How does a Ground Fault Circuit Interrupter (GFCI) operate?

A Ground Fault Circuit Interrupter (GFCI) operates primarily by detecting an imbalance between the Hot and Neutral wires. In a typical electrical circuit, the current flowing through the Hot wire should equal the current returning through the Neutral wire. If there is any difference in current, it suggests that some of the electrical current is escaping the circuit—often through an unintended path, which can be dangerous, such as through a person who has come into contact with water.

When the GFCI senses this imbalance, which may occur if an electrical current is leaking due to contact with a grounded surface, it swiftly interrupts the power supply to prevent electrical shock. This mechanism is crucial for safety, especially in areas where water is present, such as kitchens and bathrooms.

The other options do not accurately describe the primary function of a GFCI. While some GFCIs do require a manual reset after tripping after an imbalance is detected, their fundamental operation revolves around detecting that imbalance in the first place.