In a subpanel, the neutral bus is isolated from the grounded bus.

• A. Bonded to the grounded bus
• B. Isolated from the grounded bus
• C. Connected to the hot bus
• D. Floating with no relation

Answer: (B)

In a subpanel, keeping the neutral and grounding systems separate is essential. The neutral conductor carries the normal return current back to the service, while the equipment grounding conductor is intended to carry fault current only and should carry no current during normal operation. By isolating the neutral bus from the grounded bus, you prevent normal neutral current from flowing on the grounding path, which keeps metal enclosures safe and ensures a clear, dedicated fault-path back to the source. The grounding bus is bonded to the panel enclosure and to the grounding electrode system, but there is no bond between neutral and ground at the subpanel. Bonding neutral to ground at the subpanel would create parallel current paths for return currents and could energize exposed metal parts, defeating the safety purpose of the grounding system.