TPC TRAINCO
Real World Training...for Real World Needs
Principles of LOTO ExecuƟon
VeriĮcaƟon of an Electrically Safe Work CondiƟon
(1) Determine all possible sources of electrical supply to the speciĮc equipment.
Check applicable up-to-date drawings, diagrams, and idenƟĮcaƟon tags.
(2) AŌer properly interrupƟng the load current, open the disconnecƟng device(s) for
each source.
(3) Wherever possible, visually verify that all blades of the disconnected devices
are fully open or that draw-out type circuit breakers are withdrawn to the fully
disconnected posiƟon.
1. Employee Involvement
2. Training
3. Retraining
4. Training DocumentaƟon
5. Plan
6. Control of Energy
7. IdenƟĮcaƟon
8. Voltage
9. CoordinaƟon
Review Procedures for Hazardous
Energy Control
1. Simple lockout/tagout procedure
2. Complex lockout/tagout procedure
3. CoordinaƟon of procedures
(4) Apply lockout/tagout devices in accordance with a documented and
established policy.
(5) Use an adequately rated test instrument to test each phase conductor or circuit
part to verify it is de-energized. Test each phase conductor or circuit part both phaseto-phase and phase-to-ground. Before and aŌer each test, determine that the test
instrument is operaƟng saƟsfactorily, through veriĮcaƟon on a known voltage source.
(6) Where the possibility of induced voltages or stored electrical energy exists,
ground the phase conductors or circuit parts before touching them. Where it could
be reasonably anƟcipated that the conductors or circuit parts being de-energized
could contact other exposed energized conductors or circuit parts, apply ground
connecƟng devices rated for the available fault duty.
Electronic Sensing
& Shunt Trip
Test
Resistor bypasses ≥6 mA of
current for test
CB
Reset
Note: Grounding
conductor not required
Receptacle
& Plug
1. Lock applicaƟon
2. LOTO device
3. Lockout device
4. Tagout device
5. Electrical circuit Interlocks
6. Control devices
Procedures – Equipment
1. Planning is required in procedures
a. LocaƟng sources
b. Exposed persons
c. Person in charge
d. Simple lockout/tagout
e. Complex LOTO
2. Elements of Control must be IdenƟĮed
a. De-energizing of equipment
b. Release of stored energy
c. DisconnecƟng means
d. ResponsibiliƟes
e. VeriĮcaƟon procedures
f. TesƟng requirements
g. Grounding
h. ShiŌ change
i. CoordinaƟon
j. Accountability of personnel
k. Lockout/Tagout applicaƟon
l. Removal of Lockout/Tagout Devices
(Ground-Fault Circuit Interrupter (GFCI). A device intended for the protecƟon of
personnel that funcƟons to de energize a circuit or porƟon thereof within an established
period of Ɵme when a current to ground exceeds the values established for a Class A
device. [NEC® ArƟcle 100]
InformaƟonal Note: Class A ground-fault circuit-interrupters trip when the current to
ground is 6 mA or higher and do not trip when the current to ground is less than 4 mA.
For further informaƟon see ANSI/UL 943 Standard for Ground-Fault.
NFPA 70E® ArƟcle 110.4(C) Ground-Fault Circuit-Interrupter (GFCI) ProtecƟon.
(2) Maintenance and ConstrucƟon. GFCI protecƟon shall be provided where an
employee is operaƟng or using cord- and plug-connected tools related to maintenance
and construcƟon acƟvity supplied by 125-volt, 15-, 20-, or 30-ampere circuits. Where
employees operate or use equipment supplied by greater than 125-volt, 15-, 20-, or
30-ampere circuits, GFCI protecƟon or an assured equipment grounding conductor
program shall be implemented.
L2
Kirchoff’s law
requires these values
must be equal
Equipment
(1) General. Employees shall be provided with ground fault circuit-interrupter (GFCI)
protecƟon where required by applicable state, federal, or local codes and standards.
Listed cord sets or devices incorporaƟng listed GFCI protecƟon for personnel idenƟĮed for
portable use shall be permiƩed.
