What is a ground fault circuit interrupter (GFCI)?

A ground fault circuit interrupter (GFCI) is designed to protect people from electric shock by monitoring the flow of electrical current in a circuit. It continuously checks for an imbalance between the current flowing into an electrical device and the current returning. This imbalance, often caused by a ground fault, indicates that some of the current is escaping the intended path, potentially through a person who may be grounded.

When a GFCI detects this imbalance, it responds quickly by cutting off the electrical power to the circuit, thus reducing the risk of injury or fatality due to electric shock. This protective function is particularly crucial in wet areas, such as bathrooms and kitchens, where the risk of electric shock is higher.

The other options describe functions that do not align with the purpose of a GFCI. Amplifying signals, measuring voltage, or increasing current flow are different processes that do not involve the safety mechanisms that a GFCI provides.