Back to Basics:  If you are new to electricity, please remember that fuses protect from over amperage, not over voltage.

 Amperage is the amount, or flow of electricity. Voltage is the force. A good analogy is water. Pressure is analogous to voltage. Volume is similar to amperage. For example a garden hose with a nozzle may be high pressure (voltage), but a low volume (amperage). A fire hydrant may be huge volume (amperage), but may only push water out a few feet due to its low pressure (voltage). When you multiply amps X volts you get watts.

 Every electrical circuit whether a motor or a computer, is designed to handle a specific amperage. The wires are only so big. If you try and run too many amps through the wires, they get hot and burn up. The purpose of a fuse or circuit breaker is to blow or trip before damage is done to the device or wiring.