L1
Current
Transformer
Responsibility for LOTO
1. Employer establishes procedures and
provides training on these procedures
2. Two forms of control permiƩed
a. Simple LOTO
b. Complex LOTO
3. Audit procedures (Annually)
Coil inside
portable tool
Trips at ≥6 mA difference
between L1 and L2 in less
than 0.1 seconds
(3) Outdoors. GFCI protecƟon shall be provided when an employee is outdoors and
operaƟng or using cord- and plug-connected equipment supplied by 125-volt, 15-, 20-,
or 30-ampere circuits. Where employees working outdoors operate or use equipment
supplied by greater than 125-volt, 15-, 20-, or 30-ampere circuits, GFCI protecƟon or an
assured equipment grounding conductor program shall be implemented.
NFPA 70E® ArƟcle 110.4(D) Ground-Fault Circuit-Interrupter ProtecƟon Devices. GFCI
protecƟon devices shall be tested in accordance with the manufacturer’s instrucƟons.
For more informaƟon see OSHA Sub part S® or NFPA 70E®
1. Warning
Item 1 complies with NEC® ArƟcle 110.16 and NFPA 70E® ArƟcle 130.7(E)(1) and warns
people of the possible arc Ňash and shock hazard as well as the need to use proper PPE.
2. Arc Ňash protecƟon boundary
This is the calculated distance from a possible arc source where the incident energy
drops to 1.2 calories per square cenƟmeter and is widely recognized as the minimum
energy required to produce the onset of a second-degree burn. People working within
this boundary when an arc Ňash hazard exists must wear appropriate Ňame-resistant
clothing and PPE.
3. Incident energy
The incident energy is based on detailed calculaƟons at a speciĮc working distance
from the perspecƟve arc source. The arc raƟng of the Ňame-resistant clothing and PPE
must be equal to or greater than this value.
4. Table Method VS CalculaƟon Method
System
Voltage Range,
Ø to Ø1
Limited Approach Boundary2
Exposed
Movable
Conductor3
Exposed Fixed
Circuit Part
Restricted
Approach
Boundary2
< 50 Volts
not speciĮed
not speciĮed
50 V - 150 V
10' - 0"
3' - 6"
not speciĮed
avoid contact
> 151 V - 750 V
10' - 0"
3' - 6"
1' - 0"
> 751 V - 15 kV
10' - 0"
5' - 0"
2' - 2"
> 15.1 kV - 36 kV
10' - 0"
6' - 0"
2' - 7"
> 36.1 kV - 46 kV
10' - 0"
8' - 0"
2' - 9"
Available incident energy and the corresponding working distance, or the arc Ňash PPE
category in Table 130.7(C)(15)(A)(b) or Table 130.7(C)(15)(B) for the equipment, but not both.
5. Shock hazard
This is the voltage at which the equipment operates at.
6. Limited approach boundary
DeĮnes the closest approach to an exposed electrical hazard, (conductor, component,
etc.), for non-qualiĮed personnel, unless escorted by a qualiĮed worker. Determines
the minimum safe distance for the placement of barricades for shock protecƟon if this
distance is greater than the arc Ňash boundary. If the qualiĮed electrical workers are
unable or unwilling to provide escort for unqualiĮed workers, the unqualiĮed worker
may not enter the limited approach boundary.
7. Restricted approach boundary
QualiĮed electrical workers only. All required PPE appropriate for the hazards shall be
worn. The worker is now working near the exposed hazard. The worker must have an
approved plan for the work they are to perform. They may cross the restricted boundary
only to the extent that is necessary to perform their work.
8. Date of study/label
NFPA 70E® ArƟcle 130.5 requires that the arc Ňash hazard analysis either be updated
when major modiĮcaƟons or renovaƟons take place, or else it should be reviewed
periodically at most every Įve years.
9. Where the panel is fed from
Since much of the informaƟon from the arc Ňash study is equipment and locaƟonspeciĮc, an equipment idenƟĮcaƟon should be listed.
10. Study performed by
This should be listed in case you have a quesƟon about the study.
Nominal
PotenƟal
Diīerence
Limited Approach Boundary
Exposed
Movable
Conductor2
Exposed Fixed
Circuit Part
Restricted
Approach
Boundary2
< 100 Volts
not speciĮed
not speciĮed
not speciĮed
100 V - 300 V
10' - 0"
3' - 6"
avoid contact
> 301 V - 1 kV
10' - 0"
3' - 6"
1' - 0"
> 1.1 kV - 5 kV
10' - 0"
5' - 0"
1' - 5"
> 5.1 kV - 15 kV
10' - 0"
5' - 0"
2' - 2"
> 15.1 kV - 45 kV
10' - 0"
8' - 0"
2' - 9"
> 45.1 kV - 75 kV
10' - 0"
8' - 0"
3' - 2"
PPE Category
1
Arc Flash Hazard - A dangerous condiƟon associated with the possible release of
energy caused by an electric arc.
Personal ProtecƟon Equipment (PPE)
Arc-Rated Clothing, Minimum Arc RaƟng of 4 cal/cm² (see Note 1)
Arc-rated long-sleeve shirt and pants or arc-rated coverall
Arc-rated face shield (see Note 2) or arc Ňash suit hood
Arc-rated jacket, parka, rainwear, or hard hat liner (AN)
ProtecƟve Equipment - Hard hat, Safety glasses or safety goggles (SR),
Hearing protecƟon (ear canal inserts), Heavy duty leather gloves (see
Note 3), Leather footwear (AN)
2
3
Arc-Rated Clothing, Minimum Arc RaƟng of 8 cal/cm² (see Note 1)
Arc-rated long-sleeve shirt and pants or arc-rated coverall
Arc-rated Ňash suit hood or arc-rated face shield (see Note 2)
and arc-rated balaclava
Arc-rated jacket, parka, rainwear, or hard hat liner (AN)
Arc RaƟng - The value aƩributed to materials that describes their performance to
exposure to an electrical arc discharge. The arc raƟng is expressed in cal/cm2 and is
derived from the determined value of the arc thermal performance value (ATPV) or
energy of break-open threshold (EBT) (should a material system exhibit a break-open
response below the ATPV value). Arc raƟng is reported as either ATPV or EBT,
whichever is the lower value.
Balaclava (Sock Hood) - An arc-rated hood that protects the neck and head except for
the facial area of the eyes and nose.
ProtecƟve Equipment - Hard hat, Safety glasses or safety goggles (SR),
Hearing protecƟon (ear canal inserts), Heavy duty leather gloves (see
Note 3), Leather footwear
Boundary, Limited Approach - An approach limit at a distance from an exposed
energized electrical conductor or circuit part within which a shock hazard exists.
Arc-Rated Clothing Selected so that the System Arc RaƟng Meets
the Required Minimum Arc RaƟng of 25 cal/cm² (see Note 1)
Arc-rated long-sleeve shirt (AR)
Arc-rated pants (AR)
Arc-rated coverall (AR)
Arc-rated Ňash suit jacket (AR)
Arc-rated Ňash suit pants (AR)
Arc-rated Ňash suit hood
Arc-rated gloves (see Note 1)
Arc-rated jacket, parka, rainwear, or hard hat liner (AN)
Boundary, Restricted Approach - An approach limit at a distance from an exposed
energized electrical conductor or circuit part within which there is an increased
likelihood of electric shock, due to electrical arc-over combined with inadvertent
movement, for personnel working in close proximity to the energized electrical
conductor or circuit part.
ProtecƟve Equipment - Hard hat, Safety glasses or safety goggles (SR),
Hearing protecƟon (ear canal inserts), Leather footwear (AN)
4
Arc Flash Suit - A complete arc-rated clothing and equipment system that covers the
enƟre body, except for the hands and feet.
Current-LimiƟng Over - Current ProtecƟve Device - A device that, when interrupƟng
currents in its current-limiƟng range, reduces the current Ňowing in the faulted circuit
to a magnitude substanƟally less than that obtainable in the same circuit if the device
were replaced with a solid conductor having comparable impedance.
De-energized - Free from any electrical connecƟon to a source of potenƟal diīerence and
from electrical charge; not having a potenƟal diīerent from that of the earth.
