250.34 Portable and Vehicle-Mounted Generators.
(A) Portable Generators. The frame of a portable generator
shall not be required to be connected to a grounding
electrode as defined in 250.52 for a system supplied by the
generator under the following conditions:
(1) The generator supplies only equipment mounted on the
generator, cord-and-plug-connected equipment through
receptacles mounted on the generator, or both
(B) Vehicle-Mounted Generators. The frame of a vehicle
shall not be required to be connected to a grounding
electrode as defined in 250.52 for a system supplied by a
generator located on this vehicle under the following
conditions:
(2) The generator supplies only equipment located on the
vehicle or cord-and-plug-connected equipment through
receptacles mounted on the vehicle, or both equipment
located on the vehicle and cord-and-plug-connected
equipment through receptacles mounted on the vehicle
or on the generator,