What condition does a GFCI protect against?

• A. Current imbalance between hot and neutral
• B. Short circuit between hot and neutral
• C. Overload on the circuit
• D. Voltage surge

Answer: (A)

Ground fault protection is what a GFCI provides: it watches the current in the hot and neutral wires and trips if any current leaks out to ground. If a person or other path allows current to escape to ground, the currents in hot and neutral become imbalanced (even a small amount, typically a few milliamps), and the GFCI quickly shuts off power to prevent a shock. This device is specifically designed to detect ground faults, not to handle all electrical faults.

A short between hot and neutral wouldn’t create a leakage to ground, so there’s no imbalance for the GFCI to sense; such a fault is typically dealt with by overcurrent protection like a breaker or fuse. Overloads and voltage surges are also managed by different protections—overloads by overcurrent devices and surges by surge protectors—rather than primarily by a GFCI.