IEEE Std 1584
-2018. IEEE Guide for Performing
NFPA® 70E – Standard for Electrical Safety in the Workplace has been revised. The requirements in this document are being enforced by OSHA and other state run
OSHA organizations.
This method IEEE 1584-2018 has proven to be more accurate and wider application range.
arc : A plasma cloud formed in a gap between two electrodes with sufficient potential difference.
arc flash : An electric arc event with thermal energy dissipated as radiant, convective, and conductive heat.
arc-flash boundary : A distance from a prospective arc source at which the incident energy is calculated to be 5.0 J/cm
2
(1.2 cal/cm
2
).
available short-circuit current : At a given point in a circuit, the maximum current that the power system can deliver through a given circuit to any negligible-impedance short circuit applied at the given point, or at any other point that causes the highest current to flow through the given point. “Available short-circuit current” and “bolted fault current” are equivalent for a zero fault impedance.
bolted fault : A short-circuit condition that assumes zero impedance exists at the point of the fault.
clearing time : The total time between the beginning of a specified overcurrent and the final interruption of the circuit at rated voltage
NOTE 1—In regard to fuses, it is the sum of the minimum melting time of a fuse plus tolerance and the arcing time. In regard to circuit breakers with integral trip units (usually rated less than 1000 V), it is the sum of the sensor time, plus opening time and the arcing time. For circuit breakers with separate relaying (usually rated greater than 1000 V), it is the sum of the minimum relay time, plus contact parting time and the arcing time. Sometimes referred to as total clearing time or interrupting time.
NOTE 2—Arc duration is the interval of time between the instant of the first initiation of the arc and the instant of final arc extinction. Arc duration is usually the same or directly related to the clearing time. See 6.9.1 for special circumstances where arc duration may be different than clearing time.
electrode configuration : The orientation and arrangement of the electrodes used in the testing performed for the model development.
NOTE 1. Electrodes were placed in open-air (“OA”) or enclosed (“Box”) configurations (with open front end). Electrodes were also oriented vertically and horizontally. Open-tipped and barrier-terminated electrode configurations were also used.
NOTE 2. Refer to Annex G . The following electrode configurations (test arrangements) are defined and listed according to their order of use within the incident energy model:
— VCB: Vertical conductors/electrodes inside a metal box/enclosure
— VCBB: Vertical conductors/electrodes terminated in an insulating barrier inside a metal box/enclosure
— HCB: Horizontal conductors/electrodes inside a metal box/enclosure
— VOA: Vertical conductors/electrodes in open air
— HOA: Horizontal conductors/electrodes in open air incident energy : The amount of thermal energy impressed on a surface, a certain distance from the source, generated during an electric arc event.
NOTE 1. The incident energy is calculated at the working distance. Incident energy increases as the distance from the potential arc source decreases, and the incident energy decreases as the distance increases. See: working distance .
NOTE 2. The units used to measure incident energy are joules per square centimeter (J/cm
2
) or calories per square centimeter (cal/cm
2
). See B.2
.
working distance : The distance between the potential arc source and the face and chest of the worker performing the task.
NOTE. Parts of the body closer to the potential arc source other than the face and chest receive a greater incident energy. The arc source is usually energized parts within an equipment enclosure or exposed energized parts in open air.

