Effect of Ignition Method on Extinction Limit for a Flame Spreading over Wire Insulation

Flame spread tests were conducted to obtain Limiting Oxygen Concentrations (LOC) of electric wires in external flow condition of 100 mm/s. The ignition power and heating time were varied as parameters to reveal the effect of the ignition condition on the LOC value. In the experiments, polyethylene-coated Nickel-Chrome wires were used as the sample wires, and a coil heater was used as the ignition source, which consisted of 0.50 mm diameter Kanthal wire. Experiments were conducted in both normal gravity and microgravity. The experimental results show that the LOC gradually decreases as the ignition power or heating time increases and eventually it became almost constant.