What is a circuit breaker and how does it differ from a fuse?

• A. A fuse can automatically reset after a fault
• B. A circuit breaker can automatically disconnect on fault and can be reset; a fuse is a one-time device that must be replaced after a fault
• C. A fuse provides overcurrent protection and can be reset
• D. A circuit breaker is slower to react than a fuse

Answer: (B)

Overcurrent protection devices interrupt faulty current, but they differ in how you recover after a fault. A circuit breaker automatically opens the circuit when it detects a fault and can be reset after tripping, making it reusable—you simply reset or flip the switch back on. A fuse uses a metal link that melts when current is excessive, opening the circuit once, and then it must be replaced after a fault. So the circuit breaker provides reusable protection with automatic disconnection, while a fuse provides a one-time protection that requires replacement.