Experimental study of flame spread overPE-insulated single copper core wire under varying pressure and electric current

In this study, the flame spread over a thin wire with overload current (0-16 A) has been experimentally investigated at both normal pressure (Hefei: altitude 50 m, 100 kPa) and reduced pressure (Lijiang: altitude 2400 m, 76 kPa; Lhasa: altitude 3650 m, 64 kPa). Polyethylene-insulated single-core wires, comprising Cu as the inner core of diameter 0.30, 0.50, and 0.80 mm and insulation thickness 0.15 and 0.30 mm, are used as samples. The experimental results clearly indicate that the height of the flame increases with the electric current and ambient pressure, but the flame width changes only slightly. At identical conditions, the finer the wire, the faster the flame spreads. The flame spread rate increases with the electric current and ambient pressure. A simplified thermal balance analysis concerning the load current is developed to calculate the flame spread rate, and the calculated flame spread rates are shown to be fairly consistent with the experimental values at different electric currents for different wires at both ambient pressures. In addition, the coupled effect of electric current and ambient pressure on the flame spread is discussed. These results may be meaningful for promoting the research process of wire fire safety.