Arc Flash Hazard: A source of possible injury or damage to health associated with the release of energy caused by an electric arc.
Informational Note No. 1: The likelihood of occurrence of an arc flash incident increases when energized electrical conductors or circuit parts are exposed or when they are within equipment in a guarded or enclosed condition, provided a person is interacting with the equipment in such a manner that could cause an electric arc. An arc flash incident is not likely to occur under normal operating conditions when enclosed energized equipment has been properly installed and maintained.
Informational Note No. 2: See Table 130.5(C) for examples of tasks that increase the likelihood of an arc flash incident occurring
Boundary, Arc Flash: When an arc flash hazard exists, an approach limit from an arc source at which incident energy equals 1.2 cal/cm2
(5 J/cm2).
Informational Note: According to the Stoll skin burn injury model, the onset of a second degree burn on unprotected skin is likely to occur at an exposure of 1.2 cal/cm2 (5 J/cm2) for one second.
A calorie is the energy required to raise one gram of water one degree Celsius at one atmosphere. Second degree burns occur at 1.2 calories per centimeter squared per second. One calorie per centimeter squared per second can be equal to holding your finger over the tip of the flame of a cigarette lighter for one second.
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.
Enclosed . Surrounded by a case, housing, fence, or wall(s) that prevents persons from unintentionally contacting energized parts
Enclosure. The case or housing of apparatus or the fence or walls surrounding an installation to prevent personnel from unintentionally contacting energized electrical conductors or circuit parts or to protect the equipment from physical damage.
Fault Current. The amount of current delivered at a point on the system during a short-circuit condition.
Fault Current, Available . The largest amount of current capable of being delivered at a point on the system during a short-circuit condition.
Informational Note No. 1: A short circuit can occur during abnormal conditions such as a fault between circuit conductors or a ground fault. See Figure 100.0.
Informational Note No. 2: If the dc supply is a battery system, the term available fault current refers to the prospective short-circuit current.
Maintenance, Condition of . The state of the electrical equipment considering the manufacturers’ instructions, manufacturers’ recommendations, and applicable industry codes, standards, and recommended practices
Qualified Person . One who has demonstrated skills and knowledge related to the construction and operation of electrical equipment and installations and has received safety training to identify the hazards and reduce the associated risk.
Risk Assessment . An overall process that identifies hazards, estimates the likelihood of occurrence of injury or damage to health, estimates the potential severity of injury or damage to health, and determines if protective measures are required.
Informational Note: As used in this standard, arc flash risk assessment and shock risk assessment are types of risk assessments
Shock Hazard. A source of possible injury or damage to health associated with current through the body caused by contact or approach to energized electrical conductors or circuit parts.
Informational Note: Injury and damage to health resulting from shock is dependent on the magnitude of the electrical current, the power source frequency (e.g., 60 Hz, 50 Hz, dc), and the path and time duration of current through the body.
The physiological reaction ranges from perception, muscular contractions, inability to let go, ventricular fibrillation, tissue burns, and death.
Working Distance. The distance between a person’s face and chest area and a prospective arc source.
Informational Note: Incident energy increases as the distance from the arc source decreases. See 130.5(C)(1) for further information.
105.3(A) Employer Responsibility. The employer shall have the following responsibilities:
(1) Establish, document, and implement the safety-related work practices and procedures required by this standard.
(2) Provide employees with training in the employer’s safetyrelated work practices and procedures.
105.3(B) Employee Responsibility. The employee shall comply with the safety-related work practices and procedures provided by the employer.
105.4 Priority. Hazard elimination shall be the first priority in the implementation of safety related work practices.
110.1(B) Inspection. The electrical safety program shall include elements to verify that newly installed or modified electrical equipment or systems have been inspected to comply with applicable installation codes and standards prior to being placed into service.
110.1(H) Risk Assessment Procedure. The electrical safety program shall include a risk assessment procedure and shall comply with 110.1
(H)(1) through 110.1
(H)(3).
110.1(H)(2) Human Error. The risk assessment procedure shall address the potential for human error and its negative consequences on people, processes, the work environment, and equipment.
110.1(H)(3) Hierarchy of Risk Control Methods. The risk assessment procedure shall require that preventive and protective risk control methods be implemented in accordance with the following hierarchy:
(1) Elimination (2) Substitution (3) Engineering controls (4) Awareness (5) Administrative controls (6) PPE
Table 130.4(D)(a) shall be used for the distances associated with various ac system voltages.
Table 130.4(D)(b) shall be used for the distances associated with various dc system voltages.

130.5(H) Equipment Labeling: Electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers that are in other than dwelling units and that are likely to require examination, adjustment, servicing, or maintenance while energized shall be marked with a label containing all the following information
(1) Nominal system voltage
(2) Arc flash boundary
(3) At least one of the following: a. Available incident energy and the corresponding working distance, or the arc flash PPE category in Table 130.7(C)(15)(a) or Table 130.7(C)(15)(b) for the equipment, but not both b. Minimum arc rating of clothing c. Site-specific level of PPE

130.5(E)(2) The arc flash boundary shall be permitted to be determined by Table 130.7(C)(15)(a) or Table 130.7(C)(15)(b) when the requirements of these tables apply.
There are two methods that can be used in an arc flash risk assessment to determine the arc flash boundary.
- The incident energy analysis method, which results in an arc flash boundary at a distance where the incident energy is 1.2 cal/cm2.
- The other is the arc flash PPE category method, which results in an arc flash boundary selected directly from the tables in 130.7(C)(15).
Arc Flash PPE Category Method. The requirements of 130.7(C)(15) shall apply when the arc flash PPE category method is used for the selection of arc flash PPE.
TABLE 130.7(C)(15)(a) Arc-Flash PPE Categories for AC
TABLE 130.7(C)(15)(b) Arc-Flash PPE Categories for DC
TABLE 130.7(C)(15)(c) Personal Protective Equipment (PPE) is not applicable to evaluations conducted using the incident energy analysis method. For arc flash PPE clothing requirements for the incident energy analysis method, see 130.5(G) and 130.7(C)(1) though (C)(14).
130.5(F) Arc Flash PPE. One of the following methods shall be used for the selection of arc flash PPE:
(1) The incident energy analysis method in accordance with 130.5(G)
(2) The arc flash PPE category method in accordance with 130.7(C)(15)
Either, but not both, methods shall be permitted to be used on the same piece of equipment. The results of an incident energy analysis to specify an arc flash PPE category in Table 130.7(C)(15)(c) shall not be permitted.
130.5(G) Incident Energy Analysis Method
The incident energy analysis shall take into consideration the characteristics of the overcurrent protective device and its fault clearing time, including its condition of maintenance.
The incident energy analysis shall be updated when changes occur in the electrical distribution system that could affect the results of the analysis. The incident energy analysis shall also be reviewed for accuracy at intervals not to exceed 5 years.
*Use Table 130.5(G) For PPE when using this method
Limited Approach
The Limited Approach Boundary indicates where an electric shock could occur. It should be entered only by qualified persons or unqualified persons that have been advised and are escorted by a qualified person.
Restricted Approach
A heightened risk of electric shock exists inside the Restricted Approach Boundary. Only qualified persons should enter this space.
Requires the use of shock protection techniques and PPE.

