Frequently Asked Questions
What is the difference between IEEE 1584-2018 and the 2002 edition?
The 2018 edition introduced a new empirical model based on 2,000+ tests across five electrode configurations. It replaced the single-equation 2002 model with separate regression equations for each configuration (VCB, VCBB, HCB, VOA, HOA), resulting in more accurate incident energy estimates — sometimes significantly lower than the 2002 model.
What is incident energy?
Incident energy is the thermal energy density (cal/cm²) at the worker's face and body during an arc flash event. IEEE 1584-2018 calculates it at a specified working distance. 1.2 cal/cm² is the onset of second-degree burns on unprotected skin.
What does the arc flash boundary mean?
The arc flash boundary (AFB) is the distance from the arcing source at which the incident energy equals 1.2 cal/cm² — the onset of second-degree burns. Workers inside the AFB must wear appropriate PPE.
What PPE category is required?
NFPA 70E Table 130.7(C)(15)(c) defines four PPE categories: Cat 1 (1.2–4 cal/cm², minimum arc-rated face shield), Cat 2 (4–8 cal/cm², arc-rated balaclava), Cat 3 (8–25 cal/cm², arc flash suit), Cat 4 (25–40 cal/cm², higher-rated suit). Above 40 cal/cm², energized work is prohibited.
What is the 85% reduced arcing current?
Per §4.4, the arcing current may be as low as 85% of the calculated value for systems ≤600 V. This lower current may operate the protective device in a higher time-delay region, potentially resulting in higher incident energy. Both I_arc and I_arc,min must be evaluated.
Is this calculator suitable for a formal arc flash study?
This tool implements the IEEE 1584-2018 equations faithfully and is suitable for preliminary screening and educational use. A formal arc flash hazard analysis per NFPA 70E requires a licensed electrical engineer, verified one-line diagrams, accurate TCC curves, and a complete protective device coordination study.