Plan Review sumittal showed a 800a SUSE rated Transfer switch including overcurrent protection located about 10' from the xformer and generator. The Service point is at the Transfer switch. The building it will be serving is located about 150' away. Question is- What should I expect to see as the Grounding Electrode for the Service?? And, should the contractor run an EGC with the feeder to the building?? There is a water pipe electrode located in the building. Next Question- Do I have to float the neutral??
I don't know if the standard, consisting of metal post and cross members is considered to be a structure.
Your comments are invited
[This message has been edited by George Little (edited 02-20-2005).]
If I am reading the question correctly, I think a question that should be asked is, "Is the transfer switch breaking the neutral conductor?" If so, then the Gen. is a Seperatly Derived system. If not, then the transfer switch and equipment can use the grounding from the original building.
Harold- the issue is whether to run a EGC with the feeder to the building. Greg says "No" and I agree. If we run an EGC then we would have to float the neutral in the building. If we don't, then we can use the Grounding Electrode in the building (water pipe and supplement) and run a GEC to the electrode and Bond the Neutral in the building.
At the Transfer Switch I haven't addresed the breaking of the neutral since it's not part of the problem. The neutrals of both systems are using the same bond screw and Grounding Electrode of the transfer switch.
The opposing view on this subject is that the water pipe electrode in the building because it is "available on the premises" must be used and connected to the Service Disconnect/transfer switch located remote from the building.
[This message has been edited by George Little (edited 02-21-2005).]
George 250.32 If theres any parallel path on the neutral such as (metal conduit, Gas or fuel lines, water lines, Control wires(generator) ect .Then the fourth (gr) wire is required And Float neutral in the Dn. stream Panel.
Yooper- There aren't any parallel paths. And I think that we'd have to consider the assembly (Transfer/Service Disconnect switch and Generator) at the remote location as a "structure" for us to be able to for go the EGC. I still like Greg's approach.
If available on the premises "at each building or structure" is what 250.50 states. You wouldn't use the water pipe electrode at the building 150 feet away for the structure supporting the service rated transfer equipment.
I would say that you are allowed to bring either a 3 wire, or a 4 wire with EGC to the building, but the 4 wire would require that you float the neutral at the building. In either case, a electrode will be established at the building and at the structure for the service.
Also the building will need its own disconnect and it must be suitable as service equipment.
OK, how about this one. If you run 3 wires from the house to the out building (We can call this a sub service) then you have to bond the neutrals and ground together in the out building. If you run 4 wire out to the out building (We can call this a sub panel type) then you would isolate the neutrals and grounds in the sub panel in the out building. This would be OK as long as there was no parallel paths. (Which you said that there isn't any.) So I feel that you could bring either a 3 or a 4 wire out to the out building. Your choice.