Circuits HA-1, -4, and -11 with a neutral have been pulled in EMT from a 277/480-volt, 3Ø, 4W panelboard to some high-bay luminaires. If the wire from breaker 11 comes in contact with the EMT, ___ will occur.

Circuits HA-1, -4, and -11 with a neutral have been pulled in EMT from a 277/480-volt, 3Ø, 4W panelboard to some high-bay luminaires. If the wire from breaker 11 comes in contact with the EMT, ___ will occur.

• A. a short circuit
• B. a backfeed
• C. a ground fault
• D. an arc-fault

Answer: (C)

When a live conductor touches a grounded metal raceway (EMT), a direct path to ground is created. The EMT is bonded to the equipment grounding system, so current can flow from the hot wire to earth through that metal path. This is a ground fault—the fault current returns via the grounding path rather than through the intended neutral, and it will trip protective devices to clear the fault. A short circuit would involve a path between conductors (hot to hot or hot to neutral), not specifically hot to a grounded metal enclosure. An arc-fault is about arcing across an insulating gap, and backfeed is power fed back into a circuit; neither describes the hot-to-ground fault described here.

When a live conductor touches a grounded metal raceway (EMT), a direct path to ground is created. The EMT is bonded to the equipment grounding system, so current can flow from the hot wire to earth through that metal path. This is a ground fault—the fault current returns via the grounding path rather than through the intended neutral, and it will trip protective devices to clear the fault. A short circuit would involve a path between conductors (hot to hot or hot to neutral), not specifically hot to a grounded metal enclosure. An arc-fault is about arcing across an insulating gap, and backfeed is power fed back into a circuit; neither describes the hot-to-ground fault described here.