Arc Flash Incident Energy & Boundary Calculator
Determine incident energy exposure (cal/cm²), arc flash boundary distance (AFB), and required NFPA 70E PPE category per IEEE 1584-2018 standards.
Electrical System & Fault Parameters
IEEE 1584 Configuration & Enclosure
Arc Flash Exposure & PPE Sizing
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Frequently Asked Questions
What is incident energy in arc flash calculations?
Incident energy is the amount of thermal energy impressed on a surface at a specified working distance from an electric arc, expressed in calories per square centimeter (cal/cm²) or Joules per square centimeter (J/cm²). A second-degree burn threshold occurs at 1.2 cal/cm² (5.0 J/cm²).
Why does HCB (Horizontal Conductors in Box) produce more incident energy than VCB?
In the IEEE 1584-2018 model, HCB configuration features horizontal bus stabs pointing directly toward the enclosure door. The electromagnetic Lorentz forces shoot the plasma arc and copper fireball directly outward toward the worker, yielding up to 60-70% higher incident energy than vertical conductors.
How does clearing time impact arc flash risk more than bolted fault current?
Incident energy scales linearly with clearing time (t), whereas higher fault currents often trigger instantaneous breaker magnetic trips faster, paradoxically lowering total energy. A moderate fault current that falls into the long-time or short-time delay region of a trip unit can yield catastrophic arc energy due to prolonged arc duration.