When a GFCI detects a ground fault, what action does it take?

• A. It interrupts power to the outlet or circuit to prevent electric shock.
• B. It reduces voltage to the entire building.
• C. It triggers a lighting cue.
• D. It sounds an alarm only.

Answer: (C)

When a GFCI detects a ground fault, it interrupts power to the outlet or circuit to protect against electric shock. It constantly compares the current in the hot and neutral conductors; if some current leaks to ground (a fault path), the difference is detected almost instantly, and the device trips—cutting off power to that specific receptacle or circuit. This safety action happens locally to prevent shock, not by reducing voltage to the whole building, triggering a lighting cue, or merely sounding an alarm. After the fault is resolved, the GFCI can be reset to restore power.