Voltage three-phase (line-to-line)
Voc ≔ 13.2
kV
Tests were performed in laboratory conditions using selected open-circuit voltages ( V oc
). While the model utilizes V oc
, pre-fault voltage (system nominal voltage, utilization voltage, etc.) can be used for application of this model.
Gaps between conductors
G ≔ 152 mm
Bolted fault current for three-phase faults (symmetrical rms) (kA)
I bf
≔ 8.606
kA
NOTE: the arc duration is obtained from the interpolation arcing current (see below):
RelayModel ≔ 1
(:=1 is "Yes" := 0 is "No")
Working distances
D ≔ 914.4
mm
An upper limit on the working distance is not considered necessary. The incident energy was measured at several working distances to be able to determine an accurate relationship of distance versus incident energy for each configuration at different voltage levels. The minimum working distance should be no less than 304.8 mm (12 in). Any smaller working distance could place the worker within the range of the arc plasma cloud and metal droplets. No tests were performed at such short working distances. A minimum working distance of 304.8 mm (12 in) was used because it is considered that the plasma cloud is not considered to have exceeded a radius of 304.8 mm (12 in). The plasma cloud size and effect of direct contact with it should be considered in future arc-flash model revisions.

Height ≔ 1143 mm
Width ≔ 762 mm
Depth ≔ 762 mm
Electrode configurations
EC ≔ “VCB”
Conductor/electrode configurations:
VCB: vertical electrodes inside a metal box/enclosure (2002)
VOA: vertical electrodes in open air (2002)
VCBB: vertical electrodes terminated in an insulating
-
barrier inside a metal box/enclosure
HCB: horizontal electrodes inside a metal box / enclosure
HOA: horizontal electrodes in open air

Maximum height or width: 1,244.6 mm (49 in).
Height max
≔ 49 in
Width max
≔ 49 in
Maximum opening area: 1.549 m² (2,401 in²).
Area max
≔ Height max
⋅ Width max
= 1.549
m
2
Minimum width > 4 x gap between conductors
Width min
≔ 4 ⋅ G = 608 mm
Valid_D = “Accepted”
Valid_Modelo = “Apply the model”
Valid_Width = “Accepted”
Area calculated
≔ ⋅ = 0.871
m
2
C
SWGR
≔ if Area calculated
‖
‖ 1
> Area max else
‖
‖ 0
= 0
Height ≔ if Height > Height max
∧ C
SWGR
＝ 1
‖
‖
Height max else
‖
‖
Height
= 1143 mm
Area calculated
≔ ⋅ = 0.871
m
2
Width ≔ if Width > Width max
∧ C
SWGR
＝ 1
‖
‖
Width max else
‖
‖
Width
= 762 mm
Area calculated
≔
Area max
= 1.549
m
2
⋅ = 0.871
m
2

EC = “VCB”
I arc_600Voc
≔ 10
⎛⎝ k
1
+ k
2
⋅ log ⎛⎝ k bf
⎞⎠ + k
3
⋅ log ⎛⎝ k
G
⎞⎠⎞⎠
⋅
⎝ k
4
⋅ k bf
6
+ k
5
⋅ k bf
5
+ k
6
⋅ k bf
4
+ k
7
⋅ k bf
3
+ k
8
⋅ k bf
2
+ k
9
⋅ k bf
+ k
10 kA
I arc_600Voc
= 6.1129
kA
I arc_2700Voc
≔ 10
⎛⎝ k
1
+ k
2
⋅ log ⎛⎝ k bf
⎞⎠ + k
3
⋅ log ⎛⎝ k
G
⎞⎠⎞⎠
⋅
⎝ k
4
⋅ k bf
6
+ k
5
⋅ k bf
5
+ k
6
⋅ k bf
4
+ k
7
⋅ k bf
3
+ k
8
⋅ k bf
2
+ k
9
⋅ k bf
+ k
10
⎞ kA
I arc_2700Voc
= 7.3708
kA
I arc_14300Voc
≔ 10
⎛⎝ k
1
+ k
2
⋅ log ⎛⎝ k bf
⎞⎠ + k
3
⋅ log ⎛⎝ k
G
⎞⎠⎞⎠
⋅
⎝ k
4
⋅ k bf
6
+ k
5
⋅ k bf
5
+ k
6
⋅ k bf
4
+ k
7
⋅ k bf
3
+ k
8
⋅ k bf
2
+ k
9
⋅ k bf
+ k
10 kA
I arc_14300Voc
= 8.0958
kA

Calculate a second set of arc duration , using the reduced arcing current I arc_min to determine if the arcing current variation has an effect on the operating time of protective devices and consequently incident energy. The arcing current variation applies for all system open-circuit voltages within the valid range of the model (208 V to 15 000 V), but it is expected to have the most impact between 208 V and 600 V.
To determine a lower bound of the average rms arcing current, use Equation (2) as follows and the coefficients provided in Table 2 :
EC = “VCB”
VarC f
≔ k
1
⋅ k
Voc
6
+ k
2
⋅ k
Voc
5
+ k
3
⋅ k
Voc
4
+ k
4
⋅ k
Voc
3
+ k
5
⋅ k
Voc
2
+ k
6
⋅ k
Voc
+ k
7
= 0.0246
1 0.5
⋅ VarC f
= 0.9877
I arc_600Voc_min
≔ I arc_600Voc
I arc_600Voc_min
= 6.0379
kA
⋅ 0.5
⋅ VarC f
⎞⎠
I arc_2700Voc_min
≔ I arc_2700Voc
I arc_2700Voc_min
= 7.2803
kA
⋅ 0.5
⋅ VarC f
⎞⎠
I arc_14300Voc_min
≔ I arc_14300Voc
I arc_14300Voc_min
= 7.9964
kA
⋅ 0.5
⋅ VarC f
⎞⎠
0.5
⋅ VarC f
= 1.23
%
oc
arc
oc
arc_600Voc
arc_2700Voc
arc_14300Voc
arc

