Downward flame spread and extinction phenomena of externally heated electric wire:

Effect of materials geometry and opacity on its flammability

Abstract

An experimental study was conducted to investigate the influences of external radiative heating and materials geometry and opacity on the flammability limits of electric wires. Firstly, overall characteristics of flame behavior over each sample wire were investigated based on the direct observation. It was found that downward spreading flame shows distinct types of unstable flame spread depending on the shape of wire at near extinction conditions and results in different extinction mechanisms. Among the results it was also found that external radiative heating extends the flammability limits of wire samples. Comparison were also made to examine the effect of metal core and materials opacity on the flammability of electric wires.