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Arc Flash Study (IEEE 1584-2018) — Network, Labels & PPE

Build the network once and get the arc-flash incident energy, boundary, PPE category and warning label for every bus. Fault currents come from the IEC 60909 short-circuit model, the arc duration from the protective device you describe, and the arc-flash result from the full IEEE 1584-2018 model (208 V – 15 kV) at both maximum and minimum fault current, including the reduced-arcing-current check. Includes a colour-coded single-line diagram, boundary and energy graphs, a what-if for faster clearing, printable NFPA 70E style labels and the step-by-step calculation.

AAJappsEngineering Calculation Report

Arc Flash Study (IEEE 1584-2018)

IEEE 1584-2018 · IEC 60909-0 · NFPA 70E reference tables

Generated

For preliminary engineering use only — always verify results against project-specific standards and a qualified engineer's review before use in a real design.

Projects & scenarios

Saved in this browser — export a file to back up or move devices

No saved scenarios yet. Build a network, give it a name and press “Save as new”.

Single-line diagram — incident energy by bus

Click a bus to inspect it below

Highest incident energy: 0.4 kV LV Board at 21.2 cal/cm² (PPE Category 3), boundary 3.68 m.

T1 11/0.4 kV1.60 MVA · 6.0 % · DynCable to MCC50 mUtility incomer250 MVAGGen G12.50 MVA11 kV Switchboard · 11.0 kVE = 4.7 cal/cm²AFB 2182 mm @ 914 mmPPE Cat 2 · Ibf 14.2 kA0.4 kV LV Board · 0.40 kVE = 21.2 cal/cm²AFB 3676 mm @ 610 mmPPE Cat 3 · Ibf 39.7 kAMMotor M1160 kWMotor Control Centre · 0.40 kVE = 2.5 cal/cm²AFB 730 mm @ 457 mmPPE Cat 1 · Ibf 23.0 kA
< 1.2 cal/cm² (Cat 0)≤ 4 (Cat 1)≤ 8 (Cat 2)≤ 25 (Cat 3)≤ 40 (Cat 4)> 40 — DANGER

Arc-flash results at every bus

BusVoc (kV)Ibf max / min (kA)Iarc (kA)Arc time (ms)E (cal/cm²)AFB (mm)Work dist (mm)PPEWith maintenance modeClear in ≤ (ms) for 8 cal/cm²
11 kV Switchboard11.014.2 / 14.112.93004.72182914Cat 2–met
0.4 kV LV Board0.40039.7 / 37.923.852621.23676610Cat 32.0 (50 ms)199
Motor Control Centre0.40023.0 / 20.316.01002.5730457Cat 1–met

E is the higher of the average-arcing-current and reduced-arcing-current cases, at the worse of the maximum and minimum fault current. Arc time is the protective-device clearing time at the governing arcing current. Select a row for graphs and the label.

Ranking

0.4 kV LV Board
21.2 cal/cm²
11 kV Switchboard
4.7 cal/cm²
Motor Control Centre
2.5 cal/cm²

Vertical lines mark 8, 25 and 40 cal/cm² (PPE Category 2, 3 and 4 limits).

Detail — 11 kV Switchboard

Approach and arc-flash boundaries

11 kV Swi…WArc-flash boundary 2.18 mLimited approach 1.50 mRestricted approach 0.66 mWorking distance 0.91 m

Incident energy against working distance

0.512510205030572411431562198124001.2 (boundary)4 (Cat 1)8 (Cat 2)25 (Cat 3)40 (Cat 4)4.7 at 914 mmWorking distance (mm)Incident energy (cal/cm²)

Incident energy against total clearing time

0.51251020502021641260880410001.2 (boundary)4 (Cat 1)8 (Cat 2)25 (Cat 3)40 (Cat 4)now: 4.7 @ 300 msTotal arc clearing time (ms)Incident energy (cal/cm²)

The incident energy is already at or below 8 cal/cm² (Category 2).

PPE Category 2

Category 1 clothing at the higher rating, with arc-rated balaclava and face shield or arc flash suit hood.

Arc-flash warning labels

One label per bus, in the NFPA 70E / ANSI Z535 style. Print on adhesive label stock and attach to the equipment. Re-print after any change to the system.

