ELECTRICAL SAFETY HANDBOOK John Cadick, P.E. Mary Capelli-Schellpfeffer, M.D., M.D., M.P M.P.A. .A. Dennis K. Neitzel, C.P.E. Al Winfield
Fourth Edition
New York Chicago San Francisco Lisbon London Madrid Mexico City Milan New Delhi San Juan Seoul Singapore Sydney Toronto
Copyright © 2012 by The McGraw-Hill Companies. All All rights reserved. Except as permitted under the United States Copyright Act Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher publi sher.. ISBN: 978-0-07-174514-7 MHID: 0-07-174514-9 The material in this eBook also appears in the print version of this title: ti tle: ISBN: 978-0-07-174513-0, MHID: 0-07-174513-0. McGraw-Hill eBooks are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs. To To contact a representative please e-mail us at bulksales@mcgraw-hill. com. All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occurrence of a trademarked name, we use names in an editorial fashion only, and to the benefit of the trademark owner, owner, with no intention of infringement of the trademark. Where such designations appear in this book, they have been printed with initial caps. Information has been obtained by McGraw-Hill from sources believed to be reliable. However, However, because of the possibility of human or mechanical error by our sources, McGraw-Hill, or others, McGraw-Hill does not guarantee the accuracy, accuracy, adequacy, adequacy, or completeness of any information and is not responsible for any errors or omissions or the results obtained from the t he use of such information. TERMS OF USE This is a copyrighted work and The McGraw-Hill Companies, Inc. (“McGrawHill”) and its licensors reserve all rights in and to the work. Use of this work is subject to these terms. Except as permitted under the Copyright Act of 1976 and the right to t o store and retrieve one copy of the work, you may not decompile, disassemble, reverse engineer, engineer, reproduce, modify, create derivative works based upon, transmit, distribute, di stribute, disseminate, sell, publish or sublicense the work or any part of it without McGraw-Hill’s McGraw-Hill’s prior consent. You You may use the work for your own noncommercial and personal use; any other use of the work is strictly prohibited. Your Your right to use the work may be terminated if you fail to comply with these terms. THE WORK IS PROVIDED “AS IS.” McGRAW-HILL AND ITS LICENSORS MAKE NO GUARANTEES OR WARRANTIES AS TO THE ACCURACY, ADEQUACY OR COMPLETENESS OF OR RESULTS TO BE OBTAINED OBTAINED FROM USING THE WORK, INCLUDING I NCLUDING ANY INFORMA INFORM ATION THAT THAT CAN BE ACCESSED THROUGH THE WORK VIA HYPERLINK OR OTHERWISE, AND EXPRESSLY DISCLAIM ANY WARRANTY, ARRANTY, EXPRESS EXPRE SS OR IMPLIED, INCLUDING INCL UDING BUT NOT NO T LIMITED TO IMPLIED IM PLIED WARRANTIES WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. McGraw-Hill and its licensors do not warrant or guarantee that the functions contained in the work will meet your requirements or that its operation will be uninterrupted or error free. Neither McGraw-Hill nor its licensors shall be l iable to you or anyone else for any inaccuracy i naccuracy,, error or omission, regardless of cause, in the t he work or for any damages resulting therefrom. McGraw-Hill has no responsibility for the content of any information accessed through the work. Under no circumstances shall McGraw-Hill and/or its licensors be liable for any i ndirect, incidental, special, punitive, consequential or similar damages that result from the use of or inability to use the work, even if any of them has been advised of the possibility of such damages. This limitation of liability shall apply to any claim or cause whatsoever whether such claim or cause arises in contract, tort or otherwise.
To my entire family, for their love, support, and willingness to sometimes overlook what I am, in favor of what what I try to be. be. Also to my coauthors—I coauthors—I am honored and proud to work with each and every one of you. John Cadick
In dedication dedication to Michael Michael Allen, Allen, Sarah, Sarah, Benjamin, Benjamin, Amelia, and Natalie, Natalie, with with all my love. love. Mary Capelli-Schellpfeffer Capelli-Schellpfeffer
To my wife, Brenda Neitzel, who always believed in me and encouraged me to continue my education and strive to be the best that I could be; to the U.S. Air Force for giving me my start in an electrical career in 1967; to all of my employers, who gave me countless opportunities to learn and progress; and to John Cadick, who believed in me enough to ask me to contribute to this book. Dennis K. Neitzel
