Sustainability of an Electric Arc Flash at a Voltage of 240 Vac and 150 Vdc

The purpose of this paper is to present arc flash laboratory results related to the occurrence of an electric arc flash and the protection offered to workers during arc flash event. The goal was to carry out laboratory tests in order to evaluate the sustainability of an electric arc flash at a single phase voltage of 240 Vac, and the adequacy of the choice of the formula for evaluating the incident energy at 150 Vdc compared to the values obtained in the laboratory. For alternating current, there is a discrepancy according to the applicable standard for the same task. This discrepancy results in the application of different safety measures. Preliminary research tends to support the thesis of a non-sustainability of the electric arc flash at 240 Vac, whereas the use of the formula employed for the direct current would be far too conservative compared to laboratory tests. Following confirmation of the preliminary results, it would be possible to review the protection required during high-risk dc tasks and to rule on the dangerousness of several activities. Doing so could eliminate the need to wear PPE, or reduce the necessary protection associated with risky procedures.