Which device is designed to automatically disconnect power when a ground fault is detected?

Which device is designed to automatically disconnect power when a ground fault is detected?

• A. A fuse
• B. A traditional circuit breaker
• C. A surge protector
• D. A GFCI

Answer: (D)

A ground fault circuit interrupter (GFCI) is designed to automatically disconnect power when a ground fault is detected. It constantly monitors the current flowing through the hot and returning through the neutral conductors. If some current leaks to ground—such as through a person or moisture—the hot and neutral currents become unbalanced. When the difference exceeds a small threshold (about 4–6 milliamps), the GFCI trips and opens the circuit within milliseconds, stopping the current to prevent electric shock. This safety action is different from how other devices operate. A fuse works by blowing open when current gets high, but it doesn’t sense leakage to ground. A traditional circuit breaker trips on overloads or short circuits, not necessarily a ground fault. A surge protector mainly guards against voltage spikes and isn’t designed to disconnect on ground faults. GFCIs are commonly used in wet or damp locations—bathrooms, kitchens, outdoors—and can be installed as outlets or as breakers in the panel.

A ground fault circuit interrupter (GFCI) is designed to automatically disconnect power when a ground fault is detected. It constantly monitors the current flowing through the hot and returning through the neutral conductors. If some current leaks to ground—such as through a person or moisture—the hot and neutral currents become unbalanced. When the difference exceeds a small threshold (about 4–6 milliamps), the GFCI trips and opens the circuit within milliseconds, stopping the current to prevent electric shock.

This safety action is different from how other devices operate. A fuse works by blowing open when current gets high, but it doesn’t sense leakage to ground. A traditional circuit breaker trips on overloads or short circuits, not necessarily a ground fault. A surge protector mainly guards against voltage spikes and isn’t designed to disconnect on ground faults. GFCIs are commonly used in wet or damp locations—bathrooms, kitchens, outdoors—and can be installed as outlets or as breakers in the panel.