Arc-Rated Clothing Selected so that the System Arc RaƟng Meets
the Required Minimum Arc RaƟng of 40 cal/cm² (see Note 1)
Arc-rated long-sleeve shirt and pants or arc-rated coverall
Arc-rated Ňash suit hood
Arc-rated jacket, parka, rainwear, or hard hat liner (AN)
Electrically Safe Work CondiƟon - A state in which an electrical conductor or circuit
part has been disconnected from energized parts, locked/tagged in accordance with
established standards, tested to ensure the absence of voltage, and grounded if
determined necessary.
ProtecƟve Equipment - Hard hat, Safety glasses or safety goggles (SR),
Hearing protecƟon (ear canal inserts), Leather footwear (AN)
Ground Fault - An unintenƟonal, electrically conducƟng connecƟon between an
ungrounded conductor of an electrical circuit and the normally non–current-carrying
conductors, metallic enclosures, metallic raceways, metallic equipment, or earth.
Note: AN: as needed (opƟonal). AR: as required. SR: selecƟon required
1. Arc raƟng is deĮned in ArƟcle 100
2. Face shields are to have wrap-around guarding to protect not only the face but also the
forehead, ears, and neck, or alternaƟvely, and are-rated arc Ňash suit hood is required
to be worn.
3. If rubber insulaƟng gloves with leather protectors are used, addiƟonal leather or arcrated gloves are not required. The combinaƟon of rubber insulaƟng gloves with leather
protectors saƟsĮes the arc Ňash protectors required.
NFPA 70E® ANNEX H - SimpliĮed, Two-Category, Arc RaƟng Clothing System
Incident Energy - The amount of thermal energy impressed on a surface, a certain
distance from the source, generated during an electrical arc event. Incident energy is
typically expressed in calories per square cenƟmeter (cal/cm2).
Incident Energy Analysis - A component of an arc Ňash risk assessment used to predict
the incident energy of an arc Ňash for a speciĮed set of condiƟons.
InterrupƟng RaƟng - The highest current at rated voltage that a device is idenƟĮed to
interrupt under standard test condiƟons.
Clothing
PPE
Categories
Arc Rated long sleeve shirt with Arc Rated pants or Arc Rated coveralls
(min. ATPV of 8 cal/cm²)
1-2
Over-current - Any current in excess of the rated current of equipment or the ampacity
of a conductor. It may result from overload, short circuit, or ground fault.
Arc Flash Suit - A total clothing system consisƟng of Arc Rated shirt
& pants and/or Arc Rated coveralls and/or Arc Flash coat and pants.
Total arc raƟng of 40 cal/cm²
3-4
QualiĮed Person - One who has demonstrated skills and knowledge related to the
construcƟon and operaƟon of electrical equipment and installaƟons and has received
safety training to idenƟfy and avoid the hazards involved.
ProtecƟve Rubber Glove and Sleeve InformaƟon Chart
Rubber
ClassiĮcaƟon
Class 00
Class 0
Class 1
Class 2
Class 3
Class 4
Label
Color
Max Use Voltage
(AC)
Beige
500
Red
1,000
White
7,500
Yellow
17,000
Green
26,500
Orange
36,000
Type I (Non-ozone-resistant)
Proof Test Voltage
(DC)
(AC)
750
2,500
1,500
5,000
11,250
10,000
25,500
20,000
39,750
30,000
54,000
40,000
Type II (Ozone-resistant)
(DC)
10,000
20,000
40,000
50,000
60,000
70,000
Risk - A combinaƟon of the likelihood of occurrence of injury or damage to health and
the severity of injury or damage to health that results from a hazard.
Risk Assessment - An overall process that idenƟĮes hazards, esƟmates the
potenƟal severity or damage to health, esƟmates the likelihood of occurrence of injury
or damage to health, and determines if protecƟve measures are required.
Shock Hazard - A dangerous condiƟon associated with the possible release of energy
caused by contact or approach to energized electrical conductors or circuit parts.
Leather protectors must meet ASTM speciĮcaƟon F696® and should always be worn over
rubber insulaƟng gloves to prevent mechanical damage to the rubber gloves - except for
those condiƟons detailed in ASTM F496®.
