When it comes to fire, most people expect a flammable material such as wood to catch fire, and they assume water can be used to extinguish that fire. An electrical fire, which is normally caused by overloading or from excess heat generated by an electrical device or appliance, follows different rules. Electrical fires occur for three main reasons: electrical arc, heating without an arc, and external heating. Throwing water on an electrical fire only makes it bigger and can cause electrocution to the person with the water; this is why dry chemicals are used to fight it.
An electrical fire can be caused in three different ways, and the first is arcing. In this case, which happens mostly with heaters and other appliances that create heat, the heat generated by the unit is too much for the wires to handle. In response to the heat, the sheath around the wires melts, and the internal metal is exposed. The metal soon degrades, causing an electrical arc. When this arc occurs, the fire starts.
The second way is poor wiring, which results in extreme heat, but no arc. In this scenario, the wiring is not configured correctly, so wires that should not be near each other, or wires that are not suited for the purpose of the device, are being used. The parts or positioning is not correct, so it is
Fire is separated by class, based on what started the fire. Electrical fires are known as class C, or class E in Australia, and are put out with dry chemicals. The most common chemical in these extinguishers is carbon dioxide. If a class C extinguisher is not available, baking soda also can be used.
The third cause of an electrical fire is external heating. This version is much like the first cause, and the heating may be enough to melt the wires and cause an arc or overload. The difference is that the heat occurs from outside the device. An electrical fire caused by external heat is rare, unless a powerful heater is trained on the device or the device is within a fire already.
When an electrical fire starts, the best thing to do first is turn off the power. This minimizes the chance of the fire spreading and, for minor fires, may take care of the problem. This is not guaranteed, though, so it is best to use an appropriate extinguisher, just in case.