Experimental Study on the Fire Smoke Characteristics of an Insulated Wire Jacket for Indoor Wiring Using a Smoke Density Chamber

Abstract

A wire jacket that prevents leakage of electric current flowing through wires is made of polymer composites. The flame spreads widely with a large amount of smoke passing through the wire jacket when a fire occurs. As smoke hinders safe evacuation, it is important to determine the smoke characteristics of the wire jacket for safe evacuation. Therefore, in this study, the specific optical density was measured for 1800 s in the presence and absence of ignition flame under a radiant heat flux of 25 kW/m2 according to the ISO 5659-2 combustion chamber method. From the experimental results, the extinction coefficient and visibility indicating the degree of transmission of light and VOF4 indicating the smoke density characteristics at the beginning of combustion were derived. The experiment was conducted with a wire jacket comprising PVC and a wire jacket comprising XLPE of low-toxicity flame-retardant cross-linked polyolefin. The maximum specific optical density was higher for PVC than for XLPE with and without the ignition flame. Except for the case of XLPE with an ignition flame, the extinction coefficient of the wire jacket was > 3.5 m-1, with a visibility of 0.2-2 m. PVC exhibited a higher maximum specific optical density in the absence of the ignition flame than in the presence of the ignition flame; however, VOF4 was higher in the presence of the ignition flame.