WARNING
Arc Flash and Shock Hazard — appropriate PPE required
11 kV Switchboard · 11.0 kV · 15 kV switchgear
Arc flash hazard
Incident energy: 4.7 cal/cm²
at working distance 914 mm (36 in)
Arc-flash boundary: 2182 mm (7 ft 2 in)
Required PPE
PPE Category 2
Minimum arc rating 8 cal/cm²
Shock hazard (AC)
Nominal voltage 11000 V · Limited approach 1.5 m (4 ft 11 in) · Restricted approach 0.66 m (2 ft 2 in)
Upstream device: clears in 300 ms · Gap 152 mm · VCB · Study date ________ · IEEE 1584-2018 · Verify before work
WARNING
Arc Flash and Shock Hazard — appropriate PPE required
0.4 kV LV Board · 0.400 kV · Low-voltage switchgear
Arc flash hazard
Incident energy: 21.2 cal/cm²
at working distance 610 mm (24 in)
Arc-flash boundary: 3676 mm (12 ft 1 in)
Required PPE
PPE Category 3
Minimum arc rating 25 cal/cm²
Shock hazard (AC)
Nominal voltage 400 V · Limited approach 1.0 m (3 ft 3 in) · Restricted approach 0.30 m (1 ft 0 in)
Upstream device: IEC SI relay, pickup 100 A, TMS 0.15 · Gap 32 mm · VCB · Study date ________ · IEEE 1584-2018 · Verify before work
WARNING
Arc Flash and Shock Hazard — appropriate PPE required
Motor Control Centre · 0.400 kV · Shallow LV MCC / panelboard (≤ 203 mm deep)
Arc flash hazard
Incident energy: 2.5 cal/cm²
at working distance 457 mm (18 in)
Arc-flash boundary: 730 mm (2 ft 5 in)
Required PPE
PPE Category 1
Minimum arc rating 4 cal/cm²
Shock hazard (AC)
Nominal voltage 400 V · Limited approach 1.0 m (3 ft 3 in) · Restricted approach 0.30 m (1 ft 0 in)
Upstream device: clears in 100 ms · Gap 25 mm · VCB · Study date ________ · IEEE 1584-2018 · Verify before work

1 · Network (short-circuit model)

The same editor as the IEC 60909 calculator. Add buses, sources, transformers, cables and ties; the diagram and fault levels follow.

Build your network

Add or edit anything below — the diagram and tables above update immediately. Use “Apply typical values…” on any item to start from a realistic set of constants.

Study settings

s
s

Buses

Each bus is a busbar at one nominal voltage. Sources and branches attach to buses.

kV
kA
kV
kA
kV
kA

Sources — utility, generators, motors

Any number per bus. Generators and the utility feed the fault; motors add to the maximum fault current only.

GridUtility incomer
MVA
GeneratorGen G1
MVA
kV
%
%
Ω
MotorMotor M1
kW
kV

Branches — transformers, cables, bus ties

Each branch joins two buses. For a transformer, the ‘from’ bus is the first-listed winding side (HV side by convention).

TransformerT1 11/0.4 kV
MVA
%
kW
Ω
Ω
Cable / lineCable to MCC
Ω/km
Ω/km
Ω/km
Ω/km
km

2 · Arc-flash data and protection for each bus

Equipment class, electrode configuration, enclosure, working distance, and the device that clears an arcing fault.

Study settings

ms

11 kV Switchboard (11 kV)

Arc-flash data for this bus
mm
mm
mm
mm
mm

Protective device that clears an arc at this bus

ms

Mitigation what-if

ms

0.4 kV LV Board (0.4 kV)

Arc-flash data for this bus
mm
mm
mm
mm
mm

Protective device that clears an arc at this bus

kV
A
A
ms
ms

Mitigation what-if

ms

Motor Control Centre (0.4 kV)

Arc-flash data for this bus
mm
mm
mm
mm
mm

Protective device that clears an arc at this bus

ms

Mitigation what-if

ms

Step-by-step manual calculation (IEEE 1584-2018)

Each bus lists the inputs, intermediate values and final results so the study can be checked by hand against the equations of clause 4. The fault current itself comes from the IEC 60909 working on the Short Circuit page.

