Effect of insulation thickness on downward flame spread over electric wire

Abstract

Effect of insulation thickness on the flame spread over electric wire is investigated analytically. Previous study has experimentally observed that flame spread rate shows a non-monotonic trend with respect to the insulation thickness. The flame spread model developed in this study successfully reproduces the non-monotonic behavior of the flame spread rate with respect to insulation thickness. It was revealed that the effect of solid geometry on the flammability of composite materials cannot be explained by the conventional thermally thin or thermally thick theories, and the cause of the unique behavior of spread rate versus insulation thickness is discussed based on the analytical results.