of Fire Protection Engineering, Society of Fire Protection Engineers. 3 See NFPA 325. 4 See NEMA 250, Enclosures for Electrical Equipment. Table 6-5. Class I Division 1 and Class I Division 2 summary of selected hazardous atmospheres. 65 mailto:12.7@200�F mailto:10.0@212�F mailto:10.6@202�F mailto:1.7@123�F mailto:8.0@200�F mailto:1.2@200�F mailto:11.4@200�F mailto:1.7@200�F mailto:9.0@212�F DOE-HDBK-1092-2013 6.3.1.2 Class I Division 2 NEC 500.5(B)(2) defines Class I Division 2 locations as those: 1. In which flammable liquids or gases are handled, processed, or used, but where such materials are normally confined in closed containers or closed systems from which they can escape only in case of accidental rupture or breakdown of such containers or systems, or in case of abnormal equipment operation; 2. In which gases or vapors are normally prevented, by positive mechanical ventilation, from forming ignitable concentrations and that might become hazardous through failure or abnormal operation of the ventilating equipment; or 3. That are adjacent to a Class I Division 1 location and to which ignitable concentrations of gases or vapors might occasionally be transmitted, unless such transmittal is prevented by adequate positive-pressure ventilation from a source of clean air, and effective safeguards against ventilation failure are provided. The fine-print note #2 to NEC 500.5 describes a number of areas and occupancies normally classified as Class I Division 2 locations. For example, piping systems without valves, meters, and devices do not usually cause a hazardous condition, even though they carry flammable liquids, because they are considered a contained system. Therefore, the surrounding area can be classified as a Class I Division 2 location. 6.3.2 Class II A Class II location is defined in NEC 500 as an area where combustible dust presents a fire or explosion hazard. Class II locations are divided into two divisions based on the normal presence or absence of dust. 6.3.2.1 Class II Division 1 A Class II Division 1 location is one: 1. In which combustible dust is in the air under normal operating conditions in quantities sufficient to produce explosive or ignitable mixtures;

2. Where mechanical failure or abnormal operation of machinery or equipment might cause such explosive or ignitable mixtures to be produced and might also provide a source of ignition through simultaneous failure of electrical equipment, operation of protective devices, or other causes; or 3. In which combustible dusts of an electrically conductive nature may be present in hazardous quantities. (See Table 6-6.) 66 DOE-HDBK-1092-2013 Class Division II 1 Combustible (Normally dust hazardous) 2 (Not normally hazardous) Temperature, Group atmosphere Eb Atmospheres containing combustible dusts regardless of resistivity, or other combustible dusts of similarly hazardous characteristics having resistivity of less than 102 ohm- centimeter Fb Atmospheres containing carbonaceous dusts having resistivity between 102 and 108 ohm-centimeter Gb Atmospheres containing dusts having resistivity of 108 ohm-centimeter F Atmospheres containing dusts having resistivity of 105 ohm-centimeter G Same as Division 1 Covered Devices not subject to overloads (switches, meters) Devices subject to overload (motors, transformers) Lighting fixtures Measured Maximum ambient temperature in 40°C ambient with a dust blanket Maximum external temperature under conditions of use Limiting value Should be less than ignition- temperature dust but not more than: No overload: E—200°C (392°F) F—200°C (392°F) G—165°C (329°F) Possible overload in operation: