What is the primary reason for using a ground fault circuit interrupter (GFCI)?

The primary reason for using a ground fault circuit interrupter (GFCI) is to protect against electric shock. GFCIs are designed to continuously monitor the current flowing through a circuit. If they detect an imbalance between the outgoing and incoming current, which could occur if current is leaking to the ground (such as through a person), the GFCI quickly shuts off the electrical supply within milliseconds. This rapid response is crucial in preventing potentially fatal electric shocks.

The devices are particularly important in environments where water and electricity are in close proximity, such as bathrooms, kitchens, and outdoor areas, where the risk of electric shock is heightened. While GFCIs also contribute to reducing the risk of electrical fires and may have broader safety implications, their primary function is to ensure human safety by preventing shocks.