True or False: The circuit-breaker types of GFCI only open part of the circuit if a ground fault occurs.

The statement is false because circuit-breaker types of Ground Fault Circuit Interrupters (GFCIs) are designed to open the entire circuit when a ground fault occurs rather than just part of it. This safety feature is crucial because it ensures that the entire circuit is de-energized, preventing electrical shock hazards. By tripping the whole circuit, the GFCI reduces the risk of continuous electrical flow that could pose a danger to anyone in contact with devices or wiring connected to that circuit.

Other options might suggest partial opening under certain conditions, but GFCIs are specifically engineered to protect people by interrupting the entire circuit whenever a ground fault is detected. Therefore, the correct understanding of GFCI operation is essential for safety in electrical systems.