Most people who are not familar with electricity don't know that electrical fuses protect from over amperage, not over voltage.
Amps or amperage is the flow, or amount of electricity. Voltage has to do with the force the electricity current flows. A example of this would be a fire hose with a nozzle delivers high pressure (voltage), but low volume (amperage). The fire hydrant may have huge volume (amperage), but will only push the water a few feet due to it's low pressure (voltage). So when you multiply amps x volts you get the wattage.
Every electrical circuit whether a large shop machine or motor, is setup to handle specific amperage. Your wiring is only so big, and if you try running too many amps through the wires, they'll get hot and melt. The purpose of a electrical fuse or circuit breaker is to trip or blow before damage is done to the machine, electrical product, or wiring.
Standard Home Fuses
New homes have circuit breakers but many older homes have a fuse box that which fuses screw into sockets similar to light bulb sockets. There are two types of bases for sockets, the Edison Base which are Type T Fuses and the Rejection Base which are Type S Fuses. The Edison Type T base fuse screws directly into the socket in the fuse box. The Rejection Base Type S fuse actually screws into a adapter base, which locks the fuse into the fuse box. Each of the Type S fuses has a different size adapter base for each different amperage rating fuse. With the different types of fuse bases you are unable to put a larger amp rated fuse into a smaller amp circuit.
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