What action do circuit-breaker types of GFCIs perform when a ground fault occurs?

When a ground fault occurs, circuit-breaker types of Ground Fault Circuit Interrupters (GFCIs) play a crucial safety role by opening the entire branch circuit. This means that the GFCI will disconnect the power to all outlets and devices connected to that particular circuit. The purpose of this action is to prevent electrical shock and reduce the risk of fires that can result from ground faults, which occur when electricity finds an unintended path to the ground, often through a person.

By opening the entire branch circuit, the circuit-breaker type of GFCI ensures that all potential sources of power within that circuit are cut off, providing a safer environment. This comprehensive approach is necessary because it is difficult to predict which specific appliance might be causing the fault; therefore, protecting the entire circuit is essential for safety.