Red Seal Construction Electrician Practice Exam

What device automatically disconnects circuits upon detecting a ground fault?

1. Fuse

2. Ground fault circuit interrupter (GFCI)

3. Transformer

4. Voltage regulator

The correct answer is: Ground fault circuit interrupter (GFCI)

A ground fault circuit interrupter (GFCI) is designed specifically to protect against electrical shock and fire hazards caused by ground faults. When the GFCI detects an imbalance in the electrical current flowing through the hot and neutral wires—indicating that some current is leaking to the ground—it automatically interrupts the circuit. This rapid disconnection occurs typically within milliseconds, significantly reducing the risk of serious injury or damage. In contrast, fuses are protective devices that disconnect a circuit when the current exceeds a certain level, but they do not specifically monitor for ground faults. Transformers manage voltage levels in electrical systems without the capability to detect ground faults. Voltage regulators maintain consistent voltage output but, like transformers, they do not function as safety devices for ground fault detection. Therefore, while all the other options serve important roles in electrical systems, the GFCI is uniquely effective at detecting ground faults and ensuring safety by automatically disconnecting the circuit.