11 kV Switchboard (11.0 kV · 15 kV switchgear · VCB · gap 152 mm)

4.70 cal/cm²
  1. Fault current from the short-circuit study: maximum Ibf = 14.20 kA, minimum Ibf = 14.13 kA (referred to nominal voltage, c = 1).
  2. — Maximum fault current (Ibf = 14.20 kA) —
  3. Inputs: Voc = 11.000 kV, Ibf = 14.20 kA, gap G = 152.0 mm, working distance D = 914.4 mm, configuration VCB, enclosure 1143 × 762 × 762 mm (H×W×D).
  4. Enclosure correction (4.8): Typical enclosure; Width1 = 29.000 in, Height1 = 45.000 in, EES = (H1+W1)/2 = 37.000; CF = b1·EES²+b2·EES+b3 = 1.292.
  5. Intermediate arcing currents, Eq (1): Iarc_600 = 10.193 kA, Iarc_2700 = 12.034 kA, Iarc_14300 = 13.310 kA.
  6. Interpolated to Voc = 11.000 kV, Eqs (16)–(18): Iarc = 12.947 kA.
  7. Arc duration from the protective device at Iarc: T = 300 ms.
  8. Intermediate incident energy, Eqs (3)–(5): E600 = 13.651, E2700 = 18.017, E14300 = 20.124 J/cm²; interpolated (Eqs 19–21) E = 19.524 J/cm² = 4.666 cal/cm².
  9. Intermediate arc-flash boundary, Eqs (7)–(9): 1710, 2064, 2216 mm; interpolated (Eqs 22–24) AFB = 2173 mm.
  10. Arcing-current variation, Eq (2): VarCf = 0.0253; reduction factor (1 − 0.5·VarCf) = 0.9874.
  11. Reduced arcing current Iarc_min = 12.784 kA → arc duration 300 ms → E = 19.653 J/cm² = 4.697 cal/cm², AFB = 2182 mm.
  12. Final result = the higher of the two: E = 4.70 cal/cm² (19.65 J/cm², reduced arcing current), AFB = 2182 mm (boundary at 1.2 cal/cm² = 5.0 J/cm²). 1 cal = 4.184 J.
  13. — Minimum fault current (Ibf = 14.13 kA) —
  14. Inputs: Voc = 11.000 kV, Ibf = 14.13 kA, gap G = 152.0 mm, working distance D = 914.4 mm, configuration VCB, enclosure 1143 × 762 × 762 mm (H×W×D).
  15. Enclosure correction (4.8): Typical enclosure; Width1 = 29.000 in, Height1 = 45.000 in, EES = (H1+W1)/2 = 37.000; CF = b1·EES²+b2·EES+b3 = 1.292.
  16. Intermediate arcing currents, Eq (1): Iarc_600 = 10.148 kA, Iarc_2700 = 11.983 kA, Iarc_14300 = 13.253 kA.
  17. Interpolated to Voc = 11.000 kV, Eqs (16)–(18): Iarc = 12.892 kA.
  18. Arc duration from the protective device at Iarc: T = 300 ms.
  19. Intermediate incident energy, Eqs (3)–(5): E600 = 13.588, E2700 = 17.942, E14300 = 20.041 J/cm²; interpolated (Eqs 19–21) E = 19.444 J/cm² = 4.647 cal/cm².
  20. Intermediate arc-flash boundary, Eqs (7)–(9): 1705, 2059, 2211 mm; interpolated (Eqs 22–24) AFB = 2167 mm.
  21. Arcing-current variation, Eq (2): VarCf = 0.0253; reduction factor (1 − 0.5·VarCf) = 0.9874.
  22. Reduced arcing current Iarc_min = 12.729 kA → arc duration 300 ms → E = 19.571 J/cm² = 4.678 cal/cm², AFB = 2176 mm.
  23. Final result = the higher of the two: E = 4.68 cal/cm² (19.57 J/cm², reduced arcing current), AFB = 2176 mm (boundary at 1.2 cal/cm² = 5.0 J/cm²). 1 cal = 4.184 J.
  24. Governing case: Maximum fault current, E = 4.70 cal/cm² at 914 mm → Below 1.2 cal/cm².