I dedi dedicat catee this this effor effortt to to Gerr Gerryy, my wife wife and best best frie friend, nd, for her endles e ndlesss love, lov e, support su pport,, encourageme en couragement, nt, and belief in me. It is my honor to have John Cadick as a cherished friend and coworker. coworker. The confidence John Cadick has shown in me by inviting my contribution to this esteemed project is deeply appreciated. Al Winfield
ABOUT THE AUTHORS John Cadick, P.E., is a registered professional engineer and the founder and president of the Cadick Corporation. Mr. Cadick has specialized for more than four decades in electrical engineering, training, and management. His consulting firm, based in Garland, Texas, specializes in electrical engineering and training and works extensively in the areas of power systems design and engineering studies, condition-based maintenance programs, and electrical safety. Prior to creating the Cadick Corporation and its predecessor, Cadick Professional Services, he held a number of technical and managerial positions with electric utilities, electrical testing companies, and consulting firms. In addition to his consulting work in the electrical power industry, Mr. Cadick is the author of numerous books, professional articles, and technical papers. Mary Capelli-Schellpfeffer, M.D., M.P.A., delivers outpatient medical care services to employees in occupational health service centers. Board-certified as a physician in general preventive medicine and public health, she is also a consultant to both the NJATC (National Joint Apprenticeship and Training Committee of the National Electrical Contractors Association and International Brotherhood of Electrical Workers) and IEEE (Institute of Electrical and Electronics Engineers) Standards Committees. She lives in Chicago, Illinois. Dennis K. Neitzel, C.P.E., has specialized in training and safety consulting in electrical power systems and equipment for industrial, government, and utility facilities since 1967. He is an active member of IEEE, ASSE, AFE, IAEI, and NFPA. He is a certified plant engineer (C.P.E.) and a certified electrical inspector general; principal committee member and special expert for the NFPA 70E, Standard for Electrical Safety in the Workplace; serves on the Defense Safety Oversight Council—Electrical Safety Working Group for the U.S. Department of Defense Electrical Safety Special Interest Initiative; serves as working group chairman for the revision of IEEE Std. 902 (The Yellow Book), IEEE Guide for Maintenance, Operation, and Safety of Industrial and Commercial Power Systems (changing to IEEE 3007.1, 3007.2, and 3007.3); and serves as working group chairman for IEEE P45.5 Recommended Practice for Electrical Installations on Shipboard—Safety Considerations. He earned his bachelor’s degree in electrical engineering management and his master’s degree in electrical engineering applied sciences. Mr. Neitzel has authored, published, and presented numerous technical papers and magazine articles on electrical safety, maintenance, and training. Al Winfield has more than 50 years of hands-on electrical construction, repair, system operations, and training experience. Mr. Winfield started his career in the electrical industry in 1960. During his career in the public utility industry, his experience included hands-on electrical work as a high-voltage lineman, operations experience in system operations, and several years as the supervisor of training—system operations. He has specialized in providing technical and safety training for electrical system operations personnel and electrical construction and maintenance personnel for the past three decades. Over the past two decades, Mr. Winfield has also provided electrical consulting services for several manufacturing, mining, and petrochemical corporations around the world. He is currently the director of safety and training for Cadick Corporation.
CONTENTS
Foreword xv Preface xvii Acknowledgments
xx
Chapter 1. 1. Hazards of Electricity Electricity
1.1
Introduction / 1.1 Hazard Analysis / 1.1 Shock / 1.1 Description / 1.1 Influencing Factors / 1.2 Arc / 1.7 Definition and Description Description / 1.7 Arc Energy Energy Release / 1.8 Arc Energy / 1.8 Arc Energy Energy Input / 1.11 Arcing Voltage / 1.12 Arc Surface Surface Area / 1.12 Incident Energy / 1.13 Arc Burns / 1.15 Blast / 1.15 Affected Body Parts / 1.18 General / 1.18 Skin / 1.18 The Nervous System / 1.20 Muscular System / 1.21 The Heart / 1.21 The Pulmonary Pulmonary System / 1.22 Summary of Causes—Injury Causes—Injury and Death / 1.23 Shock Effect / 1.23 Arc-Flash Effect / 1.23 Causes of Injury Injury / 1.24 Causes of Death / 1.24 Protective Protective Strategies / 1.24 References / 1.25
Chapter 2. Basic Physics Physics of Electrical Hazards Hazards Introduction / 2.1 Electromagnetism / 2.1 Introduction / 2.1 The Four Fundamental Fundamental Forces (Interactions) (Interactions) of Nature / 2.1 The Electromagnetic Electromagnetic Spectrum / 2.4