I arc_1
≔
I arc_2700Voc
I arc_600Voc
――――――― ⋅
2.1
⎛⎝ k
Voc
2.7⎞⎠ + I arc_2700Voc
I arc_2
≔
I arc_14300Voc
-
――――――――
11.6
I arc_2700Voc
⎛⎝ k
Voc
14.3⎞⎠ + I arc_14300Voc
I arc_3
≔
I arc_1
―― ⋅
2.1
⎛⎝ 2.7
k
Voc
⎞⎠ +
I arc_2
―― ⋅
2.1
⎛⎝ k
Voc
0.6⎞⎠
I arc_1_min
≔
I arc_2700Voc_min
-
――――――――――
2.1
I arc_600Voc_min
⎛⎝ k
Voc
2.7⎞⎠ + I arc_2700Voc_min
I arc_2_min
≔
I arc_14300Voc_min
-
11.6
I arc_2700Voc_min
―――――――――― ⎛⎝ k
Voc
14.3⎞⎠ + I arc_14300Voc_min
I arc_3_min
≔
I arc_1_min
――― ⋅
2.1
⎛⎝ 2.7
k
Voc
⎞⎠ +
I arc_2_min
――― ⋅
2.1
⎛⎝ k
Voc
0.6⎞⎠
I arc_1_min
= 13.4925
kA
I arc_2_min
= 7.9285
kA
I arc_3_min
= -19.8913
kA
208 V ≤ V oc
≤ 600 V
I arc_208Voc_min
= 8.4917
kA I arc_208Voc
= 8.5973
kA
I arc_1
= 13.6602
kA
I arc_2
= 8.0271
kA
I arc_3
= -20.1385
kA
I bf
= 8.606
kA I arc_min
= 7.9285
kA I arc
= 8.0271
kA
The arc duration is obtained from the interpolation arcing current:
I arc_min
= 7.9285
kA
T arc_min
≔ t ⎛⎝ I arc_min
= ms or
T' ≔ T arc_min
(if Relay Model=1 then T':=T arc_min else T´:=cycle/f)
I arc
= 8.0271
kA
T arc
≔ t ⎛⎝ I arc
= ms or
T ≔ T arc
(if RelayModel=1 then T:=Tarc else T:=cycle/f)

Determination of equivalent height and width (VCB, VCBB, HCB)
Width = 30 in
Width
1
= 747.776
mm
Width
1
= 29.44
in
Height = 45 in Depth = 30 in
Height
1
= 1142.9977
mm
Height
1
= 44.9999
in
208 V ≤ V oc < 600 V.
If Shallow = 0 then is
"Typical Enclosure".
Shallow = 0
Height
1
+ Width
1
EES ≔ ――――――
2
EES = 37.22
in
Determination of enclosure size correction factor ( CF )
EC = “VCB” b
1
= -0.000302
b
2
= 0.03441
b
3
= 0.4325
CF = 1.2949
1
――
CF
0.7723

