Which of the following is an example of an electrical protective device?

• A. Smoke detector
• B. Heat detector
• C. Ground-fault circuit interrupter (GFCI)
• D. Photoelectric detector

Answer: (C)

An electrical protective device is meant to interrupt power when something hazardous is detected, to prevent harm. A ground-fault circuit interrupter does that by monitoring the current in the hot and neutral conductors and tripping within milliseconds if there’s an imbalance, which indicates current leaking to ground through a person or wet surface. This quick shutdown is what protects people from electric shock.

The other items serve as sensing devices for fire. Smoke detectors and photoelectric detectors alert you to smoke, while a heat detector alerts you to high temperatures. They warn of fire but do not automatically cut power, so they’re not electrical protective devices.