Which device trips when it detects a current imbalance between hot and neutral?

• A. Ground fault circuit interrupter
• B. Circuit breaker
• C. Fuse
• D. Surge protector

Answer: (A)

When current leaves the hot conductor but doesn’t return on the neutral, it’s leaking to ground. A ground fault circuit interrupter is built to constantly monitor the current in both the hot and neutral conductors and detect any imbalance. If the difference exceeds a tiny threshold (a few milliamps), it trips within milliseconds to cut power and reduce the risk of electric shock. This is exactly what makes it the protective device for leakage faults, especially in wet areas where ground faults are more likely.

Other devices protect against different problems: a circuit breaker or fuse responds to overcurrent from overloads or short circuits, not leakage to ground; a surge protector guards against voltage spikes, not current imbalances. So the device that trips due to a current imbalance between hot and neutral is the ground fault circuit interrupter.