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

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

• A. A fuse interrupts current by melting its element; a breaker interrupts current by switching and can be reset after tripping.
• B. A fuse is resettable; a breaker is single-use.
• C. A fuse provides overvoltage protection.
• D. A fuse is designed for DC circuits only.

Answer: (A)

The difference lies in how each device stops current and what happens after a fault. A fuse interrupts current by melting its metal element when excessive current flows. Once it melts, the circuit is open and the fuse is spent, requiring replacement. A circuit breaker uses an internal switch that trips open when the current is too high; after the fault is cleared, it can be reset by flipping the switch (or pressing a reset button), restoring power without replacing the device. So, fuses are single-use and must be replaced after they interrupt, while circuit breakers are reusable and can be reset. This is why statements claiming fuses are resettable or that breakers are single-use aren’t accurate. Fuses protect primarily against overcurrent (not overvoltage) and can be used with both AC and DC circuits; circuit breakers serve the same protection purpose but with resettable operation.

The difference lies in how each device stops current and what happens after a fault. A fuse interrupts current by melting its metal element when excessive current flows. Once it melts, the circuit is open and the fuse is spent, requiring replacement. A circuit breaker uses an internal switch that trips open when the current is too high; after the fault is cleared, it can be reset by flipping the switch (or pressing a reset button), restoring power without replacing the device.

So, fuses are single-use and must be replaced after they interrupt, while circuit breakers are reusable and can be reset. This is why statements claiming fuses are resettable or that breakers are single-use aren’t accurate. Fuses protect primarily against overcurrent (not overvoltage) and can be used with both AC and DC circuits; circuit breakers serve the same protection purpose but with resettable operation.