0.4 kV LV Board (0.400 kV · Low-voltage switchgear · VCB · gap 32 mm)

21.19 cal/cm²
  1. Fault current from the short-circuit study: maximum Ibf = 39.67 kA, minimum Ibf = 37.87 kA (referred to nominal voltage, c = 1).
  2. — Maximum fault current (Ibf = 39.67 kA) —
  3. Inputs: Voc = 0.400 kV, Ibf = 39.67 kA, gap G = 32.0 mm, working distance D = 609.6 mm, configuration VCB, enclosure 508 × 508 × 508 mm (H×W×D).
  4. Enclosure correction (4.8): Typical enclosure; Width1 = 20.000 in, Height1 = 20.000 in, EES = (H1+W1)/2 = 20.000; CF = b1·EES²+b2·EES+b3 = 1.000.
  5. Arcing current at 600 V, Eq (1): Iarc_600 = 29.646 kA; final arcing current at 0.400 kV, Eq (25): Iarc = 23.798 kA.
  6. Arc duration from the protective device at Iarc: T = 526 ms.
  7. Incident energy, Eq (6): E = 88.655 J/cm² = 21.189 cal/cm²; arc-flash boundary, Eq (10): AFB = 3676 mm.
  8. Arcing-current variation, Eq (2): VarCf = 0.2551; reduction factor (1 − 0.5·VarCf) = 0.8724.
  9. Reduced arcing current Iarc_min = 20.762 kA → arc duration 559 ms → E = 82.657 J/cm² = 19.756 cal/cm², AFB = 3518 mm.
  10. Final result = the higher of the two: E = 21.19 cal/cm² (88.66 J/cm², average arcing current), AFB = 3676 mm (boundary at 1.2 cal/cm² = 5.0 J/cm²). 1 cal = 4.184 J.
  11. — Minimum fault current (Ibf = 37.87 kA) —
  12. Inputs: Voc = 0.400 kV, Ibf = 37.87 kA, gap G = 32.0 mm, working distance D = 609.6 mm, configuration VCB, enclosure 508 × 508 × 508 mm (H×W×D).
  13. Enclosure correction (4.8): Typical enclosure; Width1 = 20.000 in, Height1 = 20.000 in, EES = (H1+W1)/2 = 20.000; CF = b1·EES²+b2·EES+b3 = 1.000.
  14. Arcing current at 600 V, Eq (1): Iarc_600 = 28.620 kA; final arcing current at 0.400 kV, Eq (25): Iarc = 23.091 kA.
  15. Arc duration from the protective device at Iarc: T = 533 ms.
  16. Incident energy, Eq (6): E = 86.822 J/cm² = 20.751 cal/cm²; arc-flash boundary, Eq (10): AFB = 3628 mm.
  17. Arcing-current variation, Eq (2): VarCf = 0.2551; reduction factor (1 − 0.5·VarCf) = 0.8724.
  18. Reduced arcing current Iarc_min = 20.146 kA → arc duration 567 ms → E = 81.026 J/cm² = 19.366 cal/cm², AFB = 3475 mm.
  19. Final result = the higher of the two: E = 20.75 cal/cm² (86.82 J/cm², average arcing current), AFB = 3628 mm (boundary at 1.2 cal/cm² = 5.0 J/cm²). 1 cal = 4.184 J.
  20. Governing case: Maximum fault current, E = 21.19 cal/cm² at 610 mm → Below 1.2 cal/cm².

Motor Control Centre (0.400 kV · Shallow LV MCC / panelboard (≤ 203 mm deep) · VCB · gap 25 mm)

