What is the main difference between a fuse and a circuit breaker?

What is the main difference between a fuse and a circuit breaker?

• A. A fuse is non-resettable and must be replaced after it blows.
• B. A circuit breaker is non-resettable after tripping.
• C. A fuse can be reset after it blows.
• D. A circuit breaker automatically re-energizes the circuit after tripping.

Answer: (A)

The main distinction is how each protective device behaves after an overcurrent event. A fuse uses a thin metal element that melts when too much current flows, permanently breaking the circuit. Once a fuse has blown, it cannot be reused and must be replaced with a new one. A circuit breaker, by contrast, is a resettable switch that trips open to interrupt the current and can be reset to restore power after the fault is cleared. This is why the statement about a fuse being non-resettable and needing replacement after it blows is the best description. The other options misstate typical behavior: breakers are not non-resettable, fuses cannot be reset, and breakers do not automatically re-energize the circuit after tripping without a manual (or automatic) reset step.

The main distinction is how each protective device behaves after an overcurrent event. A fuse uses a thin metal element that melts when too much current flows, permanently breaking the circuit. Once a fuse has blown, it cannot be reused and must be replaced with a new one. A circuit breaker, by contrast, is a resettable switch that trips open to interrupt the current and can be reset to restore power after the fault is cleared. This is why the statement about a fuse being non-resettable and needing replacement after it blows is the best description. The other options misstate typical behavior: breakers are not non-resettable, fuses cannot be reset, and breakers do not automatically re-energize the circuit after tripping without a manual (or automatic) reset step.