![]() ![]() 1Also, NFPA 70E 2states that “a second-degree burn is possible by an exposure of unprotected skin to an electric arc flash above the incident energy level of 1.2 cal/cm 2( 5.0 J/cm 2)” and assumes 1.2 cal/cm 2as a threshold incident energy level for a second-degree burn for systems 50 volts and greater. ![]() The incident energy of 1.2 cal/cm 2( 5.0 J/cm2) for bare skinwas selected in solving equation for the arc-flash boundary in IEEE P 1584. The incident energy to which the worker’s face and chest could be exposed at working distance during an electrical arc event was selected as a measure for determining hazard risk category and calculating arc-flash protection boundary. The IEEE P 1584 was developed by having incident energy testing performed based on methodology described in the ASTM F1959-99 standard. Use of Incident Energy as a Measure of Burn Severity in Arc-Flash Boundary Calculations ![]() The formulas are based on incident energy testing performed and calculations conducted for a selected range of prospective fault currents, system voltages, physical configurations, etc. Among others, the IEEE Standard P 1584 Guide for Performing Arc-Flash Hazard Calculations1 and formulas provided in Annex D of NFPA 70E2 and CSA Z462 Workplace Electrical Safety Standard are the most often utilized in the industry to perform arc-flash hazard analysis. During the last two decades different formulas have been proposed to calculate incident energy at an assumed working distance, and the arc-flash boundary in order to determine arc-rated personal protective equipment for qualified electrical workers. Our interest in determining accurate onset to second-degree burn energy and its significance in computing the arc-flash boundary is focused on the prevention of injury to the skin of a human who might be exposed to an arc flash. ![]()
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