v
2.1
vi
CONTENTS
Electrical Properties Properties of Materials / 2.5 Conductors / 2.5 Nonconductors / 2.7 Physics Considerations Considerations in Electrical Fault Fault Conditions / 2.8 Risks / 2.8 Bolted Fault / 2.8 Arcing Fault / 2.9 Review of Foundational Foundational Approaches Approaches to Interpreting Arcing Phenomena / 2.11 Summary / 2.15 References / 2.15
Chapter 3. Electrical Safety Equipment Introduction / 3.1 General Inspection and Testing Requirements for Electrical Safety Equipment / 3.1 Flash and Thermal Protection Protection / 3.2 A Note on When When to Use Thermal Protective Protective Clothing / 3.2 Thermal Performance Performance Evaluation Evaluation / 3.2 Clothing Materials / 3.4 Non-FlameNon-Flame-Resistant Resistant Materials / 3.4 Flame-Resistant Flame-Resistant Materials / 3.5 Work Clothing / 3.6 Flash Suits / 3.9 Head, Eye, and Hand Protection / 3.9 Head and Eye Protection Protection / 3.10 Hard Hats / 3.10 Safety Glasses, Goggles, and Face Face Shields / 3.12 Rubber Insulating Equipment / 3.13 Rubber Gloves / 3.14 Rubber Mats / 3.17 Rubber Blankets / 3.18 Rubber Covers / 3.21 Line Hose / 3.22 Rubber Sleeves / 3.23 In-Service Inspection and Periodic Testing of Rubber Goods / 3.25 Hot Sticks / 3.41 Description and Application / 3.41 When to Use / 3.43 How to Use / 3.43 Testing Requirements Requireme nts / 3.44 Insulated Insulate d Tools / 3.44 Description and Application / 3.44 When to Use / 3.45 How How to Use and Care For / 3.45 Barriers and Signs Signs / 3.46 Barrier Tape / 3.46 Signs / 3.46 When and How How to Use / 3.46 Safety Tags, Locks, and Locking Devices / 3.48 Safety Tags / 3.48 Locks and Multiple-Lock Multiple-Lock Devices Devices / 3.48 Locking Devices / 3.49 When and Where to Use Lockout-Tagout / 3.51 Voltage-Measuring oltage- Measuring Instruments Instrument s / 3.51 Safety Voltage Measurement / 3.51 Proximity Proximit y Testers / 3.52
3.1
CONTENTS
vii
Contact Testers / 3.53 Selecting Selecti ng Voltage-Measuring oltage- Measuring Instruments / 3.55 Instrument Condition / 3.55 Low-Voltage Low-Voltage Voltmet Voltmeter er Safety Standards / 3.57 Three-Step Three-Ste p Voltage Measurement Process / 3.57 General Considerations for Low-Voltage Measuring Instruments / 3.59 Safety Grounding Grounding Equipment / 3.60 The Need for for Safety Grounding Grounding / 3.60 Safety Grounding Grounding Switches Switches / 3.60 Safety Grounding Grounding Jumpers / 3.62 Selecting Safety Grounding Jumpers Jumpers / 3.64 Installation and Location Location / 3.68 Ground-Fault Ground-Fault Circuit Interrupters / 3.71 Operating Principles / 3.71 Applications / 3.72 Arc-Fault Circuit Interrupters Interrupters / 3.73 Safety Electrical Electrical One-Line Diagram / 3.74 The Electrician’s Electrician’s Safety Kit / 3.74 References / 3.78
Chapter 4. Safety Procedures Procedures and Methods Introduction / 4.1 The Six-Step Six-Step Safety Method / 4.1 Think—Be Aware / 4.2 Understand Your Procedures / 4.2 Follow Your Procedures / 4.2 Use Appropriate Safety Safety Equipment / 4.2 Ask If You You Are Unsure, and Do Not Assume / 4.2 Do Not Answer If You Do Not Know / 4.3 Job Briefings / 4.3 Definition / 4.3 What Should Be Included? Included? / 4.3 When Should Job Job Briefings Be Held? / 4.3 Energized or De-Energized? De-Energized? / 4.3 The Fundamental Fundamental Rules / 4.3 A Hot-W Hot-Work Decision Tree / 4.4 After the Decision Decision Is Made / 4.6 Safe Switching of of Power Systems / 4.6 Introduction / 4.6 Remote Operation / 4.7 Operating Medium-Voltage Medium-Voltage Switchgear / 4.11 Operating Operatin g Low-Voltage Low-Voltage Switchgear / 4.15 Operating Molded-Case Molded-Case Breakers and Panelboards Panelboards / 4.19 Operating Enclosed Switches and Disconnects Disconnects / 4.21 Operating Open-Air Disconnects / 4.23 Operating Motor Starters / 4.26 Energy Control Programs Programs / 4.27 General Energy Energy Control Programs Programs / 4.28 Specific Energy Energy Control Programs / 4.28 Basic Energy Energy Control Control Rules / 4.28 Lockout-Tagout / 4.30 Definition and Description Description / 4.30 When to Use Locks and Tags Tags / 4.31 Locks without Tags Tags or Tags Tags without Locks / 4.31 Rules for Using Locks and Tags Tags / 4.31
4.1
viii
CONTENTS