EC = “VCB”
E
600Voc
≔
⎛
⎜
⎜⎝
12.552
50
⋅ k
T
⋅ 10
⎛
⎜
⎜⎝ k
1
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k bf
5 k
3
+
⋅ k k
7
Iarc_600Voc
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
+ k
10
⋅ k bf
+ k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
12
⋅ log ⎛⎝ k
D
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_600Voc
+
⎛
⎜
⎝
1
――
CF
⎞ ⎞
⎟
⎠
⎟
⎟⎠
⎞
⎟
⎟⎠
J
―― cm
2
E
208Voc
≔
⎛
⎜
⎜⎝
12.552
50
⋅ k
T
⋅ 10
⎛
⎜
⎜⎝ k
1
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k bf
5 k
3
+
⋅ k k
7
Iarc_600Voc
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
+ k
10
⋅ k bf k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
12
⋅ log ⎛⎝ k
D
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_208Voc
⎛
⎜
⎝
1
――
CF
⎞
⎟
⎠
⎞
⎟
⎟⎠
⎞
⎟
⎟⎠
J
―― cm
2
E
600Voc
' ≔
⎛
⎜
⎜⎝
12.552
50
⋅ k
T'
⋅ 10
⎛
⎜
⎜⎝ k
1
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k k bf
3
5
⋅ k
+
Iarc_600Voc_min k
7
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
+ k
10
⋅ k bf
+ k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
12
⋅ log ⎛⎝ k
D
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_600Voc_min
+
⎛
⎜
⎝
1
――
CF
⎞
⎟
⎠
⎞
⎟
⎟⎠
⎟⎠
⎞
⎟ J
―― cm
2
I arc_600Voc_min
= 6.0379
kA
T' = 120 ms
I arc_600Voc
= 6.1129
kA
T = 120 ms
E
600Voc
J
' = 3.054 ―― cm
2
E
600Voc
=
J
3.191 ―― cm
2
E
208Voc
' ≔
⎛
⎜
⎜⎝
12.552
50
⋅ k
T'
⋅ 10
⎛
⎜
⎜⎝ k
1
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k bf
5 k
3
+
⋅ k k
7
Iarc_600Voc
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
+ k
10
⋅ k bf
+ k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
12
⋅ log ⎛⎝ k
D
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_208Voc_min
+
⎛
⎜
⎝
1
――
CF
⎞ ⎞
⎟
⎠
⎟
⎟⎠
⎞
⎟
⎟⎠
J
―― cm
2
I arc_208Voc_min
= 8.4917
kA
T' = 120 ms
I arc_208Voc
= 8.5973
kA
T = 120 ms
E
208Voc
J
' = 4.37 ―― cm
2
E
208Voc
=
J
4.422 ―― cm
2
208 V ≤ V oc
≤ 600 V
AFB
600Voc
≔ 10
⎛
⎜
⎜
⎜ k
1
+ k
2
⋅ log ⎛⎝ k k
5 k
7
⋅ k bf
3
+ k
9
⋅ k bf
2
+ k
10
⋅ k bf k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_600Voc
⎛
⎜
⎝
1
CF
⎞
⎝
G
+ k
3
⋅ k
Iarc_600Voc k
4
⋅ k bf
7
+ ⋅ k bf
6
+ k
6
⋅ k bf
5
+ ⋅ k bf
4
+ k
8
k
12
――
⎠ log
⎛
⎜
20 ⎞
⎟
⎝ k
T
⎠
⎞
⎟
⎟
⎟
⎠ mm
AFB
208Voc
≔ 10
⎛
⎜
⎜
⎜
⎝ k
1
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k bf
5 k
3
+
⋅ k k
7
Iarc_600Voc
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2 k
10 k
+
⎛
⎜
⎝
20 k
T
⎞
⎟
⎠
――――――――――――――――――――――――――――――――――――――――――――――
k
12
+ ⋅ bf k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_208Voc
+
⎛
⎜
⎝
1 ⎞
――
CF ⎠ log
⎞
⎟
⎟
⎟
⎠ mm
AFB
600Voc
' ≔ 10
⎜
⎜
⎝
⎛
⎜ k
1
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k k bf
3
5
⋅ k
+
Iarc_600Voc_min k
7
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
+ k
10
⋅ k bf
+ k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_600Voc_min
+
⎛
⎜
⎝
1
――
CF
⎞
⎟
⎠ log
⎛
⎜
⎝
――――――――――――――――――――――――――――――――――――――――――――――――
k
12
20 k
T'
⎞
⎟
⎠
⎞
⎟
⎟
⎟
⎠ mm
I arc_600Voc_min
= 6.0379
kA
AFB
600Voc
' = 669.957
mm
T' = 120 ms
I arc_600Voc
= 6.1129
kA
T = 120 ms
AFB
600Voc
= 688.539
mm
AFB
208Voc
' ≔ 10
⎜
⎜
⎛
⎜
⎝ k
1
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k bf
5 k
3
+
⋅ k k
7
Iarc_600Voc
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
k
12
+ k
10
⋅ k bf k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_208Voc_min
⎛
⎜
⎝
1
――
CF
⎞
⎟
⎠ log
⎛
⎜
⎝
20 ⎞
―― k
T'
⎟
⎠
⎞
⎟
⎟
⎟
⎠ mm
I arc_208Voc_min
= 8.4917
kA
T' = 120 ms
AFB
208Voc
' = 838.333
mm
I arc_208Voc
= 8.5973
kA
AFB
208Voc
= 844.558
mm
T = 120 ms
208 V ≤ V oc
≤ 600 V

