Low Voltage ARC Sustainability

Arc Flash in low voltage equipment (480 volts and below) is a safety issue that can impact work practices for electrical workers. When estimating incident energy for low voltage equipment, the duration of the arc is typically the driving factor. This paper summarizes previous testing results that establish arc sustainability for various equipment configurations, when trip devices do not operate. In some cases, arc duration is limited by the physical conditions of the enclosure and by the driving voltage and current available. Using the maximum duration for arc sustainability can provide more realistic estimated incident energies than using the two-second self-extraction time cited in IEEE 1584-2002. Consequently, required levels of personal protective equipment can be reduced while still providing adequate protection to the worker.