Calculates the incident energy, arc flash boundary and required PPE category for a point in an electrical system — the core hazard analysis behind arc-flash warning labels and safe-work-distance/PPE decisions for live or potentially-live electrical work.
Standards followed
IEEE 1584-2002 (empirical arc-flash hazard model)IEEE 1584-2018 (current edition — full model)Ralph Lee theoretical model (Lee, 1982)
What it can do
- IEEE 1584-2002 empirical model — arcing current, incident energy, arc flash boundary and PPE category from equipment class, enclosure, gap and grounding.
- Ralph Lee theoretical model — no equipment class or gap needed, works at any voltage, generally more conservative and used as the fallback above 15kV.
- Out-of-range warnings when inputs fall outside the IEEE 1584-2002 validated range (0.7-106kA, 0.208-15kV).
- Advanced: IEEE 1584-2018, the current edition, with electrode configuration and enclosure size correction.
Example problem
A 415V LV MCC with a 25kA bolted fault current, 455mm working distance and a 0.2s clearing time. Estimate the incident energy using IEEE 1584-2002.
- Look up typical gap (G) and distance exponent (x) for the LV MCC equipment class.
- Compute arcing current Ia from bolted fault current, voltage, gap and enclosure type.
- Compute normalized incident energy En from Ia, gap, enclosure and grounding.
- Scale En by voltage, time and working distance to get incident energy E, and compute the arc flash boundary from the same normalized energy.
The resulting incident energy determines the PPE category (from a standard cal/cm² table) and the arc flash boundary defines the distance at which incident energy drops to the 1.2 cal/cm² onset-of-second-degree-burn threshold.
Want the full step-by-step version?
PPE category note: NFPA 70E uses PPE categories with its table method; when incident energy is calculated, select arc-rated clothing with an arc rating at least equal to the incident energy, and label equipment with either the incident energy or the PPE category, not both (NFPA 70E 130.5(H)). The category shown here is an indicative mapping of the energy to the 4/8/25/40 cal/cm\u00b2 clothing levels. IEEE 1584-2002 has separate arcing-current equations for systems up to 1kV and for 1-15kV; this calculator uses each in its own range (applying the low-voltage equation above 1kV gives non-physical arcing currents larger than the bolted fault current).