Electrical Safety Code Manual

Electrical Safety Code Manual
اسم المؤلف
Kimberley Keller
التاريخ
12 مايو 2024
المشاهدات
133
التقييم
(لا توجد تقييمات)
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Electrical Safety Code Manual
A Plain Language Guide to National Electrical Code, OSHA, and NFPA 70E
Kimberley Keller
Contents
Preface . ix
Acknowledgments . xi
1 Regulatory Agencies and Organizations . 1
The need for standardized code . 2
The national electrical code . 3
National fire protection association . 7
Birth of a code or standard . 8
National electrical safety code 9
American national standards institute 10
A little knowledge goes a long way 14
2 Establishing an Effective Electrical Safety Program . 17
Safety program goals 19
Safety manuals . 21
Elements of a safety handbook 22
Safety meetings . 23
Training and education 28
Emergency response plan . 31
Documentation and record keeping 34
Reliance versus compliance 43
3 Recognizing the Real Dangers of Electricity 45
What is electricity? . 45
Fire hazards 47
OSHA fire protection standards . 47
Blast and flash injuries . 53
Electrocution 57
4 Working on Energized Parts and Equipment . 65
Qualified workers 66Competent person . 70
Unqualified person . 71
Energized work permits 78
Stored energy 84
Types of lockout/tagout 85
Re-energizing protocols 89
5 Electrical System Grounding and Bonding . 91
Terms to know . 92
What is grounding? 93
Ground faults versus short circuits 95
Overcurrent protection devices 96
Grounded versus grounding 97
Artificial earth 112
Bonding 115
Ungrounded systems . 117
6 Safety Grounding Principals . 123
Safety grounds 124
Safety grounding jumpers 128
7 Understanding Arc Flash and Arc Blast Hazards 143
NAPA 70E 146
Determining safe approach distances 149
Arc flash hazard analysis 153
Personal protective equipment 160
Table method of what to wear . 166
8 Specific Requirements of the NESC . 171
Electric supply installations . 172
Communication lines . 176
Overhead power lines 177
Power line safety for electricians 184
9 NEC Standards of Safety 189
Conductor sizing . 190
vi ContentsBranch circuit sizing . 195
Feeder sizing . 199
Feeder and service loads . 204
Overcurrent protection 213
Clearance safety . 219
10 OSHA Regulations Simplified 223
Frequent violation categories 225
Specific compliance 226
Personal protective equipment 228
Eye protection 229
Head protection . 231
A true story 233
Hardhat classifications 233
Footwear . 236
Confined space regulations . 237
Surviving an OSHA inspection . 239
Contesting an OSHA Citation . 246
11 Accident and Injury Prevention and Procedures . 251
Ergonomics, not just for office workers 252
Ergonomic assessment and injury prevention . 255
Ergonomics and hand tools . 258
Stretches 259
Safety DOs and DON’Ts 261
Ladders 264
First aid 266
Bleeding 267
Eye injury . 268
Electrical shock 268
Heart attacks . 273
CPR 274
Accident reporting and investigation 275
Mandatory reporting . 276
12 Safe Work Practices . 283
Safety conscious employer interviews 285
Contents viiPre-employment physical exams . 287
Employee safety concerns 289
Employee safety rights 289
Material safety data sheets . 291
Workers’ compensation facts 295
Employer workers compensation facts . 297
Workers compensation costs 297
Return to work programs 298
Analyzing previous claims 299
The right tools for safety 300
Electrical protective gloves 304
Electrical safety tips . 306
Trenches 307
Code compliant safety 308
R.E.C. safety practices 309
Recognize hazards 309
Evaluate the hazards . 310
Controlling hazards . 311
Appendix . 313
Index . 377
viii ContentsIndex
Note: Page numbers followed by ‘f ’ indicate figures, ‘b’ indicate boxes.