Responsibilities of Employees Employees / 4.32 Sequence / 4.32 Lock and Tag Application Applicati on / 4.33 Isolation Isolatio n Verification erificati on / 4.33 Removal of Locks and Tags Tags / 4.33 Safety Ground Ground Application / 4.34 Control Transfer / 4.34 Nonemployees Nonemployees and Contractors / 4.36 Lockout-Tagout Training / 4.36 Procedural Reviews Reviews / 4.36 Voltage-Measurement oltage-Me asurement Techniques / 4.37 Purpose / 4.37 Instrument Selection / 4.37 Instrument Condition / 4.38 Three-Step Measurement Measurement Process Process / 4.39 What to Measure Measure / 4.39 How to Measure / 4.41 Placement of Safety Grounds Grounds / 4.42 Safety Grounding Grounding Principles / 4.42 Safety Grounding Grounding Location / 4.43 Application of Safety Grounds Grounds / 4.47 The Equipotential Equipotential Zone / 4.48 Removal of Safety Grounds / 4.49 Control of Safety Grounds Grounds / 4.49 Flash Hazard Calculations and and Approach Approach Distances / 4.51 Introduction / 4.51 Approach Distance Definitions Definitions / 4.51 Determining Shock Hazard Approach Distances / 4.51 Calculating the Flash Hazard Minimum Approach Distance (Flash Protection Protection Boundary) / 4.53 Calculating the Required Level of Arc Protection (Flash Hazard Calculations) / 4.56 Introduction / 4.56 The Lee Method / 4.56 Methods Outlined in NFPA NFPA 70E / 4.58 IEEE Std Std 1584-2002 1584-2002 / 4.59 Software Solutions / 4.60 Required PPE for Crossing the Flash Hazard Boundary / 4.60 A Simplified Approach to the Selection of Protective Clothing / 4.61 Barriers and Warning Signs / 4.61 Illumination / 4.65 Conductive Conductive Clothing and and Materials / 4.66 Confined Work Spaces / 4.66 Tools and Test Test Equipment / 4.67 General / 4.67 Authorized Users / 4.68 Visual Inspections Inspectio ns / 4.68 Electrical Tests Tests / 4.68 Wet and Hazardous Environments / 4.69 Field Marking of Potential Hazards / 4.69 The One-Minute One-Minute Safety Audit / 4.70 References / 4.72
Chapter 5. Grounding and Bonding of Electrical Systems and Equipment Introduction / 5.1 Electric Shock Shock Hazard / 5.1 General Requirements Requirements for Grounding Grounding and Bonding / 5.2 Grounding of Electrical Systems / 5.2 Grounding of Electrical Equipment / 5.8
5.1
CONTENTS
ix
Bonding of Electrically Conductive Conductive Materials and Other Other Equipment / 5.8 Performance of Fault Fault Path / 5.10 Arrangement to Prevent Prevent Objectionable Objectionable Current / 5.10 Alterations to Stop Objectionable Objectionable Current / 5.10 Temporary Currents Not Classified Classified as Objectionable Current / 5.10 Connection of Grounding Grounding and Bonding Bonding Equipment / 5.10 Protection of Ground Ground Clamps and Fittings / 5.11 Clean Surfaces / 5.11 System Grounding / 5.11 Purposes of System Grounding / 5.11 Grounding Service-Supplied Service-Supplied Alternating-Current Alternating-Current Systems Systems / 5.11 Conductors to Be Grounded—AlternatingGrounded—Alternating-Current Current Systems / 5.13 Main Bonding Bonding Jumper Jumper / 5.13 Grounding Electrode System System / 5.13 Grounding Electrode System Resistance / 5.16 Grounding Electrode Conductor Conductor / 5.17 Grounding Conductor Conductor Connection to Electrodes / 5.18 Bonding / 5.20 Equipment Grounding / 5.21 Equipment to Be Grounded / 5.21 Grounding CordCord- and Plug-Connected Plug-Connected Equipment / 5.21 Equipment Grounding Grounding Conductors Conductors / 5.22 Sizing Equipment Equipment Grounding Conductors / 5.23 Use of Grounded Circuit Circuit Conductor for Grounding Grounding Equipment / 5.24 Ferroresonance / 5.27 Summary / 5.28
Chapter 6. Electrical Maintenance Maintenance and Its Relationship to Safety Safety Introduction / 6.1 The Safety-Related Case for Electrical Electrical Maintenance / 6.1 Overview / 6.1 Regulatory / 6.2 Relationship of Improperly Maintained Electrical Equipment to the Hazards of Electricity / 6.2 Maintenance and the Potential Impact on an Electrical Arc-Flash Arc-Flash / 6.2 Hazards Associated with Electrical Electrical Maintenance / 6.4 The Economic Case for Electrical Electrical Maintenance / 6.4 Reliability-Centered Maintenance (RCM) / 6.6 What Is Reliability-Centered Reliability-Centered Maintenance? Maintenance? / 6.6 A Brief History of RCM / 6.6 RCM in the Industrial Industrial and Utility Arena / 6.7 The Primary RCM Principles Principles / 6.7 Failure / 6.9 Maintenance Actions in an RCM Program / 6.9 Impact of RCM on on a Facilities Life Cycle Cycle / 6.10 Conclusion / 6.12 The Eight-Step Maintenance Program / 6.12 Introduction / 6.12 Step 1—Plan / 6.12 Step 2—Inspect / 6.13 Step 3—Clean / 6.13 Step 4—Tighten / 6.14 Step 5—Lubricate / 6.14 Step 6—Test / 6.14 Step 7—Record / 6.15 Step 8—Evaluate / 6.15 Summary / 6.15
6.1
x
CONTENTS
