666. What is a short in the electrical system of a car? What causes shorts? — BM, Puyallup, WA
A short circuit is a conducting path that allows electric current to flow from its source (typically the positive terminal of a battery) to its destination (typically the negative terminal of that battery) without passing through the equipment that the current is supposed to operate. The conducting path is thus a short cut for the current that allows it to complete its circuit too quickly, hence the name "short circuit." In virtually all automobiles, the whole body of the car is connected to the negative terminal of the battery so that any accidental conducting path from the battery's positive terminal to the body of the car is a short circuit. Since a short circuit doesn't include a device that's designed to consume electric power, the wires of the short circuit must consume that electric power. They often become hot and may cause a fire.