Grounding system for two separate voltage systems (480V and 208V 3P 4W)

[fandi]

Hello All,
A mixed use building uses 230.2(D) to have two systems (480V and 208V 3P 4W) in the same building. The 1,200A 480V switchboard is in a different room than the 3,000A 208V switchboard. Each has each own grounding system (EGC is #3/0 CU). My question is: Don't these two grounding systems have to connect to each other?
Thanks.

 

[texie]

Yes.

 

[ptonsparky]

They should both be tied to a common GES, whatever that may be.

 

[electrofelon]

I usually use the "GEC busbar" provision in 250.64(D) for multiple services

 

[fandi]

Thanks All.

 

[texie]

Thanks All.

We all jumped on and just yes but see 250.58 for verification.

 

[fandi]

We all jumped on and just yes but see 250.58 for verification.

It scares me when a senior PE engineer with more than 20 years of experience designs a big building for many people live there and forgot to tie the two ground systems together.

 

[winnie]

Presumably they were incidentally tied together by the utility neutral or by building steel. Not as it was supposed to be, but probably not all that bad.

-Jon