A device that will de-energize a circuit if the current to ground exceeds a predetermined value is a?

A device that will de-energize a circuit if the current to ground exceeds a predetermined value is a?

• A. Ground fault circuit interrupter (GFCI)
• B. Circuit breaker
• C. Fuse
• D. Residual current device

Answer: (A)

A device that protects people from electric shock by shutting off power when leakage to ground is detected works by monitoring how much current is flowing in the live and return conductors. Under normal conditions those currents are equal. If some current leaks to ground—such as through a person touching a live surface and a grounded path—the currents no longer balance. The difference is detected and the device trips, disconnecting the circuit in a fraction of a second. This protection is typically configured to trip on very small leakage, often a few milliamps, which makes it especially important in wet or outdoor areas where ground faults are more likely. Standard circuit breakers and fuses protect against overcurrent, not small ground-leakage faults, so they won’t always respond to a shock hazard from a ground fault. In many regions, this protection is called a residual current device, but the essential idea is the same: trip on leakage current to ground to prevent shock.

A device that protects people from electric shock by shutting off power when leakage to ground is detected works by monitoring how much current is flowing in the live and return conductors. Under normal conditions those currents are equal. If some current leaks to ground—such as through a person touching a live surface and a grounded path—the currents no longer balance. The difference is detected and the device trips, disconnecting the circuit in a fraction of a second. This protection is typically configured to trip on very small leakage, often a few milliamps, which makes it especially important in wet or outdoor areas where ground faults are more likely. Standard circuit breakers and fuses protect against overcurrent, not small ground-leakage faults, so they won’t always respond to a shock hazard from a ground fault. In many regions, this protection is called a residual current device, but the essential idea is the same: trip on leakage current to ground to prevent shock.