What is the primary purpose of a ground fault circuit interrupter (GFCI)?

The primary purpose of a ground fault circuit interrupter (GFCI) is to prevent electric shock. A GFCI is designed to detect imbalances in electrical current between the hot and neutral wires. When it senses that the current is flowing through an unintended path—such as through a person who may be in contact with the ground—it interrupts the electrical circuit almost instantaneously. This rapid disconnection significantly reduces the risk of serious injury or fatality due to electric shock, especially in wet or damp environments where the likelihood of ground faults is increased.

While measuring ground resistance, maintaining constant voltage, and measuring current overload are important aspects of electrical systems, they do not pertain to the core function of a GFCI. The focus of the GFCI is solely on safety by cutting off the circuit to prevent harm from electric shocks. This makes it an essential safety device in areas like kitchens, bathrooms, and outdoor outlets where the risk of water contact is higher.