Effect of thermal behaviour on burning of plactic coating for electric cables

Abstract

Cable is in the first place amongst the cause of fire. Fires are always triggered by unsafe and non-standard conditions, so, we can approach safety if we know the properties of cables we want to use. Cable fires may have two starting points: one is the heat reaching the plastic insulation of cables, due to the fire created by burning, the other one may be due to the fire generated by the overvoltage in the inappropriately sized cables when the outer plastic coating begins to burn. The basic condition of fire retardant is that wire breaks or short circuits may not occur in a cable system. During this research, both effects are tested on fire retardant cables. On the one hand, we exposed wires of various plastic sheaths to flame and to heat, as well as tested at which actual oxygen content they start combustion and flame propagation. Each combustion starts with thermal decomposition, so it is of particular importance in the thermal behavior of plastic coatings and the expected burns. The selected samples were examined by thermoanalytical method (DTA, TG, TDG). The most important parameters are the weight loss and the initial temperature of the decomposition, which also indicate the expected ignition point of the plastics.