Abstract: In order to further study the effect of thermal radiation on short circuit types and combustion behavior in electrical fire, the experimental circuit of thermal radiation induced short circuit fault on BVVB sheath cables was built. The short fault and combustion behaviors on energized cables exposed to different heat fluxes were observed. The results show that the probability of physical short is higher than that of arcing short when the heat flux is 27, 30, 32 kW/m2. When the heat flux is 30 kW/m2, the probability of physical short is highest, which is up to 100%. When the heat flux is 34, 36 kW/m2, the probability of arcing short is higher than that of physical short, the highest of which is up to 80%. The arc energy is between 200.22 J and 240.03 J when the physical short arc is produced and the combustion probability of physical short is 30.8%. However, the arc energy is 511.34~2 542.04 J when the arcing short is produced, the probability of ignition after short circuit is 100%. Conspicuously, arcing short is of greater fire danger. The research results can provide data support for tracing the root cause of electrical fire.

Key words: electrical fire, thermal radiation, BVVB sheath wire, physical short, arcing short