Short-Circuit Current RaƟng - The prospecƟve symmetrical fault current at a nominal
voltage to which an apparatus or system is able to be connected without sustaining
damage exceeding deĮned acceptance criteria.
Hard Hat
ClassiĮcaƟon
Voltage
RaƟng
Class E
Class G
Class C
20,000 V
2,200 V
0
Working On (energized electrical conductors or circuit parts) - IntenƟonally
coming in contact with energized electrical conductors or circuit parts with the hands,
feet, or other body parts, with tools, probes, or with test equipment, regardless of the
personal protecƟve equipment a person is wearing. There are two categories of
“working on”: DiagnosƟc (tesƟng) is taking readings or measurements of electrical
equipment with approved test equipment that does not require making any physical
change to the equipment; repair is any physical alteraƟon of electrical equipment.
(such as making or Ɵghtening connecƟons, removing or replacing components, etc.)
Basic DescripƟon
Excellent protecƟon for electrical workers.
Good impact protecƟon but limited voltage protecƟon
Only protect workers from bumping against Įxed objects
Type 1 hats are designed to protect from objects that might fall from above or into
which you might collide.
Type 2 hats protect from both verƟcal and horizontal threats.
Task
Reading a panel meter while
operaƟng a meter switch
Equipment CondiƟon*
Arc Flash PPE Required
Yes
Any
X
The equipment is
properly installed
The equipment is not
properly installed
X
X
The equipment is
properly maintained
The equipment is not
properly maintained
Normal operaƟon of a circuit
breaker (CB), switch, contactor,
or starter
X
X
All equipment doors are
closed and secured
All equipment doors are
not closed and secured
X
X
All equipment covers are
in place and secured
All equipment covers are
not in place and secured
X
X
There is no evidence of
impending failure
There is evidence of
impending failure
No
X
X
Arc Flash PPE Required
Task
Equipment CondiƟon*
Work on control circuits with
exposed energized electrical
conductors and circuit parts, 120
volts or below without any other
exposed energized equipment
over 120V including opening of
hinged covers to gain access
Any
Work on control circuits with
exposed energized electrical
conductors and circuit parts
greater than 120V
Any
X
InserƟon or removal (racking) of
CBs or starters from cubicles doors
open or closed
Any
X
InserƟon or removal of plug-in
devices into or from busways
Any
X
Work on exposed energized
electrical conductors and circuit
parts of equipment directly
supplied by a panelboard or
motor control center
Any
X
InserƟon and removal of revenue
meters (KW-hour, at primary
voltage and current)
Any
X
Opening Voltage Transformer
or control power transformer
compartments
Any
X
Yes
No
X
For AC systems:
Work on energized electrical
conductors and circuit parts,
including voltage tesƟng
Any
X
For DC systems:
Work on energized electrical
conductors and circuit parts of
series-connected baƩery cells,
including voltage tesƟng
Any
X
Task
1
X
Panelboards or other equipment rated 240V and below
Parameters Maximum of 25KA short circuit current available;
maximum of 0.03 sec (2 cycles) fault clearing Ɵme; work
distance 455mm (18in)
485mm
(19in)
Panelboards or other equipment rated >240V and up to 600V
Parameters Maximum of 25KA short circuit current available;
maximum of 0.03 sec (2 cycles) fault clearing Ɵme; work
distance 455mm (18in)
2
900mm
(3Ō)
600V class motor control centers (MCC)
Parameters Maximum of 65KA short circuit current available;
maximum of 0.03 sec (2 cycles) fault clearing Ɵme; work
distance 455mm (18in)
2
1.5m
(5Ō)
600V class motor control centers (MCC)
Parameters Maximum of 42KA short circuit current available;
maximum of 0.33 sec (20 cycles) fault clearing Ɵme; work
distance 455mm (18in)
4
4.3m
(14Ō)
600V class switchgear (with power circuit breakers
or fused switches) and 600V class switchboards
Parameters Maximum of 35KA short circuit current available;
maximum of 0.5 sec (30 cycles) fault clearing Ɵme; work
distance 455mm (18in)
4
6m
(20Ō)
Other 600V class (277 through 600V, nominal) equipment
Parameters Maximum of 65KA short circuit current available;
maximum of 0.03 sec (2 cycles) fault clearing Ɵme; work
