Arc Flash Calculator
Estimate arc flash incident energy, flash boundary, PPE category, and required cal rating per IEEE 1584.
Inputs
A
in
NFPA 70E / IEEE 1584: switchgear 91 cm; MCC/panels 46 cm; open bus/switch 91–183 cm
seconds
IEEE 1584: current-limiting fuse 0.008–0.017 s; electronic trip CB 0.05–0.1 s; thermal-mag CB 0.1–0.5 s
V
mm
Results
Incident Energy
15.84 cal/cm²
PPE Category
3
Arc Flash Boundary2,216 mm
Required Cal Rating25 cal/cm²
How to Use This Calculator
- Enter the Bolted Fault Current in amperes — obtain this from a short-circuit study or the utility's available fault current at the service entrance.
- Enter the Working Distance in cm from the potential arc source to the worker's face: switchgear ≈ 91 cm, MCC/panel ≈ 46 cm.
- Enter the Arc Duration in seconds — this is the clearing time of the upstream protective device (breaker trip time or fuse melt time).
- Enter the System Voltage in volts and the Gap Between Conductors in mm: LV switchgear ≈ 32 mm, MCC ≈ 25 mm.
- Read the Incident Energy in cal/cm² and the PPE Category (0–4) per NFPA 70E to select appropriate arc-rated PPE.
- Note the Arc Flash Boundary in mm — workers within this distance must wear full arc-rated PPE; beyond it, only basic protection is required.
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