Arc Flash Calculator

Compute incident energy and arc-flash boundary per IEEE 1584-2018. All calculations run client-side — no data leaves your device.

Power system
System-level electrical parameters at the fault location.
Protection
Clearing time read from the protective device TCC curve.

≈ 0.200 s · @ 60 Hz

≈ 0.200 s · @ 60 Hz

Reduced is usually longer (lower current → slower protective device). The worst case is auto-selected for PPE classification.
Geometry & configuration
Physical layout of the equipment and the worker position.

Default for selected voltage (IEEE 1584-2018 Table A.1).

L1
L2
L3
VCB — Vertical Conductors in Box

Vertical conductors terminate open inside a metal enclosure. The 3-phase supply enters from the top. The arc forms at the lower end and the plasma cloud is directed forward through the enclosure opening. Common in LV switchgear, MCCs and fuse cabinets.

Required for in-box configurations so the enclosure correction factor can be computed (IEEE 1584-2018 Eqs. 11–15).

Results
Fill in the form and click Calculate to see incident energy, arc-flash boundary and PPE category.
About

What this tool does

This tool performs arc-flash incident-energy and arc-flash-boundary calculations according to IEEE 1584-2018, the industry standard for arc-flash hazard analysis. The empirical model is used for three-phase systems from 208 V up to 15 kV; the Lee method serves as a conservative fallback above 15 kV. Both the max (full arcing current) and reduced (current with VarCF correction) scenarios are computed and the worst case is reported, per the standard's recommendation. PPE category classification follows NFPA 70E-2024 Table 130.5(G).

Disclaimer

This tool is for engineering analysis assistance only. Results should be verified by a qualified engineer before being used for safety-critical decisions. The author assumes no liability for misuse.

About the author

Built by Ali Iguider, an MV/LV systems engineer — connect on LinkedIn.