A
Accident and injury prevention
accident reporting and investigation,
275–276, 277f
bleeding, 267–268
cardiopulmonary resuscitation (CPR),
274–275
electrical shock
cardiac arrest, 268–269, 270f
electrocution, 270–271
first aid, 270–271, 272f
rescue operation, 269–270, 271f
ergonomics
carpal tunnel syndrome (CTS), 252–253,
253f
hand tools, 258–259
load lifting training, 255–256, 257f
mechanical wire-puller, 258
musculoskeletal/soft tissue injuries,
254, 256f
overhead work, 257–258
repetitive stress injury (RSI), 252–253,
254, 255f
eye injury, 268, 269f
first aid, 266–267
heart attacks, 273
ladders
duty ratings, 264
fiberglass, 264
stepladder, 265–266, 265f, 266f
usage, 264
mandatory reporting
fast facts, 279, 281f
illness, OSHA, 278
insurance carrier, 279
OSHA form 301, 278, 279f
workers’ compensation, 276–278
safety, do’s and don’ts, 261–264
stretches, 259–260, 260f
AC conductors, 98, 98f
Animal containment areas, 134
Arc-fault circuit interrupter (AFCI)
protection, 196–197, 197f
Arc flash and blast hazards
analysis
bolted fault capacity, 156, 157
breakers, 158
distance, Dc, 156
electrical arc flash extension, 158, 158f
hazard risk categories, 159, 159f
overcurrent protective device, 156, 158
overload, 155–156
short-circuit, 154–155, 155f
time-current coordination curves, 156, 157f
arc faults, 143–144
bolted fault, 143–144
check list, 169f, 170
damage, 144–145, 145f
energized equipment, 170
intense heat, 144–145
NAPA 70E
Article 100, 148–149
Article 110.6, training, 149
factors, 149, 149f
industry standards, flash prevention, 146
NEC, 146
OSHA, 146
warning labels, 147–148, 147f
personal protective equipment (PPE)
arc thermal performance exposure value
(ATPV), 161
calories per centimeter squared
number, 161
energy break open threshold (EBT), 162
fabric weight, 163
flame resistance, 163, 163f
heat attenuation factor (HAF), 164
low-voltage tasks, 165, 166f
protective arc suit and flash helmet,
161, 162f
risk categories, 164, 164f
synthetic materials, 165–166 377Arc flash and blast hazards (Continued)
types, 165, 165f
voltage rating, 164
safest distance
arc-flash boundaries, 151–152
limited approach boundary, 149–150
nominal voltage, energized circuits/parts,
151, 151f
prohibited approach boundary, qualified
workers, 150, 150f
restricted approach boundary, 150
unqualified person, 149–150
Artificial earth
EGC, 112
objectionable current, 114
OSHA grounding requirements
grounding (earthing), 113–114
wiring systems, 112–113
Authority having jurisdiction (AHJ), 4
B
Bolted fault, 143–144
Bonding jumpers
circuit bonding jumper, 116–117
equipment grounding conductors size,
119, 120f
ground fault current path, 115–116
grounding and bonding facts, 122, 122f
installation, 118–119
metal water piping system, 119–120, 121
rebar attachment, 121, 121f
system bonding jumpers, 115, 116f
worst-case scenario approach, 121–122
Branch-circuit rating
branch circuit requirements, 199
equipment fastening, 198–199
maximum load, 197–198, 198f
OCPD, 199
receptacles, 198, 198f
Burst noise, 126
C
Cardiopulmonary resuscitation (CPR), 60,
274–275
Carpal tunnel syndrome (CTS), 252–253, 253f
Circuit breakers, 96, 97f
Combustible dust, 51–52, 51f
Communication circuits, 177
Communication lines, 176–177
Concrete-encased electrodes, 100
Conductors, electrical supply station, 174–175
Constant-voltage generator, 216, 217f
Current transformer (CT), 173–174, 174f
D
Dangers recognition
arc blast and flash injuries
“bolted” fault, 53
electrical burns, 53
factors, 54
hazards, 54–55
high voltage difference, 54
OSHA requirements, 56–57
electrical current, 45–46, 46f
electrocution
accidents, 57
brain damage, 58, 59f
complications, electrocution, 60–61
heart damage, 58–60
protection vs. electrical current, 62
fire hazards, 47
heating effect of current, 46
OSHA fire protection standards
clearance, 48–49
electrical shock prevention, 49, 49b
hazardous locations, 47
