Multiple service equipment panels in one building

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zia

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We have 4 service equipment panels in one building supplied from transformers located in 2 separate outside buildings. The structural building has a ground grid.Is it OK to connect each service equip panel to the ground grid and bond with the grounded neutral and equipment ground in each case.I guess we should maintain segregation such that feeders and branch circuits from one service equip panel are grounded only in that panel and there is no intermixing
 
Re: Multiple service equipment panels in one building

Zia...I'll take a stab at this...

You must have a connection of the grounded conductor to a grounding electrode at those separate buildings and a system bonding jumper connected from the grounded conductor to the frame of the separately derived system.

So...you have the choice in each case to either bring the grounding conductor to the main building with the feeder or not. If you do bring the grounding conductor to the main building, then you must float the grounded conductor.

In either case you must ground to the grounding grid (or electrode as it may be called) that you have mentioned from all panels installed. Bond metal water pipe systems/structural steel, also.

Also be carefull not to creat any parallel paths for neutral current to the source.

shortcircuit2
 
Re: Multiple service equipment panels in one building

250.52(B) doesn't prohibit it.

Consider the fact that all grounded services are grounded to the same earth.

I guess we should maintain segregation such that feeders and branch circuits from one service equip panel are grounded only in that panel and there is no intermixing
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Yeah. 250.28
 
Re: Multiple service equipment panels in one building

zia...physis...I don't get the segregation part of the post?

Are we saying that equipment grounding conductors (EGC) of one service should not intermix with EGC of another service in this building?

shortcircuit2
 
Re: Multiple service equipment panels in one building

As I see it the transformers share a common grounded neutral from the primary, and the services in the building probably share common electrodes such as building steel, metal water pipes, as well as non-electrode connecting grounding paths such as vents, gas pipes, etc.

So you will have neutral current circulating in various parallel paths between services and between Tfrmers. I wish I knew a way to segregate the services but I don't see a way.

Karl
 
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