ECN Forum Forums Code Related Discussion NEC & other Code issues 175kw Generator grounding

I have a set of drawings from an engineer for a 175kw 120/240 single phase generator. In the drawing he has two ground rods at the generator and bonds the rods and the generator with 4/0 copper. He then shows the 4/0 copper running to the structure and bonding at the structure main/ATS (the main and ATS will be in one unit) with the grounding system. From the breaker in the generator he has two paralleled 1/0 running with the generator feeders as equipment grounds. My question is does the 4/0 from the rods and generator casing need to run to the structure grounding system? Isn’t the generator breaker the first disconnecting means and if the neutral and ground are bonded together in the generator doesn’t the paralleled 1/0’s satisfy the grounding of the structure not needing the 4/0 to be run all the way to the ATS? I’m not asking to doubt the engineer. It’s mostly for my own knowledge for future installations to make sure I’m not missing something I don’t understand.

Thanks
Mic

The grounding conductors are all going to be bonded together. The only question is how you deal with the grounded (neutral) conductor. That will depend on whether it is switched in the transfer equipment.
The ultimate goal is that you only have one main bonding jumper in the system in either condition (utility or generator)