2.54 cal/cm²
  1. Fault current from the short-circuit study: maximum Ibf = 22.97 kA, minimum Ibf = 20.27 kA (referred to nominal voltage, c = 1).
  2. — Maximum fault current (Ibf = 22.97 kA) —
  3. Inputs: Voc = 0.400 kV, Ibf = 22.97 kA, gap G = 25.0 mm, working distance D = 457.2 mm, configuration VCB, enclosure 356 × 305 × 203 mm (H×W×D).
  4. Enclosure correction (4.8): Shallow enclosure; Width1 = 12.000 in, Height1 = 14.000 in, EES = (H1+W1)/2 = 13.000; CF = 1/(b1·EES²+b2·EES+b3) = 1.503.
  5. Arcing current at 600 V, Eq (1): Iarc_600 = 18.945 kA; final arcing current at 0.400 kV, Eq (25): Iarc = 16.015 kA.
  6. Arc duration from the protective device at Iarc: T = 100 ms.
  7. Incident energy, Eq (6): E = 10.614 J/cm² = 2.537 cal/cm²; arc-flash boundary, Eq (10): AFB = 730 mm.
  8. Arcing-current variation, Eq (2): VarCf = 0.2551; reduction factor (1 − 0.5·VarCf) = 0.8724.
  9. Reduced arcing current Iarc_min = 13.972 kA → arc duration 100 ms → E = 9.314 J/cm² = 2.226 cal/cm², AFB = 673 mm.
  10. Final result = the higher of the two: E = 2.54 cal/cm² (10.61 J/cm², average arcing current), AFB = 730 mm (boundary at 1.2 cal/cm² = 5.0 J/cm²). 1 cal = 4.184 J.
  11. — Minimum fault current (Ibf = 20.27 kA) —
  12. Inputs: Voc = 0.400 kV, Ibf = 20.27 kA, gap G = 25.0 mm, working distance D = 457.2 mm, configuration VCB, enclosure 356 × 305 × 203 mm (H×W×D).
  13. Enclosure correction (4.8): Shallow enclosure; Width1 = 12.000 in, Height1 = 14.000 in, EES = (H1+W1)/2 = 13.000; CF = 1/(b1·EES²+b2·EES+b3) = 1.503.
  14. Arcing current at 600 V, Eq (1): Iarc_600 = 16.823 kA; final arcing current at 0.400 kV, Eq (25): Iarc = 14.275 kA.
  15. Arc duration from the protective device at Iarc: T = 100 ms.
  16. Incident energy, Eq (6): E = 9.379 J/cm² = 2.242 cal/cm²; arc-flash boundary, Eq (10): AFB = 676 mm.
  17. Arcing-current variation, Eq (2): VarCf = 0.2551; reduction factor (1 − 0.5·VarCf) = 0.8724.
  18. Reduced arcing current Iarc_min = 12.454 kA → arc duration 100 ms → E = 8.230 J/cm² = 1.967 cal/cm², AFB = 623 mm.
  19. Final result = the higher of the two: E = 2.24 cal/cm² (9.38 J/cm², average arcing current), AFB = 676 mm (boundary at 1.2 cal/cm² = 5.0 J/cm²). 1 cal = 4.184 J.
  20. Governing case: Maximum fault current, E = 2.54 cal/cm² at 457 mm → Below 1.2 cal/cm².

Typical values and reference tables

Equipment classes (IEEE 1584-2018 Tables 8 and 10)

EquipmentGap (mm)Enclosure H × W × D (mm)Working distance (mm)
15 kV switchgear1521143 × 762 × 762914.4
15 kV MCC152914.4 × 914.4 × 914.4914.4
5 kV switchgear104914.4 × 914.4 × 914.4914.4
5 kV MCC104660.4 × 660.4 × 660.4914.4
Low-voltage switchgear32508 × 508 × 508609.6
Shallow LV MCC / panelboard (≤ 203 mm deep)25355.6 × 304.8 × 203.2457.2
Deep LV MCC / panelboard (> 203 mm deep)25355.6 × 304.8 × 254457.2
Cable junction box13355.6 × 304.8 × 203.2457.2

Electrode configurations

  • VCB — vertical electrodes in a metal box (enclosure). Typical switchgear, MCC and panelboard bus: vertical conductors terminating in an insulating barrier-free box. The usual worst-case choice.
  • VCBB — vertical electrodes, insulating barrier, in a box. Vertical conductors ending at an insulating barrier (e.g. breaker stabs, molded-case terminals).
  • HCB — horizontal electrodes in a box. Horizontal conductors in a box (e.g. horizontal bus, some switchboards and cable compartments).
  • VOA — vertical electrodes in open air. Vertical conductors with no enclosure (open busbars, overhead/outdoor).
  • HOA — horizontal electrodes in open air. Horizontal conductors with no enclosure.

PPE categories (NFPA 70E reference)

  • Category 1 — up to 4 cal/cm²: arc-rated shirt and pants, face shield with balaclava, hard hat, gloves, leather shoes.
  • Category 2 — up to 8 cal/cm²: as Category 1 at the higher rating, arc-rated balaclava and face shield or hood.
  • Category 3 — up to 25 cal/cm²: arc flash suit with hood, arc-rated gloves.
  • Category 4 — up to 40 cal/cm²: multi-layer arc flash suit with hood and gloves.
  • Above 40 cal/cm²: no standard PPE is adequate — reduce the energy or de-energize.