Ham Radio General Class Practice Test

Which of the following conditions will cause a Ground Fault Circuit Interrupter (GFCI) to disconnect the 120 or 240 Volt AC line power to a device?

1. Current flowing from one or more of the hot wires to the neutral wire

2. Current flowing from one or more of the hot wires directly to ground

3. Over-voltage on the hot wire

4. All of these choices are correct

The correct answer is: Current flowing from one or more of the hot wires directly to ground

A Ground Fault Circuit Interrupter (GFCI) is specifically designed to protect against electric shock by quickly disconnecting the power when it detects an imbalance in electrical current between the hot and neutral wires. This typically happens when current flows directly to earth ground, which is considered a ground fault. When current flows from one of the hot wires directly to the ground, it creates a situation where not all of the current returning through the neutral wire is accounted for. The GFCI senses this difference (the imbalance) and interrupts the circuit, effectively reducing the risk of shock or electrocution. In contrast, current flowing from the hot wire to the neutral wire does not indicate a ground fault, as it involves the normal operation of the electrical circuit. Over-voltage conditions can damage devices but do not trigger the GFCI. Therefore, the condition that most directly causes a GFCI to disconnect power to a device is when current flows directly to ground, making that the correct understanding.