Take the 2-minute tour ×
Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It's 100% free, no registration required.

I have a home standby generator that is equipped with a GFI, and my original electrician (who has long since flaked out on me leaving me in a lurch with this) installed a standard 2-pole transfer switch rather than the required (according to the generator manual) 3- or 4-pole neutral switching switch. So I am now left with a working generator and completely wired transfer switch, but they won't work together as the GFI on the generator trips immediately upon starting when it's connected to the house (though it works fine with an extension cord).

Besides spending a ton of money all over again to get a 3- or 4-pole switch installed is there anything I can do to get this to work?

I've read about possibly not grounding the generator a second time here, but I'm not exactly sure what that means or if it is safe. I've talked to 2 other electricians about this and so far no one seems to have a clue.

share|improve this question
add comment

1 Answer

up vote 3 down vote accepted

This site seems to have a decent explanation:

Some portable generators are intended for use on jobsites, and therefore are subject to OSHA regulations for GFCI protection on all receptacles. These "contractor grade" generators have their neutral wire bonded to the ground wire to pass OSHA inspection on job sites. Since home and building main load centers also have the neutral bonded to ground, a loop is created, comprised of the neutral wire and the ground wire. A small amount of current is induced in this loop by the running generator. and since the neutral wire passes through the ground fault sensor, the GFCI senses this induced current and trips the main circuit breaker in the generator.

When using these neutral bonded generators to power a house or building through a transfer switch, the neutral bond wire on the generator must be removed, preferably by a dealer or a qualified electrician. NOTE: After this action, the generator will no longer pass OSHA inspection on job sites. Contact your dealer to determine if the neutral bond can be removed, and we recommend that a dealer perform this task. Honda dealers may refer to Honda Service Bulletin #20 for instructions on removing the neutral bond. Once this is done, no modifications to your transfer switch installation are needed.

If the neutral bond cannot be removed, you have two choices. The easiest solution is to lift the ground wire coming from the generator inside the transfer switch, and secure it with a wire nut, by itself. This eliminates the loop. Your other choice is to install a Switched Neutral Kit (SNK) accessory with your transfer switch, available thru our website.

Note that the generator is still grounded, it's just the neutral bond is gone. This means that the generator does not meet code for stand-alone operation anymore.


So your options are:

  • Install a switched neutral kit
  • Change to a neutral-switching transfer switch
  • Remove the ground-neutral bond from your genset

Here's the instructions on how to do this for Honda generators: http://www.gen-tran.com/assets/pdfs/HondaGeneratorServiceBulletin20.pdf

Here's another good site that explains the issue and how to fix for several other generators: http://members.rennlist.org/warren/gt5000c.html

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.