What is the difference between a fuse and a circuit breaker in terms of resetting after an event?

• A. A fuse is single-use and must be replaced; a circuit breaker can be reset
• B. A fuse can be reset after a fault; a circuit breaker must be replaced
• C. Both are single-use
• D. Both can be reset

Answer: (A)

The main distinction is whether the protective device can be reused after an event. A fuse protects by having a thin conducting element that melts when current is too high; once it melts, the circuit is opened and the fuse must be replaced with a new one of the same rating. A circuit breaker uses a switch that trips open when an overcurrent or fault occurs, and after the fault is cleared you can reset the breaker by turning it back on (or pressing a reset button). So fuses are single-use and must be replaced, while circuit breakers are designed to be reset and reused. Remember to check the cause of the fault and replace with the correct rating when resetting or replacing.