# GFCI on generator tripping; home backup



## Yoyizit (Jul 11, 2008)

http://159.105.83.167/Portals/0/WP Safety/Portable Generators qnd OSHA Construction Standards22.pdf

?

BTW, 900' of perfectly good Romex will probably have enough inter-conductor capacitance to give you 4 mA of reactive leakage current and so would validly trip a GFCI. 
If it is the Romex the fix would be to have the gen. only run sections or only specific appliances/fixtures in your house.
I suppose you could check this by running the generator with almost all breakers off in your house. Turn them on one by one until you trip the GFCI. If the thing trips with all breakers off the problem almost certainly has to be elsewhere.

You could also check the leakage current of the wiring in your house. Put a 7-1/2w incand. lamp in series with the ground wire that serves the cable downstream of your GFCI. If the voltage across the bulb reads from 0.6 vac to up to 120vac you've found your leakage path to ground. A normal reading would be less than 15 mVac. Disconnect chunks of the cable or appliances until the leakage current goes away.


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## kbsparky (Sep 11, 2008)

The problem of GFCI tripping is that the service panel that you are backfeeding already has its neutral conductor bonded to the grounding conductors.

If these conductors are separately monitored by an integral GFCI device in the generator, it will trip out as soon as you plug it in, _even with the interlocking breakers switched off._

Some generators have instructions on how to configure when used as a stand-by power source for a home.

What brand and model number are you dealing with here?


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## Speedy Petey (Feb 1, 2004)

Are you saying the 120v GFI is tripping?
If you are trying to connect your panel to the 120v 20A receptacle on a generator this is a VERY flawed plan. You should be using the 120/240v receptacle on your generator which is not GFI protected.
Your electrician should have know this.


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## micromind (Mar 9, 2008)

As stated above, almost certainly the generator neutral is bonded to the ground. So is the house. You'll need to remove the bond jumper in the generator. 

Also as stated above, it'd be a huge waste of generator capacity to use a 120 volt receptacle to power the house. You can only get 2400 watts through a 20 amp 120 volt receptacle. 

Some generators have two pole GFIs though, if the cord that plugs into the generator has 4 prongs on it, then it'll deliver full power to the house. But you'll still need to remove the bonding jumper. 

In no case remove the bonding jumper at the house panel. If you do, you'll have no ground-fault protection when on utility. 

Rob


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## Scuba_Dave (Jan 16, 2009)

Yoyizit said:


> http://159.105.83.167/Portals/0/WP Safety/Portable Generators qnd OSHA Construction Standards22.pdf
> 
> ?
> 
> BTW, 900' of perfectly good Romex will probably have enough inter-conductor capacitance to give you 4 mA of reactive leakage current and so would validly trip a GFCI.


Did I miss something?
Where does it say the Gen is 450' away from the house?
That would be 3 houses away for me :laughing:


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## MrNeutron (Jul 1, 2009)

Thanks everyone for the quick replies. The generator is a Wacker Neuson GPS6600A and I'm using the 12/240v receptacle. 

I posted here because I wasn't hearing from the manufacturer. Wouldn't you know, they just replied tonight. Looks like bond or ground jumper is the issue. Below (in italics) is the reply I got from Wacker Neuson.

Thanks for the guidance. It looks like I'm on track now.


_The neutral - ground jumper wire on the generator will have to be_
_removed to prevent the nuisance tripping of the GFCI._

_Your house should already have its neutral bonded to ground so this_
_still meets requirements of the National Electric Code (NEC)._



_Your Wacker Neuson dealer can sell you a kit p/n 0164835 that contains_
_these instructions and stick-on labels that warn the generator now has a_
_floating neutral._



_NOTE: If you ever disconnect the generator from the house and use it for_
_other purposes, you MUST re-connect the neutral - ground jumper on the_
_generator!_

_If you (or the next owner of the generator) do not intend to re-connect_
_the generator to the house again... then you may also remove the_
_floating neutral labels._


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## Cow (Jan 5, 2008)

Exactly how many generators has this guy wired to not know there is a neutral-ground bond that needs to be removed in the generator. I just don't get it.:whistling2:


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## Yoyizit (Jul 11, 2008)

Scuba_Dave said:


> Did I miss something?
> Where does it say the Gen is 450' away from the house?
> That would be 3 houses away for me :laughing:


Nah, I think the average house has more than 900' of Romex in it and all that distributed capacitance adds up. 
I'm going to fire my ghostwriter!

To the OP: you know, there is an implied warranty of merchantability and an implied warranty of fitness. Your electrician must have known what your intention was in buying this generator. Your State's Attorney may persuade the guy to make this right.


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## micromind (Mar 9, 2008)

In my experience, very few electricians know about neutral bonding of generators. This includes small home-style generators all the way up to huge ones that would run half a city. 

Neutral bonding is not all that difficult; in the end there can be exactly one. No more, no less. 

With a generator, if the transfer switch doesn't transfer the neutral, the generator cannot be neutral bonded. If it does transfer the neutral (rare, but required in some cases, like hospitals), then it must have its neutral bonded. 

Very few people, even electricians with lots of experience, and a multitude of electrical engineers, understand this. 

Rob


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## AndrewF (Dec 29, 2008)

MrNeutron said:


> . . . 6600 watt generator for power backup.. . . How do I use this brand new $2,200 generator to power my house. . .


