Transformer and Panel Grounding

[cripple]

I have a 3-phase pad mounted transformer primary rated 13.2KV and 480Y/277 on the secondary. The transformer is grounded to a 4/0 copper conductor that is installed in the pad. The transformer and the panel serviced are both on the same pad and located about 4 feet apart, the print shows to install the three phase conductors and a grounded conductor, which is be grounded at the panel to the same 4/0 copper conductor the transformer is grounded.

QUESTION: Would this installation violate 250.6, since by grounding both the transformer and the panel to the same grounding electrode, we will be creating a parallel path with the grounded conductor.

 

[charlie]

Re: Transformer and Panel Grounding

Is this an electric utility owned transformer or a separately derived system? After that is established, we can work on the rules.

 

[cripple]

Re: Transformer and Panel Grounding

The transformer is customer owned. The 13.2 KV distribution system is also customer owned, but to apply the NEC rules the customer as make a determination that this type of installation the transformer would be considered as utility owned.