E
2700Voc
≔
⎛
⎜
⎜⎝
12.552
50
⋅ k
T
⋅ 10
⎛
⎜
⎜⎝ k
1
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k bf k
5
3
⋅
+ k k
Iarc_2700Voc
7
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
+ k
10
⋅ k bf
+ k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
12
⋅ log ⎛⎝ k
D
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_2700Voc
+
⎛
⎜
⎝
1 ⎞
――
⎠
⎞
CF
⎟
⎟⎠
⎞
⎟
⎟⎠
J
―― cm
2
E
2700Voc
' ≔
⎛
⎜
⎜⎝
12.552
―――
50 k
T'
⋅ 10
⎛
⎜ k
1
⎜⎝
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k k
3 bf
5
⋅ k
+
Iarc_2700Voc_min k
7
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
+ k
10
⋅ k bf
+ k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
12
⋅ log ⎛⎝ k
D
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_2700Voc_min
+
⎛
⎜
⎝
1
――
CF
⎞
⎟
⎠
⎞
⎟
⎟⎠
⎞
⎟
⎟⎠
J
―― cm
2
For
I arc_2700Voc_min
= 7.2803
kA and
T' = 120 ms
For
I arc_2700Voc
= 7.3708
kA and
T = 120 ms
E
2700Voc
J
' = 4.359 ―― cm
2
E
2700Voc
=
J
4.452 ―― cm
2
AFB
2700Voc
≔ 10
⎛
⎜
⎜
⎜
⎝ k
1
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k bf k
5
3
⋅
+ k k
Iarc_2700Voc
7
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
+ k
10
⋅ k bf
+ k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_2700Voc
+
⎛
⎜
⎝
1 ⎞
――
CF ⎠ log
⎛
⎜
⎝
20 k
T
⎞
⎟
⎠
――――――――――――――――――――――――――――――――――――――――――――――
k
12
⎞
⎟
⎟
⎟
⎠ mm
AFB
2700Voc
' ≔ 10
⎛
⎜
⎜
⎜
⎝ k
1
+ k
2
⋅ log ⎛⎝ k
G k
3
⋅ k
⎞⎠ ―――――――――――――――――――――― k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k bf
5
+ k
7
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
k
12
+ k
10
⋅ k bf k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_2700Voc_min
⎛
⎜
⎝
1
――
CF
⎞
⎠ log
⎛
⎜
⎝
20
―― k
T'
⎞
⎟
⎠
――――――――――――――――――――――――――――――――――――――――――――――――
⎞
⎟
⎟
⎟
⎠ mm
For
I arc_2700Voc_min
= 7.2803
kA and
T' = 120 ms
AFB
2700Voc
' = 835.603
mm
For
I arc_2700Voc
= 7.3708
kA
AFB
2700Voc
= 846.92
mm and
T = 120 ms
E
14300Voc
≔
⎛
⎜
⎜⎝
12.552
50
⋅ k
T
⋅ 10
⎛
⎜
⎜⎝ k
1
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k bf k
5
3
⋅
+ k k
Iarc_14300Voc
7
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
+ k
10
⋅ k bf k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
12
⋅ log ⎛⎝ k
D
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_14300Voc
⎛
⎜
⎝
1
――
CF
⎞ ⎞
⎟
⎠
⎟
⎟⎠
⎞
⎟
⎟⎠
J
―― cm
2
E
14300Voc
' ≔
⎛
⎜
⎜⎝
12.552
50
⋅ k
T'
⋅ 10
⎛
⎜
⎜⎝ k
1
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k k
3 bf
5
⋅ k
+
Iarc_14300Voc_min k
7
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
+ k
10
⋅ k bf k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
12
⋅ log ⎛⎝ k
D
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_14300Voc_min
For
I arc_14300Voc_min
= 7.9964
kA and
T' = 120 ms
⎛
⎜
⎝
1
――
CF
⎞ ⎞
⎟
⎠
⎟
⎟⎠
⎞
⎟
⎟⎠
J
―― cm
2
For
I arc_14300Voc
= 8.0958
kA and
T = 120 ms
E
14300Voc
J
' = 5.075 ―― cm
2
E
14300Voc
=
J
4.995 ―― cm
2
AFB
14300Voc
≔ 10
⎛
⎜
⎜
⎜
⎝ k
1
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k bf k
5
3
⋅
+ k k
Iarc_14300Voc
7
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
k
12
+ k
10
⋅ k bf
+ k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_14300Voc
+
⎛
⎜
⎝
1
――
CF
⎞
⎟
⎠ log
⎛
⎜
⎝
20
―― k
T
⎞
⎟
⎠
⎞
⎟
⎟
⎟
⎠ mm
AFB
14300Voc
' ≔ 10
⎛
⎜
⎜
⎜
⎝ k
1
+ k
2
⋅ log ⎛⎝ k
G
+ k
4
⋅ k bf
7
+ k
5
⋅ k bf
6
+ k
6
⋅ k k
3 bf
5
⋅ k
+
Iarc_14300Voc_min k
7
⋅ k bf
4
+ k
8
⋅ k bf
3
+ k
9
⋅ k bf
2
+
k
12 k
10
⋅ k bf k
11
⋅ log ⎛⎝ k bf
⎞⎠ + k
13
⋅ log ⎛⎝ k
Iarc_14300Voc_min
⎛
⎜
⎝
1
――
CF
⎞
⎟
⎠ log
⎛
⎜
⎝
20 k
T'
⎞
⎟
⎠
⎞
⎟
⎟
―――――――――――――――――――――――――――――――――――――――――――――――――
⎠ mm
For
I arc_14300Voc_min
= 7.9964
kA and
T' = 120 ms
AFB
14300Voc
' = 920.652
mm
For
I arc_14300Voc
= 8.0958
kA
AFB
14300Voc
= 911.444
mm and
T = 120 ms

E
1
≔
E
2700Voc
-
――――――
2.1
E
600Voc
⎛⎝ k
Voc
2.7⎞⎠ + E
2700Voc
E
2
≔
E
14300Voc
E
2700Voc
―――――― ⋅
11.6
⎛⎝ k
Voc
14.3⎞⎠ + E
14300Voc
E
3
≔
E
1
――
2.1
⎛⎝ 2.7
k
Voc
⎞⎠ +
E
2
――
2.1
⎛⎝ k
Voc
0.6⎞⎠
E
1
' ≔
E
2700Voc
' -
600Voc
'
――――――
2.1
E
⎛⎝ k
Voc
2.7⎞⎠ + E
2700Voc
'
E
2
' ≔
E
14300Voc
' -
―――――――
11.6
E
2700Voc
'
⎛⎝ k
Voc
14.3⎞⎠ + E
14300Voc
'
E
3
' ≔
E
1
――
2.1
'
⎛⎝ 2.7
k
Voc
⎞⎠ +
E
2
――
2.1
'
⎛⎝ k
Voc
0.6⎞⎠
E
1
J
' = 10.8818 ―― cm
2
E
2
J
' = 5.0068 ―― cm
2
E
3
J
' = -24.3678 ―― cm
2
E
1
=
J
10.7572 ―― cm
2
E
2
=
J
4.9438 ―― cm
2
E
3
=
J
-24.1231 ―― cm
2
For
I arc_min
= 7.9285
and
T' = 120 ms kA
@
Voc = 13.2
kV
J
E' = 5.0068 ―― cm
2 cal
E' = 1.1959 ―― cm
2
For
I arc
= 8.0271
and
T = 120 ms kA
@
Voc = 13.2
kV
J
E = 4.9438 ―― cm
2 cal
E = 1.1808 ―― cm
2

