Electric arcing burn hazards

The paper presents recent results in the area of high power testing aimed at improving the safety of electrical staff working on live equipment. The driver for this work is the American guide (IEEE 1584) on such exposure hazards, which has the potential for international adoption and, in the authors´ opinion, does not provide a suitable methodology for assessing the hazard. A selection of results are presented, obtained in a high-power-system supplied commercial test laboratory, using the latest CCD based high-speed video recording methods. Results are reported for 415 V currents in the range 1,000 to 70,000 prospective rms amperes and for tests at 5,000 V in the range 1,000 to 27,000 A. Video results for the nature and evolution of the three-phase open-air arc is shown for practical switchboards. The impact of conventional protective devices is included together with some disturbing video results for circuit breaker protected systems. The presentation includes CD based video sequences, which emphasises the violent impact of these explosive events. The major part of the material in this paper was first published at the 7th International Conference on Electric Fuses and their Applications [Stokes, AD et al., 2003].