Frequency of Maintenance Maintenance / 6.15 Determining Determini ng Testing Intervals / 6.16 Condition-Based Maintenance (CBM) (CBM) / 6.16 Introduction / 6.16 The Elements of CBM / 6.17 Data Analysis Methods Methods for CBM / 6.17 Maintenance Requirements Requirements for Specific Equipment Equipment and Locations / 6.21 General Maintenance Maintenance Requirements Requirements / 6.21 Substations, Switchgear, Panelboards, Motor Control Centers, and Disconnect Switches / 6.21 Fuse Maintenance Maintenance Requirements Requirements / 6.22 Molded-Case Circuit Breakers / 6.23 Low-Voltage Low-Voltage Power Circuit Breakers / 6.25 Medium-Voltage Medium-Voltage Circuit Breakers / 6.26 Protective Relays / 6.27 Rotating Equipment / 6.30 Portable Electric Tools Tools and Equipment Equipment / 6.30 Personal Safety and Protective Equipment / 6.30 Electrical Safety by Design / 6.31 Introduction / 6.31 Including Safety in Engineering Design Design Criteria / 6.31 Improved Engineering Standards Standards / 6.33 Conclusion / 6.34 References / 6.34
Chapter 7. 7. Regulatory and Legal Safety Requirements and Standards Introduction / 7.1 The Regulatory Regulatory Bodies / 7.1 International Electrotechnical Electrotechnical Commission Commission (IEC) / 7.1 American National Standards Standards Institute (ANSI) (ANSI) / 7.3 Institute of Electrical and Electronics Engineers (IEEE) / 7.5 National Fire Protection Association Associati on (NFPA) (NFPA) / 7.5 American Society for Testing Testing and Materials (ASTM) (ASTM) / 7.6 American Society of Safety Engineers (ASSE) (ASSE) / 7.7 Occupational Safety and Health Health Administration Administration (OSHA) (OSHA) / 7.8 Other Electrical Safety Organizations / 7.15 The National Electrical Safety Safety Code (NESC)—ANSI (NESC)—ANSI C-2 C-2 / 7.16 General Description / 7.16 Industries and and Facilities Covered / 7.16 Technical and Safety Items Covered Covered / 7.16 The National Electrical Code (NEC)—ANSI/NFPA 70 / 7.17 General Description / 7.17 Industries and Facilities Covered Covered / 7.18 Technical and Safety Items Covered Covered / 7.18 Electrical Electri cal Equipment Maintenance—ANSI/NFP Maintenance—ANSI/ NFPA A 70B / 7.18 General Description / 7.18 Industries and Facilities Covered / 7.19 Technical and Safety Items Covered Covered / 7.19 Standard for Electrical Safety in the Workplace—ANSI /NFPA /NFPA 70E / 7.19 General Description / 7.19 Industries and Facilities Covered Covered / 7.20 Technical and Safety Items Covered Covered / 7.21 American Society for Testing and Materials (ASTM) Standards / 7.21
7.1
CONTENTS
xi
Occupational Safety and Health Administration (OSHA) (OSHA) Standards / 7.21 Overview / 7.21 General Industry / 7.24 Construction Industry / 7.25
Chapter 8. Accident Prevention, Accident Investigation, Rescue, and First Aid
8.1
Introduction / 8.1 Accident Prevention / 8.1 Individual Responsibility / 8.1 Installation Safety / 8.2 Power System Studies / 8.4 First Aid / 8.8 General First First Aid / 8.8 Resuscitation (Artificial Respiration) / 8.13 Heart-Lung Resuscitation / 8.13 Automated External External Defibrillator Defibrillator (AED) / 8.15 How an AED Works Works / 8.17 When Should an AED Be Used? / 8.17 How to Use an Automated External Defibrillator Defibrillator / 8.18 What Risks Are Are Associated Associated with Using an Automated External Defibrillator? Defibrillator? / 8.18 Key Points about about Automated Automated External Defibrillators Defibrillators / 8.18 Rescue Techniques / 8.19 General Rescue Procedures Procedures / 8.19 Elevated Rescue / 8.21 Confined-Space Rescue / 8.21 Ground-Level Rescue / 8.35 Accident Investigation Investigation / 8.37 Purpose / 8.37 General Rules / 8.39 Data Gathering / 8.40 Accident Analysis / 8.41
Chapter 9. Medical Medica l Aspects Aspect s of Electrical Trauma Introduction / 9.1 Statistical Survey / 9.1 Nonoccupational Electrical Trauma Trauma / 9.5 Fatality- and Injury-Related Costs / 9.5 Electrical Events / 9.6 Electrocution and Electrical Fatalities / 9.7 Medical Aspects / 9.9 Nonelectrical Effects Effects in Electrical Events / 9.11 Survivor Experience Experien ce / 9.12 Worker Reflexes / 9.12 Triage and Medical Evacuation Evacuation / 9.13 Stabilization and Initial Evaluation Evaluation / 9.14 Medical and Surgical Intervention Intervention / 9.15 Hospitalization Experience / 9.15 Outpatient Care / 9.17 Rehabilitation Focus and and Return to Work Work Planning / 9.17 Reentry to Employment Settings / 9.17 Plateau in Recovery / 9.18 References / 9.19 Further Reading / 9.20
9.1
xii
CONTENTS
Chapter 10. Low-Voltage Low-Voltage Safety Synopsis
10.1
