What is the function of a GFCI?

The function of a Ground Fault Circuit Interrupter (GFCI) is to enhance safety by quickly disconnecting power from a circuit when it detects a ground fault, reducing the risk of electric shock or electrical fires. Specifically, it monitors the amount of current flowing from the hot wire to the neutral wire. When it detects an imbalance, which indicates that current may be leaking to the ground, the GFCI reacts almost instantaneously, typically within milliseconds, to open the circuit and cut off the electricity.

This quick disconnection is crucial because ground faults can occur in environments where there is moisture or conductive materials present, increasing the risk of electrocution. Therefore, the GFCI is designed to enable a circuit to be opened before adequate ground-fault current can cause injury, making option B the correct answer.

The other provided options do not accurately describe the primary function of a GFCI. For instance, while it may seem related, preventing power surges relates more to surge protectors than to GFCIs. Additionally, measuring current flow is more associated with ammeters or circuit meters, and grounding all circuits does not align with the specific protective purpose of a GFCI, which focuses on detecting ground faults rather than grounding