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

fandi

Senior Member
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.
 

fandi

Senior Member
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

Senior Member
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
 
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