Introduction / 10.1 Low-Voltage Low-Voltage Equipment Equipmen t / 10.1 Extension Cords / 10.2 Electric Electri c Hand Tools / 10.3 Current Transformers Transformers / 10.5 Grounding Low-Voltage Low-Voltage Systems / 10.6 What Is a Ground? Ground? / 10.6 Bonding versus Grounding / 10.6 Voltage Hazards / 10.7 System Grounds / 10.9 Equipment Grounds / 10.11 Ground-Fault Ground-Fault Circuit Interrupters / 10.14 Arc-Fault Arc-Fault Circuit Interrupters / 10.14 Safety Equipment / 10.15 Overview / 10.15 Hard Hats / 10.15 Eye Protection / 10.15 Arc Protection / 10.18 Rubber Insulating Equipment / 10.19 Voltage-Testing oltage- Testing Devices / 10.19 Safety Procedures / 10.21 General / 10.21 Approach Distances / 10.21 Voltage Measurement / 10.21 Locking and Tagging / 10.22 Closing Protective Protective Devices Devices after Operation / 10.22 Electrical Safety around Electronic Circuits / 10.22 The Nature Nature of the the Hazard / 10.22 Special Safety Precautions / 10.23 Stationary Battery Safety / 10.24 Introduction / 10.24 Basic Battery Battery Construction Construction / 10.25 Safety Hazards of Stationary Batteries / 10.26 Battery Safety Safety Procedures Procedures / 10.26 Electrical Hazards of the Home-Based Business / 10.26 Electrical Hazards Hazards in the the Home / 10.28 Working Alone / 10.29 Working with Employees / 10.29 Evaluating Electrical Safety Safety / 10.30 Electrical Safety Safety Checklists Checklists / 10.30 Electrical Inspections Inspections by Professionals Professionals / 10.31
Chapter 11. 11. MediumMedium - and High-Voltage Safety Synopsis Introduction / 11.1 High-Voltage High-Voltage Equipment / 11.1 Current Transformers Transformers / 11.1 Grounding Systems of over 1000 V / 11.3 What Is Is a Ground? / 11.3 Bonding versus versus Grounding Grounding / 11.4 Voltage Hazards / 11.4 System Grounds / 11.5 Equipment Grounds / 11.7
11.1
CONTENTS
xiii
Safety Equipment / 11.8 Overview / 11.8 Hard Hats / 11.8 Eye Protection / 11.8 Arc Protection / 11.9 Rubber Insulating Equipment / 11.9 Voltage-T oltage- Testing Devices / 11.9 Safety Procedures / 11.12 General / 11.12 Approach Distances / 11.12 Voltage Measurement / 11.14 Locking and Tagging / 11.14 Closing Protective Protective Devices Devices after Operation / 11.14
Chapter 12. Human Factors Factors in Electrical Safety Safety
12.1
Introduction / 12.1 Overview / 12.4 Defense in Depth Depth / 12.4 Evolution of Human Factors / 12.5 Visualization / 12.7 Cognitive Ergonomics / 12.9 Summary / 12.13 References / 12.13 Recommended Readings / 12.14
Chapter 13. Safety Management and Organizational Organizational Structure Structure Introduction / 13.1 Changing the the Safety Culture / 13.1 Electrical Safety Program Structure Structure / 13.3 Electrical Safety Program Program Development Development / 13.4 Company Electrical Safety Safety Team Team / 13.4 Company Safety Policy Policy / 13.5 Assessing the Need Need / 13.5 Problems and Solutions Solutions / 13.6 Program Implementation / 13.6 Examples / 13.6 Company Safety Procedures Procedures / 13.9 Results Assessment Assessment / 13.9 Employee Electrical Safety Safety Teams Teams / 13.9 Reason / 13.9 Method / 13.9 Safety Meetings / 13.10 Who Attends / 13.10 What Material Should Be Covered / 13.11 When Meetings Should Be Held / 13.11 Where Meetings Should Be Held / 13.11 How Long Meetings Should Be / 13.12 Evaluation of Safety Meetings / 13.12 Outage Reports / 13.12 Safety Audits / 13.13 Description / 13.13 Purposes / 13.13
13.1
xiv
CONTENTS
Procedure / 13.14 The Audit Team Team / 13.15 Audit Tools / 13.15 Follow-Up / 13.35 Internal versus versus External Audits / 13.35
Chapter 14. Safety Training Methods Met hods and Systems Introduction / 14.1 Safety Training Training Definitions Definitions / 14.1 Training Myths / 14.2 Conclusion / 14.3 Comparison Compariso n of the Four Most Commonly Used Methods of Adult Training / 14.3 Introduction / 14.3 Classroom Presentation / 14.5 Computer-Based Computer-Bas ed Training Training (CBT) and Web-Based Training (WBT) / 14.6 Video Training / 14.8 Conclusion / 14.9 Elements of a Good Training Program Program / 14.9 Element 1: Classroom Classroom Training Training / 14.9 Element 2: On-the-Job On-the-Job Training Training (OJT) / 14.11 Element 3: Self-Training Self-Training / 14.12 Conclusion / 14.12 On-the-Job Training / 14.13 Setup / 14.13 Implementation / 14.14 Evaluation / 14.15 Conclusion / 14.15 Training Consultants and Vendors / 14.16 Canned Programs Programs and Materials / 14.16 Tailored Programs / 14.16 Training Analysis / 14.17 Evaluating Training Vendors and Consultants / 14.17 Conclusion / 14.18 Training Program Program Setup—A Step-by-Step Step-by-Step Method / 14.18 Introduction / 14.18 Background / 14.18 A Plan / 14.21 Analyze / 14.21 Design / 14.23 Develop / 14.24 Implementation / 14.25 Evaluation / 14.25 Modification / 14.26
Glossary G.1 Index I.1
14.1
FOREWORD