AFB
1
≔
AFB
2700Voc
-
――――――――
2.1
AFB
600Voc
⎛⎝ k
Voc
2.7⎞⎠ + AFB
2700Voc
AFB
2
≔
AFB
14300Voc
AFB
2700Voc
―――――――― ⋅
11.6
⎛⎝ k
Voc
14.3⎞⎠ + AFB
14300Voc
AFB
3
≔
AFB
1
――
2.1
⋅ ⎛⎝ 2.7
k
Voc
⎞⎠ +
AFB
2
――
2.1
⋅ ⎛⎝ k
Voc
0.6⎞⎠
AFB
1
' ≔
AFB
2700Voc
' AFB
――――――――
2.1
600Voc
'
⎛⎝ k
Voc
2.7⎞⎠ + AFB
2700Voc
'
AFB
2
' ≔
AFB
14300Voc
' -
―――――――――
11.6
AFB
2700Voc
'
⎛⎝ k
Voc
14.3⎞⎠ + AFB
14300Voc
'
AFB
3
' ≔
AFB
―――
2.1
1
'
⎛⎝ 2.7
k
Voc
⎞⎠ +
AFB
―――
2.1
2
'
⎛⎝ k
Voc
0.6⎞⎠
AFB
1
' = 1663.831
mm
AFB
2
' = 912.587
mm
AFB
3
' = -2843.635
mm
AFB
1
= 1638.825
mm
AFB
2
= 905.326
mm
AFB
3
= -2762.17
mm
For
I arc_min
= 7.9285
and
T' = 120 ms kA
@
Voc = 13.2
kV
AFB' = 0.913
m AFB' = 35.9286
in
For
I arc
= 8.0271
and
T = 120 ms kA
@
Voc = 13.2
kV
AFB = 0.905
m AFB = 35.6427
in

The National Fire Protection Association (NFPA) details how to comply with the Occupational Safety and Health Administration's (OSHA) regulation, 29 CFR 1910.333(a), through the NFPA 70E standard.
According to the NFPA 70E standard, there are six primary responsibilities that facilities must meet. These responsibilities include:
- Training for employees
- Written safety program in place that is actionable
- Personal Protective Equipment (PPE) available for employees
- Insulated tools
- Arc flash hazard degree calculations
- Properly labeled equipment
Arc flash labeling is the responsibility of the employer, not the manufacturer or installer of the equipment. Labeling is required for any piece of electrical equipment that may need examination, adjustment, service or maintenance while energized, creating the potential for an arc flash incident to occur.
Sample Label. NOTE: PPE “LEVEL 1” specified on this label is a site specific level of PPE

TABLE 130.7(C)(15)(c) Personal Protective Equipment (PPE) is not applicable to evaluations conducted using the incident energy analysis method. For arc flash PPE clothing requirements for the incident energy analysis method, see 130.5(G) and 130.7(C)(1) though (C)(14).
(no PPE Category 0)
If you are using the incident energy method to select your arc flash PPE the recreated NFPA 70E Table 130.5(G) listed below can be used as a reference. Please reference NFPA 70E Standards for Electrical Safety in the Workplace directly for any specific questions on the guidelines listed in this FAQ.
Table 130.5(G) identifies the arc-rated clothing and other PPE requirements…and used with the incident energy analysis method of selecting arc flash PPE.
- No PPE specified for less than 1.2 cal/cm2
- PPE for 1.2 cal/cm2 to 12 cal/cm2
- PPE for greater than 12 cal/cm2
Incident energy exposures equal to 1.2 cal/cm2 up to 12 cal/cm2
Arc-rated clothing with an arc rating equal to or greater than the estimated incident energy level.
Long-sleeve shirt and pants or coverall or arc flash suit
Arc-rated face shield and arc-rated balaclava or arc flash suit
Arc-rated outerwear (e.g. jacket, parka, rainwear, hard hat liner)
Heavy-duty leather gloves, arc-rated gloves, or rubber insulating gloves with leather protectors
Hard hat
Safety Glasses or safety goggles
Hearing protection
Leather footwear
Incident energy exposures greater than 12 cal/cm2
Arc-rated clothing with an arc rating equal to or greater than the estimated incident energy level.
Long-sleeve shirt and pants or coverall or arc flash suit
Arc-rated arc flash suit hood
Arc-rated outerwear (e.g. jacket, parka, rainwear, hard hat liner)
Arc-rated gloves or rubber insulating gloves and leather protectors
Hard hat
Safety Glasses or safety goggles
Hearing protection
Leather footwear

130.5 Arc Flash Risk Assessment.
(A) General. An arc flash risk assessment shall be performed:
(1) To identify arc flash hazards
(2) To estimate the likelihood of occurrence of injury or damage to health and the potential severity of injury or damage to health
(3) To determine if additional protective measures are required, including the use of PPE
130.5 (B) Estimate of Likelihood and Severity.
The estimate of the likelihood of occurrence of injury or damage to health and the potential severity of injury or damage to health shall take into consideration the following: a. The design of the electrical equipment, including its overcurrent protective device and its operating time b. The electrical equipment operating condition and condition of maintenance
130.5 (C) Additional Protective Measures . If additional protective measures are required they shall be selected and implemented according to the hierarchy of risk control identified in 110.1(H). When the additional protective measures include the use of PPE, the following shall be determined:
(1) Appropriate safety-related work practices
(2) The arc flash boundary
(3) The PPE to be used within the arc flash boundary
Table 130.5(C) shall be permitted to be used to estimate the likelihood of occurrence of an arc flash event to determine if additional protective measures are required.
- Table 130.5(C) Estimate of the Likelihood of Occurrence of an Arc Flash Incident for ac and dc Systems
Based on the following items:
- Task Being Performed
- Equipment Condition (Any, Normal, or Abnormal)
- Likelihood of Occurrence (Yes or No)
TABLE 130.5(C) Estimate of the Likelihood of Occurrence of an Arc Flash Incident for ac and dc Systems
- Where this table identifies “No” as an estimate of likelihood of occurrence, it means that an arc flash incident is not likely to occur.
- Where this table identifies “Yes” as an estimate of likelihood of occurrence, it means that additional protective measures are required to be selected and implemented according to the hierarchy of risk control identified in 110.1(H).

