Exterior Switchboard Grounding

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Wrd4spd

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Los Angeles
I have a new 4000A-277/480V switchboard being installed outside of an existing building. The switchboard will re-feed the existing buildings main power panel, but it also feeds panels at two other remote structures and several large pieces of remote equipment. Since the switchboard is not dedicated to or located within the existing building, would the only service grounding requirements for this 4000A switchboard be two ground rods per NEC 250.50 connected with #6 CU per NEC 250.66(A)? Each of the buildings/ structures would be considered remote and need to be provided with individual grounding electrode systems per NEC 50.32.

I'm just looking or me feedback. Did I overlook something here?

Thanks!
 
Wrd4spd said:
Since the switchboard is not dedicated to or located within the existing building, would the only service grounding requirements for this 4000A switchboard be two ground rods per NEC 250.50 connected with #6 CU per NEC 250.66(A)?
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Sounds good to me. Some people dont like the idea of such a "small ground" on such a big service, but it is very unlikely you will get any gain from something more extravagant. Keep in mind you may need to go up to #4 for the GEC depending on how it is routed, 250.64(B).
 
When similar situations have occurred locally the manner in which it has been addressed has seemed to depend on distances.
Normally if "outside the building" ends up being just a few feet away the inspectors have looked at it as part of the building and required connection to the building GES, etc. Such details as it being in a separate structure or free standig gear have all influenced the decision.
 
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