Electrical power makes modern life easier. It provides energy for appliances and factory processes that simplify life and industry. Electricity can be manipulated to carry signals that are easy to interpret, and it can be easily converted to other forms of energy. However However,, the hazards associated with electricity can also cause injuries. In most instances, electricity must be converted to another form before it can be used. For example, electrical energy must be converted to thermal energy before it can be used to cook food, heat water, or warm a room. When electrical energy is converted to a more useful form, the conversion process must be a controlled event. event. When controlled, the conversion process is desirable, the result is good, and the process is safe. Normally, a user of electricity does not think about the conversion process. It is not necessary for process operators to think about converting electrical energy into mechanical energy for the rotation of a motor when they push a start button. Electrical workers and electrical manufacturers have provided the necessary electrical equipment to convert the electrical energy safely to make the motor run. Consensus electrical standards provide adequate guidance for manufacturers, engineers, employees, and employers. When workers are trained to understand and follow the guidance provided by consensus standards, operators can push a start button without concern for their safety. However However,, when they do not understand the guidance, workers sometimes create hazard exposures. Electrical hazards exist in many different forms. Direct contact with an energized conductor exposes workers to current flow through their body. Current flowing through body tissue produces heat and damages or destroys the tissue, sometimes resulting in death. An arcing fault is electrical energy that is being converted to another form of energy, such as heat or pressure, by an uncontrolled process. An arcing fault might expose a worker to injury from the thermal hazard or from the effects of the accompanying pressure wave. To avoid injury from an electrical hazard, workers must avoid exposure to the hazard or use adequate protective equipment and safe work practices. The most important safe work practice is to remove all electrical energy and eliminate any chance that the energy might reappear. If the energy cannot reappear, the equipment or circuit is considered to be in an electrically safe work condition. Consensus standards discussed in this book provide guidance about how to establish an electrically safe work condition. Each worker must be trained to recognize how exposure to each electrical hazard might exist and how to avoid that exposure. Workers are exposed to electrical hazards in many different ways, including the following: •
•
Electrical equipment, devices, and components have a normal lifetime. Control devices sometimes wear out and malfunction with age or lack of maintenance. When a failure occurs, a worker is expected to identify the problem, repair the problem, and restore the equipment to normal service. Electrical equipment must be maintained. Although the electrical energy sometimes is removed before a worker begins a maintenance task (best practice), those tasks often are executed executed while the source of electricity is energized.
xv
xvi
•
•
•
FOREWORD
Equipment and circuits sometimes are modified to add new devices or circuits. Shortterm employees might be expected to work in an environment environment that includes exposure to energized electrical circuits and components. Consultant and service employees are frequently exposed to energized electrical equipment and circuits. When a problem exists that causes a process to malfunction, a worker might open a door or remove a cover and expose an energized electrical conductor or component. In many cases, the worker might troubleshoot while the circuit is energized. Components and conductors might be added within a piece of equipment while the equipment or parts of the equipment remain energized. After correcting a problem, workers sometimes create further hazardous conditions by leaving an equipment door ajar, leaving latches open, replacing covers with a minimum number of screws, and removing devices that create holes in a door or cover. cover.
When workers understand that these conditions expose themselves or others to possible injury, they are more likely to avoid the hazard exposure. Training must build and reinforce that understanding. This book provides guidance to help trainers and other workers develop the necessary understanding. Workers must understand the limits of their knowledge and ability. They should not accept and perform a work/task unless they have been trained and have the experience necessary to avoid all hazards, including electrical hazards. When workers are trained to understand electrical hazards and how to avoid them, then they become a valuable asset to the employer. R�� J����, P.E. P.E. (R������), (R������ ), IEEE Fellow and Former NFPA N FPA 70E Technica Technicall Committee Com mittee Chair. Chair.
