Code Q&A

Q. What are the grounding requirements for a portable generator?

A. According to 250.34(A), the frame of a portable generator isn't required to be grounded (connected to the earth) if:

1. The generator only supplies equipment or receptacles mounted on the generator, and
2. The metal parts of the generator and the receptacle grounding terminal are connected to the generator frame.

According to 250.34(B), the frame of a vehicle-mounted generator isn't required to be grounded (connected to the earth) if:

1. The generator frame is bonded to the vehicle frame,
2. The generator only supplies equipment or receptacles mounted on the vehicle or generator, and
3. The metal parts of the generator and the receptacle grounding terminal are connected to the generator frame.

A portable or vehicle-mounted generator used as a separately derived system to supply equipment or receptacles mounted on the vehicle or generator must have the neutral conductor connected to the generator frame [250.34(C)]. Note: A portable or vehicle-mounted generator supplying fixed wiring for a premises must be grounded (connected to the earth) and bonded in accordance with 250.30 for separately derived systems and 250.35 for non-separately derived systems.