Electrical causes of fire

When a fire is ignited by electrical causes, it is important to take into account how much electrical energy is required to cause a fire to occur by fulfilling the third and forth component of the combustion tetrahedron as mentioned in the previous section, the production of enough heat for the material to reach its ignition temperature and thus is sufficiently supplied with the heat to maintain the uninhibited self-sustaining reaction of combustion, assuming that the other 2 conditions of fuel and oxidizer are already available. Conduction is the predominant method of heat transfer and buildup when electrical causes are concerned and should be bared in mind.

Conduction heating

Under normal circumstances, a negligible heat amount of heat is produced when a current flows through a conductor due to the resistance of the conductor, such as a wire. An overload might occur when unsuitable or incompatible devices are used. For example, when an extension cord, such as one with a capacity of 5 amperes, is extended to an appliance circuit that runs at a higher current, such as 20 amperes, in an event of a short circuit, the current flowing through the extension cord will be 20 amperes. This is 4 times the current the extension wire was designed to contain. This will result in the wire operating at a much higher temperature which would then accumulate heat and might eventually start a fire.