Effect of insulating barriers in arc flash testing

Low-voltage arc flash testing has been conducted using the standard IEEE 1584 test procedure but modified so that the electrode tips are terminated in an insulating barrier instead of in the open air. The barrier prevents downward arc motion, has a stabilizing effect on the arcs, and produces a strong horizontal plasma cloud flow. It also produces shorter arc lengths, higher arcing currents and higher maximum incident energy density, when compared with the standard arrangement presently used. The erosion of the copper electrodes is much higher when a barrier is used, which causes a much larger quantity of copper spray to be directed toward the outside of the box. Similar results can be observed when vertical conductors are terminated in real industrial components. The effect of the barrier and the source X/R on arc sustainability at 208 V has also been studied. The barrier test arrangement is believed to be more representative of real-world equipment. It is proposed that an arrangement like this should be incorporated into future revisions of the IEEE 1584 testing standard.