Which device, after it clears an overload, is not able to be reset?

Which device, after it clears an overload, is not able to be reset?

• A. Recloser
• B. MCCB
• C. Circuit breaker
• D. Fuse

Answer: (D)

Fuses are non-resettable protective devices. When current exceeds the fuse’s rating, the thin metal element heats up and melts, opening the circuit. Once the fuse has blown, it cannot be reset; you must replace it with a new one of the same rating to restore protection and service. In contrast, other protective devices are designed to trip and then be reset or automatically reclose after the fault is cleared. A recloser will interrupt current and then attempt to reclose after a short time; a molded case circuit breaker or standard circuit breaker will trip and can be reset (manually or automatically) once the fault is fixed. That makes the fuse the only option that cannot be reset after it clears an overload.

Fuses are non-resettable protective devices. When current exceeds the fuse’s rating, the thin metal element heats up and melts, opening the circuit. Once the fuse has blown, it cannot be reset; you must replace it with a new one of the same rating to restore protection and service.

In contrast, other protective devices are designed to trip and then be reset or automatically reclose after the fault is cleared. A recloser will interrupt current and then attempt to reclose after a short time; a molded case circuit breaker or standard circuit breaker will trip and can be reset (manually or automatically) once the fault is fixed. That makes the fuse the only option that cannot be reset after it clears an overload.