PREFACE
This fourth edition of the Electrical Electri cal Safety Handbook comes during an avalanche of changes in the world of electrical safety s afety.. Since the third edition was published, the National Fire Protection Association (NFPA) released the 2009 and 2012 editions of the Standard for Electrical Safety in the Workplace (NFPA 70E). Both documents include numerous changes that both add to and further explain the practical aspects of electrical safety. safety. NFPA NFPA 70E has been adopted by a multitude of facilities, companies, and organizations around the world. Labor unions such as the International Brotherhood of Electrical Workers Workers have widely promoted the electrical safety portions of their apprenticeship programs. Colleges and universities such as Murray State University have added electrical safety as part of their environmental environmental safety and health (ES&H) degree programs. Intensive research is ongoing in areas such as the following: •
Electrical shock hazard in systems as low as 30 volts
•
Electrical arc hazards in systems of 208 volts and below
•
•
Field testing and measurement of arc energies—a collaboration between NFPA and the Institute of Electrical and Electronics Engineers Calculation of incident arc energies in dc systems
The many vendors who write and supply the software packages used for performing engineering studies such as arc-flash analysis have frequently updated their software to give the engineering community better and faster tools to perform the necessary calculations. In addition, the U.S. Occupational Safety and Health Administration (OSHA) has revised the 29 CFR 1910 regulation, Electric Power Generation, Transmission, and Distribution, to include the requirements for an arc-flash analysis and associated arc-rated clothing and personal protective equipment. The construction equivalent, 29 CFR 1926, Subpart V, Electric Power Transmission and Distribution, has been changed to be consistent with 1910.269. As part of the revisions of 1910.269 and 1926, Subpart V, OSHA also revised 1910.137 and 1926.97, Electrical Protective Equipment, to include class 00, 500-volt ac gloves. ANSI/IEEE C2, the National Electrical E lectrical Safety Code, in the 2007 edition required an arc-flash analysis and arc-rated clothing and personal protective equipment. This standard has also been revised for 2012 and expands on and clarifies the existing requirements. In 2008, the Canadian Standards Association published CSA Z462-08, Workplace NFPA 70E. Electrical Safety, which is essentially the Canadian version of NFPA The third edition of the Electrical Safety Handbook (ESH) (ESH) has continued to be widely accepted and used throughout the electrical industry. In fact, the authors have noted that many copies of the ESH are appearing on booksellers’ sales lists from all over the world. Because of the nationality of the authors, the ESH has always used North American regulatory standards for the purpose of example and identifying regulatory needs. While we continue to use the U.S. and Canadian regulations as our guideline, we have modified some of the text to be more inclusive. xvii
xviii
PREFACE
Chapters 1, 3, and 4 continue to serve as the central core of the book by presenting the case for electrical safety (Chapter 1), a broad coverage of electrical safety equipment (Chapter 3), and detailed coverage of electrical safety procedures (Chapter 4). In this fourth edition, we have updated and improved each of these chapters. Chapter 1 has been augmented by inclusion of some information on arc-related hazards such as toxic materials and acoustic injuries. Chapter 3 has been generally edited and new information added on such topics as arc-fault circuit interrupters. Finally, Chapter 4 has also been edited and now includes sections on remote operating devices to be used for enhanced safety when operating switchgear. switchgear. Chapter 2 is new to the fourth edition. This new chapter enhances previous editions of the handbook by covering the fundamental physics underlying the various electrical hazards. The material is presented in a much more technical format than Chapter 1 and uses advanced mathematics and citation of high-level research. The authors’ purpose in adding this chapter is not to move away from the practical information provided in all previous editions. Rather, we are presenting some of the more technical data used as the foundation for all electrical safety research—whether theoretical or practical. In making this information available in a public way, we hope that others will add their voices and efforts to the ongoing work in basic research in electrical safety. Chapter 5 provides a detailed and updated overview of the general requirements for grounding and bonding electrical systems and equipment. The fourth edition features many updated, improved diagrams to help clarify the subject of electrical grounding and bonding. Further, the information in the chapter has been edited and rewritten to help with a subject that many find very difficult to understand. As with all of the chapters in this handbook, Chapter 5 is not intended to replace or be a substitute for the requirements of the current NEC or OSHA regulations. Always use the most current standards and regulations when designing, installing, and maintaining the grounding systems within a facility. facility. Chapter 6 has been extensively edited and contains newly written material. In addition to the information first introduced in the third edition, Chapter 6 has been enhanced with three new sections: the effect of maintenance on the arc-flash hazard, more detailed and technical coverage on the value of a condition-based maintenance program, and the importance of designing safety into the workplace. As always, readers of the fourth edition should refer to other references for more detailed information on electrical maintenance. One good source of detailed information is the InterNational Electrical Testing Association (NETA), whose website is http://www.netaworld.org. Chapter 7 updates the third edition coverage of the consensus and mandatory standards and regulations in the workplace. The specific information reprinted from OSHA has been updated to the most recent versions as of the date of this publication. As before, readers should always refer to OSHA publications, available at www.osha.gov, for www.osha.gov, for the most recent information. Chapter 8 has been generally updated. Also, a new section on the use of automated external defibrillators has been added to provide information on these extremely useful and safe-to-use machines. The sections on pole-top rescue and CPR have also been edited and brought up to date. Chapter 9 provides recent injury and fatality statistics and updated medical evaluation and treatment information. Chapters 10 and 11 continue to be a valuable synopsis of low-voltage (Chapter 10) and medium- and high-voltage (Chapter 11) safety. The reader may refer to these chapters for quick coverage of key safety issues in electrical systems. Of course, Chapters 3, 4, and 5 provide detailed information. Of particular interest to some might be the addition of arc-fault circuit interrupters in Chapter 10. Chapter 12 includes additional references to standards addressing human factors considerations, as well as new information about electrical industry resources regarding ergonomics and human performance.
PREFACE
xix
In Chapter 13, in addition to a general edit and some minor error corrections, we have added more detailed information on how to change the so-called electrical safety culture. Electrical safety, like any human activity, has developed its own share of anecdotes, legends, and so-called urban myths. This culture is often based on assumptions that are not valid. Chapter 13 provides some information on how to change that culture. Chapter 14 contains new, in-depth information about how adult learners should be trained. We provide a comparison of the four most common ways of training adults— classroom presentations, computer-based training (CBT), Internet (Web-based) training (WBT), and simple video training. The other sections of the chapter have been edited and clarified in some cases. J��� C�����, P.E. M��� C������-S������������, M.D., M.P.A. D����� K. N������, C.P.E. A� W�������
