Estimate incident energy (cal/cm²) and PPE category using the IEEE 1584-2018 Lee Method. For preliminary hazard screening — full study requires Professional plan.
IEEE 1584-2018 Lee Method — E = (793 × V_kV × I²_a × t) / D²
Enter system parameters and press Calculate
NFPA 70E-2021 Table 130.5(G) defines four PPE categories based on incident energy levels. Each category specifies minimum arc-rated clothing and PPE requirements.
| PPE Cat. | Incident Energy | Min Arc Rating |
|---|---|---|
| Category 1 | ≤ 1.2 cal/cm² | 4 cal/cm² AR |
| Category 2 | 1.2–12 cal/cm² | 8 cal/cm² AR |
| Category 3 | 12–25 cal/cm² | 25 cal/cm² AR |
| Category 4 | 25–40 cal/cm² | 40 cal/cm² AR |
| Danger Zone | > 40 cal/cm² | Do not work energized |
E = (793 × VkV × Ia² × t) / D²
Where E = incident energy (cal/cm²), VkV = system voltage (kV), Ia = arcing current (kA), t = arc duration (seconds), D = working distance (inches).
NEC 110.16 requires arc flash warning labels on all electrical equipment likely to require examination, adjustment, servicing, or maintenance while energized. Labels must warn of arc flash hazard but do not need to specify incident energy.
Professional plan includes the complete empirical model study, arc flash boundary calculation, equipment-specific label generation, and a compliant engineering report.
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