insulating material, 48–49
NEC flammable conditions, 49–53
smoking prohibition, 47
space heaters, 48, 48f
De-energizing power, 308
Defibrillation, 60
Degenerative disc disease, 36–37
E
Electrical arc, 143
faults, 53, 143–144, 153–154
flash boundaries, 151–152, 153f
rating, 148
welding, 220–221
Electrical bonding, 92, 115–117
Electrical hazard, 148
Electrically safe work condition, 148
Electrical safety program
basic components, 18–19
corrective surgery, 20–21
documentation and record keeping
fatalities and hospitalizations, 37–38
hazard programs, 38–39
injury and illness recordkeeping,
34–35
OSHA, 34
preexisting conditions, 36–37
pre-job safety briefings, 39–42
work related, 35
elements, safety handbook, 22–23
378 Indexemergency response plan
evacuation, 32–33
potential emergencies, workplace, 32
preparedness, emergency, 33–34
risk management plan, 31–32
warning procedure, 33–34
employee feedback, 18
ligaments damage, 20
reliance vs. compliance, 43
safety manuals, 21–22
safety meetings
Fred the Head, demonstration tools,
25–27, 26f
humor, 28, 30f
interactive approach, 27
safety topic sheets, 28, 29f
safety trainings, 23–25
workers involvement, 27
torn anterior cruciate ligament, 20, 21f
training and education
CPR and first aid training, 28
physical examination, workers, 28, 28b
respirators, 28
training schedule, 28–31
voluntary participation/enrollment, 31
work-related injuries, 17–18, 19
Electrical shock, 87–88, 88f
cardiac arrest, 268–269, 270f
effects, 62, 63f
electrocution, 270–271
first aid, 270–271, 272f
rescue operation, 269–270, 271f
Electrical system
artificial earth
objectionable current, 114
OSHA grounding requirements, 112–113
bonding, 115–117
ground faults vs. short circuits, 95–96
grounding, 93–95
basic reasons, 93–94
conductor, 94
electrical circuits-earth connection,
93, 94f
electrode conductors, 101–102
electrodes, 98–100
equipment grounding, 106–109
fault current, 93
high voltage systems, 110–111
National Electrical Code, 94–95
neutral conductors, 109–110
overcurrent protection devices (OCPD),
96–97
ungrounded systems, 117–122
Electron collisions, 46
Electronic noise, 126
Energized work equipment, 308
competent person
authority, eliminate hazards, 70, 71
hazards identification, 70, 71f
job foremen, 71
complex lockout/tagout, 85–87
energized work permits
authorized work, 80
job briefing, communication, 80
troubleshooting, 78
work conditions and potential hazards,
79–80
energy storage, 84
life safety, 87–89
qualified workers
definition, 69
degree courses, electricians, 66–67, 67f
expertise, 66–67
hands-on models, training programs,
68, 68f
safety qualified, 69–70, 70f
tradesmen, certification courses, 67–68
training, 66–67
re-energizing protocols, 89
unqualified person
approach boundaries, 77
de-energization, conductors/equipment,
72, 75
diagnostic work, 75
electrically safe work conditions, 74, 74f
electrical power loss, 75
energized electrical work assessment,
77, 77f
flash protection boundary, 73–74
limited approach boundary, 72–74
multi-wire branch circuits, 76, 76b
NFPA 70E article 100, 71–72
PPE, 76
restricted work boundary, 73, 73f
safe work practices, 76–77
shock hazard analysis, 77
system de-energization, 75–76
Equipment grounding, 134
Equipment grounding conductor (EGC), 92
Equipotential ground
equipotential zone creation, 132
fault current, metal conductors, 131–132
grounding connectors and conductors
connection, 132, 133f
grounding grid, 132–133, 133f
Equipotential plane, 134, 135, 136f
Index 379F
Flash hazard, 148
Flash protection boundary, 148
Flicker noise, 126
1/f noise, 126
G
Grounded conductor, 92, 97–98
Ground fault, 93
Ground-fault current path, 93, 95, 95f, 96, 103
Grounding alternating-current systems
equipment grounding
EGCs, 107–108, 109
types, 106–107
grounded neutral conductors, 109–110
grounding electrode conductor installation,
106
grounding high voltage systems, 110–111
50-1000 V with ground detectors, 106
