Two electrical services and one common generator(Possible Neutral issue)

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rioslives

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My question is really about switching the neutrals on a two service one generator installation.
Will the neutrals need to transfer before the feeders to limit arcing? Or could I use a three phase ATS on a single phase service and use the third pole to switch the neutral? My fear is if the neutral ever disconnects on the utility side it will back feed through the neutral of the second service. Two service one generator is very common lately in my area and I want to cover all the bases and do it correctly.
Thanks
 
rioslives said:
My question is really about switching the neutrals on a two service one generator installation.
Will the neutrals need to transfer before the feeders to limit arcing? Or could I use a three phase ATS on a single phase service and use the third pole to switch the neutral? My fear is if the neutral ever disconnects on the utility side it will back feed through the neutral of the second service. Two service one generator is very common lately in my area and I want to cover all the bases and do it correctly.
Thanks
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You will need a 2 pole switch with switched neutral, not a 3 phase switch. There are various control and other differences between the two. Note that this will pretty much rule out using a resi grade ATS as you won't find one with a switched neutral.
I don't see any need for overlapping neutrals switches.
There may be some legal or code (not NEC) issues unless both services are on the same property and owned by the same person. Might want to check with your building official.
I do think that you are correct switching the neutral is required for NEC compliance.
 
Consider a switch which breaks (and verifies) the phases before switching the neutral and then connects the new phases.
Such ATS devices are commercially available.

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Would you happen to know the code section that pertains to switching the neutral? I can't same to find it. Thanks for the help.

texie said:
You will need a 2 pole switch with switched neutral, not a 3 phase switch. There are various control and other differences between the two. Note that this will pretty much rule out using a resi grade ATS as you won't find one with a switched neutral.
I don't see any need for overlapping neutrals switches.
There may be some legal or code (not NEC) issues unless both services are on the same property and owned by the same person. Might want to check with your building official.
I do think that you are correct switching the neutral is required for NEC compliance.
Click to expand...
 
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