Effect of Various Radiant Heat Fluxes on the Types and Characteristics of Short Circuit on Residential Electrical Cables

In this study, the effects of the possibility, time, and type of short circuits on energized residential electrical cables exposed to various radiant heat fluxes were investigated. Ten heat fluxes in the range of 21–30 kW/m² were used on the surfaces of cables to irradiate them at 220 VAC using a standard cone heater, as is widely used in China. Breakdown was likely to occur on a cable heated at as low as 22 kW/m². Electrical failure inevitably occurred at over 26 kW/m². When the heat flux increased to 30 kW/m², the maximum and average time required for breakdown decreased to 218 and 175.9 s, respectively. Below 26 kW/m², the probability of a physical short occurring was higher than that of an arcing short with more than one arc, which had greater ignitability. In contrast, this trend reversed above 26 kW/m². The arc number and duration of arcing shorts on cables exposed to heat flux below 26 kW/m² were less than that on cables exposed to heat fluxes over this value. In most cases, the increasing duration of an arcing short could lead to more arc beads. Consequently, with an increase in heat flux, common cables could generate an arcing short with more arc beads in less time.