EGC between buildings with seperate services

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Today we installed a switch between two buildings that are not fed from the same service. I am familiar with the issue of three wire feeders and metallic paths between two structures where one structure is fed from the other (250.32), but with seperate services:
1. Are there any code issues and/or safety issues?
2. What should I do with the switch EGC. if possible, should it remain isolated from the remote structure's ground system?
 
The general rule is that a structure can be fed with only one source. There are exceptions. See 225.30 or 230.2.

Do you comply with one of the exceptions?

Jim T
 
I may be stretching here, but 250.144 might shed some light on this...that is if you think the same grounding principles apply with a switch as they do with a permanent piece of equipment as specified in 250.134. IMO, you need to bond the EGC from each service and also the 2 grounding electrode systems. I could be wrong...

Edit to add, I am using 2005 NEC.
 
the circuit in question is a three way switch between the two structures - fed and loaded at the same structure - thus I dont see any issue with the one source requirement. The potential code/safety issue I see is with neutral current flowing on the switch circuit egc between the two services?
 
...one more piece of info: If in the remote structure (dead end 3-way) the switch were in its own box, then I would not see an issue because the switch circuit egc would be isolated from that structure's ground/neutrals, but it is in a multi gang box so I must tie all the grounds together.
 
electrofelon said:
the circuit in question is a three way switch between the two structures - fed and loaded at the same structure - thus I dont see any issue with the one source requirement.
Agreed, according to 225.30(D).

electrofelon said:
The potential code/safety issue I see is with neutral current flowing on the switch circuit egc between the two services?
If this does happen, then I'd say you should exercise your option presented by 250.6(B)(1), and have the EGC provided with the travellers bond the metallic components of the electrical system associated with that system. Until you measure any objectionable current, I'd say 250.148 is requiring you to connect the EGCs.

I'd avoid using a crimp sleeve in that box. ;)

Another oddity about your situation: I'd say you need a disconnecting means for the travellers, and it would need to be grouped with the other supply, 225.34(A). A DPDT toggle switch in a bell box would probably suffice.
 
I have a hard time believing you could put it in the same multi-gang box as wiring from the other building... we always have to keep them seperate. Same problem occurs in multi-unit offices and apartment buildings with mulitiple services.
 
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I like the options provided in 250.6. It seems like it is up to me to meter the egc and decide if there is objectionable current flowing on it. I also sould prefer to have this switch in it own isolated box, but in this case I think it needs to be ganged.
 
DaveTap said:
I have a hard time believing you could put it in the same multi-gang box as wiring from the other building... we always have to keep them seperate. Same problem occurs in multi-unit offices and apartment buildings with mulitiple services.

What code rule forces you into that?
 
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