What is a fuse?
Fuses are really nothing more than short pieces of wire designed to melt if the current passing through them exceeds a certain limit. The idea is that if too much current passes through a circuit, the fuse melts, opening the circuit and stopping the flow of electricity. This prevents too much overheating, which could lead to fire. Fuses are designed to be easily visible and generally easily replaced. If one blows, it ought to be fairly easy to take out. Fuses are used primarily in older homes and cars. Homes built before 1965 used fuses, but since then circuit breakers have been in use.
What is a circuit breaker?
Circuit breakers are the more modern equivalent of fuses. Newer homes use these instead. Circuit breakers are essentially glorified switches that open in response to excess current. Residential circuit breakers, rather like fuses, work because of the overheating that comes with too much current. They contain bimetallic strips, which bend when heated. When the strip bends sufficiently, it opens the switch, opening the circuit and stopping the flow of current. The advantage with circuit breakers is that they need not be replaced every time a state of excess current is experienced. Unlike fuses, which are unusable after they blow, a circuit breaker can be closed by the flip of an external switch. This uses a compressed spring to reset the bimetallic strip. Fuseboxes contain multiple circuit breakers, each of which controls one part of your house's wiring.
What does it mean if my fuse or circuit breaker blows?
If a fuse or circuit breaker blows, it means that there was too much current in some part of a circuit. This could be a short circuit somewhere, or simply too many appliances plugged into one outlet. The second scenario would result in too much current being drawn to that particular outlet.
Notes about working with fuses and circuit breakers
Work with fuses and circuit breakers is not the sort of thing you want to do on your own. Making a mistake can lead to electric shocks and fires. That said, here are some tips about fuses and circuit breakers.
- Don't put in a fuse or circuit breaker that accommodates more current than it should, just because you don't want it to blow. The point of the fuse/circuit breaker is that it does blow when there's too much current.
- If an extension cord feels warm, disconnect appliances. This means that current is probably approaching dangerous levels.
- Wait some minutes before flipping the switch on a circuit breaker. The bimetallic strip inside needs some time to cool down. Only then can it be reset.
- If a fuse/circuit breaker blows, don't just replace it/flip it back. Unless you're sure it was because of too many appliances being used at once, try to figure out what caused to problem to ensure that there's nothing too serious behind the blow.