chapter  21
44 Pages

Arc Flash Hazard Analysis

WithJ.C. Das

Industrial electrical systems in the United States were designed considering prevalent standards, that is, American National Standards Institute/IEEE, National Electric Code, OSHA, UL, NESC, and the like, and arc flash hazard was not a direct consideration for the electrical system designs. This environment is changing fast, and the industry is heading toward innovations in the electrical systems designs, equipment, and protection to limit the arc flash hazard, as it is detrimental to the workers’ safety. If all maintenance work could be carried out in de-energized state, a short circuit cannot occur, and therefore there is no risk of arc flash hazard. Most commercially available programs analyze arc flash hazard as a subroutine to short-circuit calculations. Bolted short-circuit currents in various operating modes are required to be calculated, and the arc flash hazard calculated for a variation between 100% and 85% of arcing current in each scenario.