Grounding electrodes, 98–99, 99f
conductor, 93
creation, grounding path, 102–103
neutral power source-earth connection, 101
safety, 103–105
service-entrance conductors, 102
size, 101, 101f
pipes/conduit, 100
requirements, 99–100
several vehicles, electrical connection, 99
types, 100
Grounding-type receptacles, 125b
Ground potential, 138
Guy insulator, 176–177
H
Hardhat’s design, 232, 232f
Hazards
arc flash/blast
fire injury, 54, 55f
intense heat, 54–55
severe burns, 54–55, 55f
control, 311–312
evaluation, 310–311
recognition, 309–310
High voltage gloves, 304, 305f
I
Imbalance current, 103, 104f
Incident energy, 148
Ischemia, 58
K
Kirchoff’s law, 104
L
Least resistance path, 105, 105f
Limited approach boundary, 148
Lockout/tagout
definition, 80
devices, features and design, 82–83
fatalities and injuries prevention, 80–81
motor-operated valves security, 81–82, 82f
multiple lock device, 80–81, 81f
person-in-charge, 81–82
requirements, 83
safety quiz, 89, 90f
types
complex lockout/tagout, 85–87
life safety, 87–89
usage, 83
M
Mandatory reporting
ergonomic safety fast facts, 279, 281f
illness, OSHA, 278
insurance carrier, 279
OSHA form 301, 278, 279f
workers’ compensation, 276–278
Material safety data sheets (MSDS)
carcinogens, 293
chemical reactivity, 292
exposure limit, chemical compounds, 293
hazardous aspects information, 293, 294f
hazardous chemicals, workplace, 291–292
informational document, products, 292
physical characteristics, 293
Minimum igniting current (MIC) ratio, 50, 51
Musculoskeletal disorders (MSDs), 252–253,
254–255
Musculoskeletal injuries, 12–13, 254, 256f
N
National Electrical Code (NEC)
branch circuit sizing
arc-fault circuit interrupter (AFCI)
protection, 196–197, 197f
circuit rating, 197–199
OCPD, 195
single-pole branch circuit wiring, 195, 195f
small-appliance and laundry circuits,
195–196, 196f
clearance safety
arc welding, 220–221
electrical cabinet, 219
transformers, 220
conductor sizing
ampacity, 190
380 Indexcurrent-carrying conductors, 190, 193f
NEC 310.5, 190, 191f
requirements, 193–194
feeder and service loads
ampacity, 212
vs. branch-circuit loads, 209–210
calculations, 211–212
electric clothes dryer loads, 211
heating/cooling package unit, 207–208
lighting loads, 204–206
office heater loads, 206, 206f
Ohms law diagram, 207, 207f
quick reference electric motor load chart,
207, 208f
service disconnection, 212–213
small appliance and laundry loads, 210–211
feeder sizing
conductor amperage, 200
general-use receptacle, 202–203
grounding conductors, 201
lighting load, 203–204
load calculations, 201
OCPD, 199–200
protection, 200
flammable conditions
airborne environmental conditions, 50
air mixtures, 50–51
Article 501, 52
Article 502, 52
Article 503, Class III locations, 53
Class II, Division 1 location, 52
Class II, Division 2 location, 52–53
combustible dust environments, 51–52
fire prevention, 53
locations classifications, 49–50
overcurrent protection
circuit ampacity, 215, 215f
circuit breakers/fuses, 213–214, 214f
fault current, 213
generators, 216–218
motor circuit, 215, 216f
standard circuit breaker sizes, 214, 215f
transformers, 218
voltage rating, 213–214
National Electrical Safety Code
(NESCW), 9
communication lines, 176–177
electric supply installations
conductors, 174–175
current and voltage transformers,
173–174
surge arresters, 175–176, 176f
grounded bus bars, 172, 173f
overhead power lines
line workers, 182, 183, 183f
power line spans, 178–180, 181f
structural clearance support, 183–184
supply employee safety, 180–182
power line safety, electricians
distance, equipment, 184, 186f
electrocution, 184, 185
energized power lines, 184, 185f
facts, potential hazards, 187–188, 188f
fallen power lines, 185–186, 187f
fiber optic cables, 186–187
safe clearances, 184
National Fire Protection Association (NFPA)
Board of Directors, 8
fire hazards, 47
minimum standards and requirements, 7
