ABSTRACT

Fuses are sized according to their rated current and voltage. If a fuse current is undersized then it is subject to nuisance tripping due to fl uctuations and spikes in the line voltage. If it’s oversized it can be a potential fi re hazard or a hazard to personnel. When replacing a fuse it is critical to use the same fuse type, since UL and CSA ratings are different from IEC ratings. For a 250 V fuse, for example, a 1.4-amp UL/CSA fuse is approximately the same as a 1-amp IEC rated fuse. Therefore, if a fuse manufactured to UL standards is replaced with a fuse manufactured to IEC standards, then the circuit will no longer be protected properly. And it goes without saying that it’s never a good idea, regardless of the circumstances, to bypass a fuse with a chewing gum wrapper or any other conductive material.