An electrician is installing a sub-panel in a detached garage, fed by a 60 A, 120/240 V feeder from the main service panel in the house. How should the grounded (neutral) conductor and the equipment grounding conductor be handled in the sub-panel?

Question: An electrician is installing a sub-panel in a detached garage, fed by a 60 A, 120/240 V feeder from the main service panel in the house. How should the grounded (neutral) conductor and the equipment grounding conductor be handled in the sub-panel?

Answer options:

• The neutral bus and the equipment grounding bus must be bonded together. ✅ The neutral bus must be isolated from the equipment grounding bus, and the equipment grounding conductor must terminate on its own bus.
• Both the neutral and ground conductors should be terminated on the neutral bus, which is isolated from the panel enclosure.
• Only the phase conductors and the neutral conductor are required; a separate grounding conductor is not needed for a sub-panel.

Correct answer: The neutral bus must be isolated from the equipment grounding bus, and the equipment grounding conductor must terminate on its own bus.

Explanation: In a sub-panel in a detached building, the neutral bus must be isolated from the panel enclosure and the equipment grounding bus. The equipment grounding conductor from the main panel should terminate on a separate grounding bus, which is bonded to the sub-panel enclosure. This prevents parallel neutral current paths on the grounding conductors and keeps the entire grounding system at the same potential.