professional standard, 8
regulations development, 7
representatives, 8
O
Occupational Safety and Health Association
(OSHA), 10–11, 11f, 38–39
bloodborne pathogens, 14
common workplace hazards, 13
confined space regulations
entry permit, 239
manholes, 237, 237f
“permit-required confined space”/“permit
space”, 237
posters, alert workers, 237, 238f
contestation, citation
authorization, negotiation, 247
OSHA hearing, 247–248, 249f
violation, 246–247
ergonomic injuries, 12–13
eye protection, 229–230, 231f
footwear, 236–237
frequent violation categories, 225–226
guards, 13
hardhat classifications
damaged hardhats, 234, 235f
hardhat manufacture, 234, 235f
three industrial classes, 233–234
head protection, 231–232
inspections, 239–246, 290, 291f
employees complaints and reports,
239–240, 241
inspection planning, 241–242
job supervisor, representative, 242–243, 244f
nightmare, standard violation, 244–246
opening meeting, 240
Index 381Occupational Safety and Health Association
(OSHA) (Continued)
OSHA health and safety poster, 242, 243f
trades onsite checking, 240
warrant, site access, 241
mission, 11
MOD rates, 12, 12f
oversees regulations, 11
permissible exposure limits (PEL), 13
personal protective equipment, 228–229
portable ground fault circuit interrupters,
224–225, 225f
private company representatives, 11
regulations, 14
requirements, employers
alerting techniques, 56
“appropriate” precautions, 57
descriptive markings, 56
equipment, warning signs, 56, 56f
specific compliance
AC circuits, 228
grounded conductor, 226–227
power and communication supply lines,
228
receptacle, 226–227
standards, 12–13
statistics approach, 290–291
trenches and excavations, 14
Voluntary Protection Program (VPP), 12
Overcurrent protection
circuit ampacity, 215, 215f
circuit breakers/fuses, 213–214, 214f
fault current, 213
generators, 216–218
motor circuit, 215, 216f
standard circuit breaker sizes, 214, 215f
transformers, 218
voltage rating, 213–214
Overcurrent protection devices (OCPD),
96–97, 108
Overhead power lines
“collinear construction”, 178
conductor, 177–178
line workers, 182, 183, 183f
non-current carrying parts, 177–178
pole separation, 178, 179f
power line spans
clearances, line sag and separation,
180, 181f
conductors sag, 178–179, 180
“ruling span”, 179
structural clearance support, 183–184
supply employee safety, 180–182
P
Personal protective equipment (PPE), 228–229
arc thermal performance exposure value
(ATPV), 161
calories per centimeter squared number, 161
energized work equipment, 76
energy break open threshold (EBT), 162
fabric weight, 163
flame resistance, 163, 163f
heat attenuation factor (HAF), 164
low-voltage tasks, 165, 166f
protective arc suit and flash helmet,
161, 162f
risk categories, 164, 164f
safe work practices, 287–288, 289
synthetic materials, 165–166
types, 165, 165f
voltage rating, 164
Potential transformer (PT) see Voltage
transformer (VT)
Power line safety, electricians
distance, equipment, 184, 186f
electrocution, 184, 185
energized power lines, 184, 185f
facts, potential hazards, 187–188, 188f
fallen power lines, 185–186, 187f
fiber optic cables, 186–187
safe clearances, 184
Pre-job safety briefings
extension cords, 41, 42f
hazards identification, 39
job assessment, 41
pre-printed handouts, work safety, 41, 42f
safe conditions, power lines, 41, 43f
standardization, 40, 40f
working performance, 39
R
Regulatory agencies and organizations
American National Standards Institute
(ANSI)
accreditation, 10–11
mission, 10
nonprofit organization, 10
open standards, 10–11
committees and panels, 8
construction methods, 1
installation techniques, 1–2
National Electrical Code (NEC)
article 90, 4
code panels, 4
conductors and equipment installation, 3
382 Indexdefinitions, 3, 3f
design specification, instruction manual,
4, 5f
Handbook, 6, 6f
safeguarding people and property,
hazards, 4
National Electrical Safety Code (NESCW), 9
