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What is the intent of 250.34(B)(2) in the NEC?

Question asked by jcsmith on Dec 10, 2018
Latest reply on Dec 12, 2018 by jcsmith

NEC 250.34(B) allows omission of a grounding electrode connection for a vehicle-mounted generator when certain conditions are met; in short, when:

  1. The generator and vehicle frames are bonded together,
  2. Equipment powered by the generator is either mounted on the generator or supplied by receptacles mounted on the generator,
  3. Proper bonding is done throughout.

My concern is with the second part of #2, which implies that if a piece of equipment is hard-wired to the generator instead of cord-connected there is a deficiency and that connecting the vehicle frame to a grounding electrode somehow corrects the deficiency. I do not understand the reason for this; assuming all other code requirements are met, just what is it about hard-wiring vs. cord-connection that necessitates this restriction?