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Car Fuses and Wiring
Home Electricity
Cigarette Lighters

How does a fuse work?

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May 13, 2012 5:20PM

A fuse is a safety device to prevent excess current flowing in an electric circuit. It consists of a thin metal wire of low resistance and low melting point. When an electrical appliance or some other piece of electrical equipment becomes faulty, therefore allowing an excess electric current to flow through its circuit, this causes the wire inside the fuse to melt and thus break the flow of current.

Fuses, by design are a one-time-use protective device - once they are used ("burn out"), they're worthless. That is why homes typically use circuit breakers: a breaker acts similarly to a fuse in that it opens a circuit when excessive current flows, but - because nothing actually melts inside it - it can then be reset without having to be replaced by a new one, as has to be done for a fuse.

If there were no fuse in the circuit, serious damage could be caused to the wiring which feeds the equipment. It could get so hot that it catches on fire, which might start a fire in the building or vehicle in which the electrical equipment is installed.

For more information see the answer to the Related Question shown below.