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bradeng 12-08-2008 10:10 PM

Generator and Neutral Bonding Issue
Ok I have installed a Briggs & Stratton 7kw (model 040248) stand-by generator and a 16-circuit SIEMENS 2-pole manual transfer switch. I installed everything and once I fired up the generator and plugged into the 240 outlet the 30A GFCI breaker on the generator tripped and subsequently each other time I tried. After playing with it I noticed that if I disconnected the ground from the 4-wire cord going into the disconnect box on the outside, the generator would run and provide power to the house.

I then came in and did some research last night and found that the generator and the transfer switch are by code not compatible as the generator's Neutral is BONDED to the chassis, and technically you would need a transfer switch to "switch the neutrals". Well after a large investment in money and time and no way to take anything back, I am in search of a solution.

One thing I came across was that I can "REMOVE THE BOND" on the generator and everything should work because it would bond to the main panel in the house.

My ultimate question is if this the direction I should take? Are there any other alternatives? If this is the direction I need to go how do I effectively un-bond the neutral on the generator. I have included a link to the "WIRING DIAGRAM" below for assistance. I also have opened up the control panel on the generator and found a screw through the chassis in the back with 4 wires under it (2 white and 2 green), do I remove the whites from the bolt and tie them together and I am done or what are my options.

Also Manual of course says DO NOT REMOVE BOND as GFCI OUTLET WILL NOT WORK AND CAN CAUSE INJURY, but if everything flows down through to the main panel will the GFCI still not work?

I am new to this forum and I thank you in advance for any help.


Gigs 12-08-2008 11:05 PM

The GFCI should still work. A GFCI does not require a ground to detect a current imbalance.

What you have going on there is the bonding between neutral and ground at your main panel is causing current sharing between the incorrectly bonded neutral and ground at the generator.

I'm not sure why they would do something that stupid. It might be good to try to figure out the reasoning behind it.

To confirm the GFCI still works, you can either buy a GFCI tester, or make one if you have a few resistors laying around.

InPhase277 12-09-2008 01:12 AM

The bond can be removed and indeed has to be removed if you want to use this generator in this application. But the bond exists to ground the frame of the generator in stand alone use. So, if you intend to only use it while connected to your house, then disconnect it, but if ever use it as a portable then you need the bond connected. Perhaps you could install a very visible switch that connects and disconnects the bond for different applications.

bradeng 12-09-2008 07:27 AM

So if I remove the white neutral wires do I leave the green ground wires under the bolt which is bolted to the chassis?

AllanJ 12-09-2008 08:30 AM

The ground (green) wire bonded to the chassis (via the bolt) remains in place there.

bradeng 12-09-2008 10:13 AM

Ok, I UNBONDED the neutral wires and bolted them together by themselves with tape. Generator fired up and ran with no problems. I pushed the TEST button on the GFCI breaker, and the breaker tripped. So this means that the GFCI IS working CORRECTLY and being bonded down at the main panel in the house?

InPhase277 12-09-2008 10:24 AM

Yes, most likely. Buy a GFCI tester and use it on a standard outlet in your house while it is being powered by the generator. Or create a ground to neutral short with a jumper wire and see if the GFCI operates.

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