Circuit Protection

4 of 27

FUSES
A fuse is the most common protection device. A fuse is placed in an electrical circuit, so that when current flow exceeds the rating of the fuse it "blows" or "blows out". The element in the fuse melts, opening the circuit and preventing other components of the circuit from being damaged by the overcurrent. The size of the metal fuse element determines its rating. Remember, excessive current causes excess heat, and it's the heat and not the current that causes the circuit protector to open. Once a fuse "blows" it must be replaced with a new one.