National Fire Protection Association
(NFPA)
Board of Directors, 8
minimum standards and requirements, 7
professional standard, 8
regulations development, 7
representatives, 8
negligence, 2–3
Occupational Safety and Health Association
(OSHA)
bloodborne pathogens, 14
common workplace hazards, 13
ergonomic injuries, 12–13
guards, 13
mission, 11
MOD rates, 12, 12f
oversees regulations, 11
permissible exposure limits (PEL), 13
private company representatives, 11
regulations, 14
standards, 12–13
trenches and excavations, 14
Voluntary Protection Program
(VPP), 12
three central electrical safety texts, 14, 15f
Reinforcing rod, 134, 136b
Repetitive stress injury (RSI), 252–253,
254, 255f
Respiratory protection program, 38–39
S
Safety grounding
isolated ground, 125–126
jumpers
drain, static charge, 128
equipotential ground, 131–133
equipotential planes and animal
confinement, 134–135
installation, 129–130
protection vs. varied voltage, 136–137
removing safety grounds, 131, 132f
resistance, 129–130, 130f
standard AC wiring diagram, 130–131,
131f
three-wire power distribution system,
130–131
touch and step potential, 137–140
ultimate short circuit potential, 128, 129f
requirements and mechanics, 124–125
single-point grounding, 126–127, 127f
three-phase distribution ground, 127–128
three-prong adapters, 124, 125f
Safety manual mission statement, 22, 22f
Safe work practices
claims analysis, 299–300, 300f, 301f
code compliant safety, 308
contractors, 284
electrical protective gloves, 304–306
employee safety
concerns, 289
rights, 289–291
hazards
control, 311–312
evaluation, 310–311
recognition, 309–310
material safety data sheets (MSDS)
carcinogens, 293
chemical reactivity, 292
exposure limit, chemical compounds, 293
hazardous aspects information, 293, 294f
hazardous chemicals, workplace, 291–292
informational document, products, 292
physical characteristics, 293
pre-employment physical exams
physical ability tests, 287–288, 288f
PPE, 287–288, 289
safety quiz, 289
recognize, evaluate, control (REC), 309
return to work programs, 298–299
right tools
high-voltage tools, insulation, 303
insulated hot sticks, 303, 304, 304f
meter, 301–302, 303
multimeter, 302, 302f
saw blade, material, 300–301
safety conscious employer interviews
employee’s physical ability, 285–286
interview, 287
safety tips, 306–307
trenches, 307–308
workers compensation costs, 297–298
workers’ compensation facts
average weekly wage (AWW), 296–297
employer, 297
impairment rating, 295–296
insurance company, 295
temporary total disability (TTD), 295
workplace injury, 295, 296f
Shot noise, 126
Index 383Single-point grounding system, 126–127, 127f
Soft tissue injuries, 254, 256f
Solidly grounded neutral system, 110, 110f
Standardized code, 2–3
Step voltage, 134
Stray voltage, 135, 136–137
Surge arresters, 175–176, 176f
T
Thermal burns, 60–61
Thermal noise, 126
Three-wire DC generators, 217
Tingle/extraneous voltage see Stray voltage
Touch and step potential
definition, 137
engineering analysis, power system, 138–140
ground fault, power line, 137
ground potential gradient, 138
protection, employees, 140, 141f
touch voltage, 138, 139f
voltage curve, 138
Touch voltage, 135
Transformer overcurrent protection methods,
218, 219f
Tripped circuit breakers, 310
Two-wire DC generator, 216–217
U
Ungrounded systems
bonding jumpers types, 118–122
bonding termination locations, 118
electrical equipment bonding, 117
grounding and bonding facts, 122f
non-current carrying metal parts, 118
V
Ventricular fibrillation, 58–59
Voltage ramp, 135, 137
Voltage transformer (VT), 173–174, 175f
W
Water piping system, 102
Wire mesh, 135
Workers compensation
costs, 297–298
facts
average weekly wage (AWW), 296–297
employer, 297
impairment rating, 295–296
insurance company, 295
temporary total disability (TTD), 295
workplace injury, 295, 296f
384 Index

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