distance 455mm (18in)
2
1.5m
(5Ō)
4
X
NEMA E2 (fused contactor) motor starters, 2.3KV trough 7.2KV
Parameters Maximum of 35KA short circuit current available;
maximum of 0.24 sec (15 cycles) fault clearing Ɵme; work
distance 910mm (36in)
12m
(40Ō)
4
X
Metal-clad switchgear, 1KV trough 15KV
Parameters Maximum of 35KA short-circuits current available;
maximum of up to 0.24 sec (15 cycles) fault clearing Ɵme;
working distance 910mm (36in)
12m
(40Ō)
X
Arc-resistant switchgear Type 1 or 2 [for clearing Ɵmes of < 0.5 sec
(30 cycles) with a perspecƟve fault current not to exceed the arc
N/A
resistant raƟng of the equipment], and metal-enclosed interrupter
(doors closed)
switchgear, fused or unfused of arc-resistant-type construcƟon,
tested in accordance with IEEE C37.20.7, 1 kV through 15 kV
Removal or installaƟon of CB
or switches
Any
The equipment is
properly installed
The equipment is not
properly installed
X
X
The equipment is
properly maintained
Removal or installaƟon of covers
for equipment such as wireways,
juncƟon boxes and cable trays
that does not expose bare
energized electrical conductors
and circuits parts
The equipment is not
properly maintained
X
X
All equipment doors are
closed and secured
All equipment doors are
not closed and secured
X
X
All equipment covers are
in place and secured
All equipment covers are
not in place and secured
X
X
There is no evidence of
impending failure
There is evidence of
impending failure
Removal of bolted covers (to
expose bare energized electrical
conductors and circuit parts) For DC
systems this includes bolted covers,
such as baƩery terminal covers
Any
Opening hinged door(s) or cover(s)
(to expose bare energized electrical
conductors and circuit parts)
Any
Perform infrared thermography
and other non-contact inspecƟons
outside the restricted approach
boundary. This acƟvity does not
include opening of doors or covers
X
Parameters: Maximum of 35 kA short-circuit current available;
maximum of up to 0.24 sec (15 cycles) fault clearing Ɵme;
working distance 910 mm (36 in.)
Any
X
Arc Flash PPE Arc Flash
Category
Boundary
4
(doors open)
N/A
(doors
closed)
12m
(40Ō)
Fuse Size or
Maximum
Minimum Size
Maximum
Inverse Time
Non-ConƟnuous
of Wire
ConƟnuous Load
Breaker
Load
Wire sizes are based on 60 degree rated terminals
See NEC® ArƟcles 110.14(C)(1)(a)&(b), 210.20(A) and Table 310.15(B)(16)
Current
SensaƟon
0.3 to 3 milliamps
Tingling
3 to 10 milliamps
Muscle contracƟon and pain
10 to 40 milliamps
“Let-go” threshold
15
14 awg
12 amps
15 amps
30 to 75 milliamps
Respiratory paralysis
20
12 awg
16 amps
20 amps
100 to 200 milliamps
Ventricular ĮbrillaƟon
25
10 awg
20 amps
25 amps
200 to 500 milliamps
Heart clamps Ɵght
30
10 awg
24 amps
30 amps
1.5 amps
Tissue and organs start to burn
35
8 awg
28 amps
35 amps
40
8 awg
32 amps
40 amps
45
6 awg
36 amps
45 amps
50
6 awg
40 amps
50 amps
60
4 awg
48 amps
60 amps
70
4 awg
56 amps
70 amps
110°
6.0 Hours
Cell breakdown begins
80
3 awg
64 amps
80 amps
158°
1.0 second
Total cell destrucƟon
Skin
Temperature
Time to Reach
Temperature
Damage Caused
90
2 awg
72 amps
90 amps
176°
0.1 second
Second degree burn
100
1 awg
80 amps
100 amps
200°
0.1 second
Third degree burn
110
1 awg
88 amps
110 amps
125
1/0 awg
100 amps
125 amps
150
3/0 awg
120 amps
150 amps
200
250 kcmil
160 amps
200 amps
Wire size must be an ampacity equal to or greater than the ampacity of the breaker
or fuse. Example: A #12 awg wire cannot be installed to a 30 amp Breaker*
NEC® ArƟcle 430 & 440 are the excepƟon to this rule
A conƟnuous load is any load that can run for 3 hours or more
When energized work is permiƩed in accordance with 130.2(A),
an energized electrical work permit shall be required under the
following condiƟons:
1. When work is performed within the restricted approach boundary
2. When the employee interacts with the equipment when conductors or circuit
parts are not exposed but an increased likelihood of injury from an exposure to
an arc Ňash hazard exists
Required by OSHA / 70E®
• If the voltage is greater than 50 volts
Category RaƟng
CAT I
Use
Protected electronic equipment; high-voltage, low-energy
sources derived from a high-winding resistance transformer.
