A ground-fault circuit-interrupter receptacle is a Class A device intended to interrupt the circuit when the current to ground is how many milliamperes or higher?

• A. 2 mA
• B. 6 mA
• C. 30 mA
• D. 60 mA

Answer: (C)

The main idea is how a ground-fault protective device decides when to cut power. A ground-fault circuit-interrupter monitors the current in the hot and neutral conductors and trips when there’s an imbalance, meaning some current is leaking to ground. For a Class A device, the intended trip threshold is 30 milliamperes or higher. This level provides personal protection by interrupting at a leakage that could be dangerous, while avoiding nuisance trips from small, normal leakage. If the threshold were much lower, like a couple of milliamperes, it would trip too often; if it were much higher, a real ground fault could go unnoticed longer.