130.5(E)(2) The arc flash boundary shall be permitted to be determined by Table 130.7(C)(15)(a) or Table 130.7(C)(15)(b) when the requirements of these tables apply.
There are two methods that can be used in an arc flash risk assessment to determine the arc flash boundary.
- The incident energy analysis method, which results in an arc flash boundary at a distance where the incident energy is 1.2 cal/cm2.
- The other is the arc flash PPE category method, which results in an arc flash boundary selected directly from the tables in 130.7(C)(15)
130.5(F) Arc Flash PPE . One of the following methods shall be used for the selection of arc flash PPE:
(1) The incident energy analysis method in accordance with 130.5(G)
(2) The arc flash PPE category method in accordance with 130.7(C)(15)
Either, but not both, methods shall be permitted to be used on the same piece of equipment. The results of an incident energy analysis to specify an arc flash PPE category in Table 130.7(C)(15)(c) shall not be permitted
130.5(G) Incident Energy Analysis Method
The incident energy analysis shall take into consideration the characteristics of the overcurrent protective device and its fault clearing time, including its condition of maintenance.
The incident energy analysis shall be updated when changes occur in the electrical distribution system that could affect the results of the analysis. The incident energy analysis shall also be reviewed for accuracy at intervals not to exceed 5 years.
*Use Table 130.5(G) For PPE when using this method
Table 130.5(G) identifies the arc-rated clothing and other PPE requirements…and used with the incident energy analysis method of selecting arc flash PPE.
- No PPE specified for less than 1.2 cal/cm2
- PPE for 1.2 cal/cm2 to 12 cal/cm2
- PPE for greater than 12 cal/cm2
130.5(H) Equipment Labeling: Electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers that are in other than dwelling units and that are likely to require examination, adjustment, servicing, or maintenance while energized shall be marked with a label containing all the following information
(1) Nominal system voltage
(2) Arc flash boundary
(3) At least one of the following: a. Available incident energy and the corresponding working distance, or the arc flash PPE category in Table 130.7(C)(15)(a) or Table 130.7(C)(15)(b) for the equipment, but not both b. Minimum arc rating of clothing c. Site-specific level of PPE
The updated standard states that if the likelihood of an arc flash for a particular activity exists, employers can now use one of two methods to determine the appropriate PPE:
- Incident energy analysis method: Annex D and Table 130.5(G)
- Arc flash PPE category method: Table 130.5(C) and a series of tables in 130.7(C)(15)
Option 1 would be utilizing the ARC flash assessment methodology by hiring an engineering firm to come out and do the assessment. They can determine exactly what the equipment is capable of producing, so the customer knows the risks and the arc flash energy for each one.
Table 130.5(G), formerly part of the 70E Annex, has been revised and moved into the standard’s mandatory text.
Option 2 is using Tables 130.5(C) and 130.7(C)(15)(a and b), which lists Category 1 to Category 4, based on the maximum arc flash energy level, and identifies all of the PPE needed for each category. In order to use this method, a safety manager must know the maximum available fault current, maximum fault-clearing time and minimum working distances for each equipment type.
Calculate the two sets of arc duration, incident energy, and arc-flash boundary values based on the interpolation arcing current to account for the arcing current variation effect on the operation of protective devices. The final incident energy or arc-flash boundary is the higher of the two calculated values.
Article 130: Work Involving Electrical Hazards
As mentioned, an overarching theme of 2018 NFPA 70E stresses the hierarchy of risk controls. Updates reference de-energized work and, from an employer standpoint, there are a few important considerations to incorporate into energized work practices and procedures.
When de-energizing is infeasible or creates an additional hazard, working energized is an option and will require appropriate arc-rated PPE.
Section 130.5 provides new information regarding an arc flash risk assessment and includes new sections and tables to determine the likelihood of occurrence and the potential injury severity from an arc flash hazard. The Table 130.5 (C) uses a yes/no format to easily discern whether there is a likelihood of occurrence of an arc flash incident when working on certain tasks and equipment. An affirmative listing in the table leads to action requiring additional protective measures, which includes PPE use.
4.11 Single-phase systems
This model does not cover single-phase systems. Arc-flash incident energy testing for single-phase systems has not been researched with enough detail to determine a method for estimating the incident energy. Singlephase systems can be analyzed by using the single-phase bolted fault current to determine the single-phase arcing current (using the equations provided in 4.4 and 4.10
). The voltage of the single-phase system (line-toline, lineto-ground, center tap voltage, etc.) can be used to determine the arcing current. The arcing current can then be used to find the protective device opening time and incident energy by using the three-phase equations provided in this guide. The incident energy result is expected to be conservative.
4.12 DC systems
Arc-flash incident energy calculation for dc systems is not part of this model. However, publication references (Ammerman et al. [B1] , Das [B16] ,
[B17] , Doan B25] , Klement [B62] ) provide some guidance for incident energy calculation.