Predicting incident energy to better manage the electric arc hazard on 600-V power distribution systems

A test program has been completed to measure incident energy from 6-cycle arcs on 600 V three-phase electric power distribution systems. Testing was performed using an arc electrode gap of 1.25 in that had previously produced maximum incident energy for a 600 V power system with a 36.25 kA prospective fault current. The effect on incident energy of enclosing the arcs in a cubic box was determined. Simple algorithms were developed to allow estimation of incident energy at a specified distance from arc electrodes as a function of the available bolted fault current on a 600 V electric power distribution system. A comparison is made with previously published methods for estimating incident energy and safe approach distances. The impact of the estimating algorithm on the management of the electric arc hazard is discussed.