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joemoor
Oct 26, 2006, 07:07 AM
This should be a straightforward question and answer but so far everyone I've asked has given me the "it's a local code issue" or in my opinion the wrong answer.

I have a 12KW standby generator permanently installed at my home. The ATS is a two-pole transfer with a solid neutral. The generator set is shipped with neutral bonded to ground via a terminal stud on the frame. The instructions say to "lift" the neutral to un-bind it. I've spoken to the distributor of the generator and they said that is the proper procedure. Basically I would connect my main neutral from my ATS to the two neutrals coming from the alternator and tape them off so they do not come in contact with the frame.

I've had the electrician who is helping me tell me that the neutral should stay bonded to ground and the generator equipment ground should be bound to my service ground. Everything else I have read says that since this is NOT a SDS the neutral and ground from my ATS should remain independent so that I only have my N-G bond at the service entrance.

I have four wires from my ATS to generator H-H-N-G and the neutral is NOT switched. The setup my electrician suggests would bond N-G in two places since the neutral is solid.

My AHJ is only part-time in my town (rural area) and it's difficult to get in touch with him other than inspection time.

Thanks

bhayne
Oct 26, 2006, 09:54 AM
The neutral is a current carrying conductor. The ground is not.

The ground is attached to the case of the ATS and to the generator frame. You are correct, the neutral from the ATS should be taped off at the generator so that it does not come in contact with the ground.

Ideally, the only place that the neutral and ground are connected is at your main panel.

cve
Oct 26, 2006, 12:16 PM
There is a bit of confusion about generator grounding.
My understanding is that G and N must be separated from main to ATS. I would think of it as sub panel.
However I believe the gen. manufacturers require a ground rod at generator.
Not sure what good this does though.

tkrussell
Oct 26, 2006, 12:20 PM
Bhayne is correct, see a previous post:
https://www.askmehelpdesk.com/electrical-lighting/transfer-switch-33435.html?highlight=generator


EDIT:

A genset must be grounded with a rod if is it a SDS, or if the manufacturer recommends.

joemoor
Oct 26, 2006, 12:42 PM
Thanks everyone for affirming my solution. I've also found a great document put out by Schneider Electric. It's based on the CEC but the same principals still apply.

http://www.schneider-electric.ca/www/en/products/stab-lok/Gen_Panels_Appl_Note_EN.pdf