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#203693 - 10/19/11 07:51 PM manual transfer switch and neutral
Niko Offline
Member

Registered: 08/17/06
Posts: 358
Loc: Campbell, CA
I don't quite understand when/why the neutral needs to get switched when a generator is involved in a residential system. Can you explain please.

i am installing a manual transfer switch but am wondering if i need to switch the neutral as well?

Thanks
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#203696 - 10/19/11 10:27 PM Re: manual transfer switch and neutral [Re: Niko]
ghost307 Offline
Member

Registered: 05/09/05
Posts: 876
Loc: Chicago Illinois USA
The electrical system needs the neutral to be grounded at 1 and only 1 point.

If both your normal Service and your generator have grounded neutrals, when they are connected together you will have the neutral of the system grounded at 2 points, which is a no-no.

If your generator neutral is grounded, you need to switch the neutral; if your generator neutral is not grounded, you can allow it to be connected to the normal system's ground via the system's neutral.
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#203697 - 10/19/11 11:44 PM Re: manual transfer switch and neutral [Re: Niko]
Niko Offline
Member

Registered: 08/17/06
Posts: 358
Loc: Campbell, CA
Thanks Ghost,
they (the customer) will be installing a portable generator until a permanent one can be purchased.

Are neutrals usually grounded on the portable units? or it varies? and if it is grounded can i disconnect the neutral from the generator frame? Or i am messing up the listing?
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#203698 - 10/20/11 12:48 AM Re: manual transfer switch and neutral [Re: Niko]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9012
Loc: Estero,Fl,usa
There is usually a comment in the instructions of how to lift the bond in the generator if you are making this a non-SDS.
(not switching the neutral). I think Hondas come floating and most others are bonded from the factory.
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#203703 - 10/20/11 07:32 AM Re: manual transfer switch and neutral [Re: gfretwell]
KJay Offline
Member

Registered: 11/27/07
Posts: 763
Loc: MA, USA
Iíve never switched a neutral on a resi transfer switch, whether automatic or manual. I just make the appropriate change to the ground connection at the generator itself.

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#203705 - 10/20/11 08:07 AM Re: manual transfer switch and neutral [Re: Niko]
Niko Offline
Member

Registered: 08/17/06
Posts: 358
Loc: Campbell, CA
OK. Thanks.

i think now my question turns to SDS. why would would someone choose not to remove the neutral. or any advantage of SDS or non- SDS?

i know the definition of SDS but i dont think i have a 100% grasp as to why you would have one or wouldn't.
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#203707 - 10/20/11 09:39 AM Re: manual transfer switch and neutral [Re: Niko]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9012
Loc: Estero,Fl,usa
I can't think of any good reason to create an SDS in 120/240v systems. Usually you apply this when you would be changing from delta to wye or some other significant system change.
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#203708 - 10/20/11 09:41 AM Re: manual transfer switch and neutral [Re: Niko]
sparkyinak Offline
Member

Registered: 07/08/07
Posts: 1286
Loc: Alaska
Check with your POCO. a few years ago, I saw a commercial for another POCO and they had a shot on a xfer switch and wasn't switched. I contacted them and they said they didn't want the neutral switch
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#203710 - 10/20/11 09:43 AM Re: manual transfer switch and neutral [Re: Niko]
Niko Offline
Member

Registered: 08/17/06
Posts: 358
Loc: Campbell, CA
OK thank you for the replies.
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