Did you really spend $2200 on a gas 6600 watt generator? Wow, someone made a profit.


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## Speedy Petey (Feb 1, 2004)

AndrewF said:


> Did you really spend $2200 on a gas 6600 watt generator? Wow, someone made a profit.


Maybe it's not a piece of crap. :whistling2:


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## kbsparky (Sep 11, 2008)

If its an 1800 RPM unit, worth every dime. :wink:


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## AndrewF (Dec 29, 2008)

kbsparky said:


> If its an 1800 RPM unit, worth every dime. :wink:


True, I didnt check the specs and would agree. If it is a 3600 RPM...then no.


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## KeithM62948 (Jun 10, 2009)

I think it's sweet of the manufacturer to sell you a 'part' that contains nothing but instructions & labels!


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## MrNeutron (Jul 1, 2009)

Thanks for everyone's concern for my financial well being!  I actually found it on craigslist and paid $1200. The guy I bought it from paid $2200, or so he said but my research indicated he probably did. Apparently he was liquidating some assetts. The whole thing seemed sketchy but I checked the serial with the manufacturer and the seller's story checked out. I figured it was a good deal for a quality unit with a Honda motor. 

I agree that the kit consisting only of labels is a bit ridiculous. Anyone want to sell me some duct tape and a sharpie? The manufacturer did send me the instructions electronically. So, I'm satisfied. It looks like a pretty easy job.

Thanks again for the feedback everyone!


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## Scuba_Dave (Jan 16, 2009)

Yoyizit said:


> Nah, I think the average house has more than 900' of Romex in it and all that distributed capacitance adds up.
> I'm going to fire my ghostwriter!


Ah, I see - learn something new every day


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## Yoyizit (Jul 11, 2008)

MrNeutron said:


> The generator is a Wacker Neuson GPS6600A


While I have your attention, does 5.2 gals of gas in this generator give you 60 kwh? More? Less?


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## MrNeutron (Jul 1, 2009)

Yoyizit said:


> While I have your attention, does 5.2 gals of gas in this generator give you 60 kwh? More? Less?


 
Not Sure. Here are the specs. Maybe you can tell me.
http://products.wackerneuson.com/we...ay?storeId=10051&partNumber=0620386&langId=-1


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## Yoyizit (Jul 11, 2008)

MrNeutron said:


> Not Sure. Here are the specs. Maybe you can tell me.
> http://products.wackerneuson.com/we...ay?storeId=10051&partNumber=0620386&langId=-1


I couldn't log in. 
At $2.50/gal for gasoline you'd be paying 21 cents per kwh. It's got to cost more than this. . .people in Hawaii pay this much for commercially generated power.


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## MrNeutron (Jul 1, 2009)

*3 pole vs. 2 pole transfer switch*

I wonder what everyone thinks about this. I asked the tech support folks at Wacker Neuson if there is a way to disable the GFCI for the 120/240v receptacle while leaving it enabled for the standard three prong 120 recptacles. Their answer is below. My questions are 1) is a three pole transfer switch really safer and more efficient? and 2) is there any downside to running a generator that doesn't have a GFCI on a three pole switch? Your thoughts?


1)The reason the GPS6600A GFCI trips when you connect to the transfer switch on your house is because your electrician installed a two pole transfer switch.
Two pole transfer switches are very common and economical.
However, a two pole transfer switch only disconnects the two “hot” wires. The generator neutral is hard wired to the neutral wire on your house.
When the generator neutral is always connected to the house neutral and both neutrals are bonded to ground… you get a ground loop circuit which trips the GPS6600A GFCI (as it should) A ground loop wastes power and may actually energize the GPS6600A frame!

2)The best solution to your application is to have your electrician install a Three pole transfer switch.
A three pole transfer switch disconnects the two “hot” wires + the Neutral wire. This eliminates a ground loop circuit.
Then nothing has to be changed in the GPS6600A, the GFCI module still provides full protection, and you can power other things like hand tools etc.

3)If you must use the two pole transfer switch…then you MUST open the neutral-ground bond in the GPS6600A.
When the GPS6600A is connected to your house, you will not have GFCI protection at any of the other generator receptacles.
If you desire to use the 120V duplex receptacles on the GPS6600A, then you need to plug in a power cord with a built-in GFCI module 
(check hardware, electrical, or contractor supply stores). 
A plug-in GFCI will still provide protection when the generator neutral-ground bond is open (floating neutral).


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## micromind (Mar 9, 2008)

Their instructions are exactly correct. A 3 pole transfer switch will transfer the neutral as well as the phases. (See post #10). If you go this route, the transfer switch must be installed downstream of the utility service bond jumper. The generator must then have its neutral bonded to ground.

If the neutral bond is disconnected in the generator, nothing connected to the generator is GFI protected. If you use the generator somewhere other than to power the house, you should provide some sort of GFI protection. The pigtail GFI cords described in the instructions will work, but you need to remember to use them. 

If possible, replace the 120 volt receptacles in the generator with GFIs. That way, protection is built-in. If not, the pigtail GFIs might be the best bet.

Any type of GFI will provide protection whether the neutral is bonded of floating.

Rob

P.S. There are plenty of portable generators rated 5000 watts or less that have no GFI protection at all. I don't get it.... it only takes a couple of watts to kill a person.


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