“Arc flash” hazards, incident energy, PPE ratings and thermal burn injury - A deeper look

Tremendous resources are being invested in arc flash studies and personal protective equipment (PPE) to protect workers from “arc flash” hazards. In the flurry to comply with OSHA regulations and NFPA 70 and 70E Standards, real understanding of the arc hazard and incident energy may be lagging behind. The term “arc flash” does not adequately convey the range of potential arc hazards - light, pressure and heat transmission, as well as others. The term “arc flash” also fails to emphasize that arc flash injuries primarily arise from thermal burns, and that the risk of a potentially severe or fatal arc burn is often present when performing electrical work. Worker risk assessment and the appropriate PPE are represented as definitive quantities in “cal/cm²;” however, the quantitative potential heat exposure and heat protection afforded by PPE are usually less precise than the assigned numerical value. Basic concepts of incident energy, PPE ratings and burn injury are also explored in this paper to help identify factors influencing the burn hazards posed by arcing faults in electrical power systems.