CAT II
1-phase receptacle connected loads; appliances, portable
tools, outlets at more than 30 feet from CAT III source or
more than 60 feet from CAT IV source.
CAT III
3-phase distribuƟon, including single-phase commercial
lighƟng; switchgear, polyphase motors, bus and feeders,
lighƟng systems in larger buildings.
CAT IV
3-phase at uƟlity connecƟon, any outdoor conductors;
“Origin of installaƟon”, electricity meters, service drop
from pole to building, overhead lines etc.
• If equipment can not be placed in an electrically safe work condiƟon
• Work is considered energized electrical work and can be performed by written permit only
• Can only be Įlled out by qualiĮed persons
• Example of Work Permit in Annex J of the NFPA 70E®
ExcepƟons
• TesƟng, troubleshooƟng, and voltage measuring
• Thermography and visual inspecƟons if the restricted approach boundary is not
crossed
• Access to and egress from an area with energized electrical equipment if no
electrical work is performed and the restricted approach boundary is not crossed
• General housekeeping and miscellaneous non-electrical tasks if the restricted
approach boundary is not crossed
AlternaƟng Current (AC): Current that Ňows in one direcƟon, then reverses and Ňows in the
opposite direcƟon.
Ampere: Amps (I): The unit of measure of electrical current, the part of electricity that results
in work or expended energy.
Conductor: An electrical property that allows the Ňow of electricity. Any element with one
free electron in the outermost orbit.
Direct Current (DC): Current that Ňows in only one direcƟon.
Frequency: The number of Ɵmes a sine wave repeats in one second. Also known as cycles or
Hertz (Hz).
Harmonics: AddiƟonal sine waves generated from the original sine wave. Third harmonics
may cause overheaƟng problems in electrical circuits.
InducƟon: The process in which an AC magneƟc Įeld causes a voltage and current to Ňow in
another separate circuit within that magneƟc Įeld.
Insulator: An electrical property that restricts the Ňow of electricity. Any element that has
Įve or more electrons in the outermost orbit.
MulƟmeter: An electrical instrument that can measure voltage, current, and resistance.
Ohm: The unit of measure of resistance in an electrical circuit.
Overload: CondiƟon in which the current raƟng of the load is exceeded. The load aƩempts
to perform more work than that for which it is designed.
Phase (Ø): The live, or hot conductor. Especially if there is more than one, such as 3 phase(Ø).
Polarity: The relaƟonship of one coil or winding to another, clockwise and counter-clockwise.
PotenƟal: The presence of voltage between two conductors.
Resistance: The opposiƟon of current Ňow measured in ohms (ɏ).
Resistor: A solid state device with a designated amount of resistance.
Service: The entrance, or connecƟng point, for the power source of a building.
Short Circuit: A circuit that has no load between the hot and neutral conductors.
Transformer: An electrical device, with no moving parts, that can change the voltage level.
Volt: The unit of measure of voltage (E).
WaƩ: The unit of measure of power used in a circuit.
I=E/R
I=P/E
E2/ R E / R
I
P=ExI
2
X
P/E
R
EXI
P
I
P X R
E
R
P / R
E/I
2
P/I
E /P
I X R P / I2
R=E/I
E=P/I
E=IxR
T
PC
TRAINCO
Real World Training...for Real World Needs