How does a GFCI function to protect from electrical shock?

A Ground Fault Circuit Interrupter (GFCI) functions by measuring current flow discrepancies between the energized (hot) conductor and the neutral conductor. Under normal circumstances, the current flowing through these two conductors should be equal. If there is a difference in these current levels, it typically indicates that some electricity is flowing through an unintended path, such as through a person who may be in contact with the circuit.

The GFCI continuously monitors the current flow and, if it detects an imbalance of as little as 4 to 6 milliamperes, it interrupts the circuit within milliseconds, significantly reducing the risk of electrical shock. This rapid disconnection is crucial for preventing serious injuries or fatal shocks, especially in wet locations where the risk is higher.

This protective feature is vital in areas like bathrooms and kitchens where water is present, as it provides a layer of safety by proactively responding to potential hazards.