How accurate are your arc flash hazard study results

Abstract

The arc flash hazard study is normally implemented based on collection and application of considerable amount of data. The significance of each piece of data on the study results are not the same, so the possible errors in collection and application of such data would not have the same impact on the final calculated incident energy. Therefore the determination of erroneous areas and how they would affect the study results will give the study engineer a better recognition of the study results reliability and how to be concerned about the validity of input data. The existing arc flash incident energy exposure calculation methodologies presented in IEEE 1584-2002/2004 and NFPA 70E-2009 standards are based on a general approach requiring three major parameters. These well-known parameters are bolted or arcing fault current, arcing time duration, and minimum working distance from the arc location. The first two, bolted or arcing fault current and arc duration, are systematic parameters calculated from configuration and characteristics of the modeled electrical network. But the minimum working distance is a physical parameter that is defined based on the voltage, enclosure, and type of the implemented task on equipment. In this paper, the possible errors in these areas and their impacts on calculation of thermal exposure to incident energy are discussed and recommendations are made to increase the possibility of achieving more conservative results leading to safer working environment.