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Portable Inverter Generator Neutral Ground Bonding Plug Honda Yamaha

Portable Generator Neutral Ground Bonding Edison Plug NGB With the recent bad weather back east my email inbox has been filled with all sorts of questions regarding portable generators, transfer switch wiring, powering furnaces, well pumps etc. One of the big problems people are having is with the newer inverter type generators, the Honda EU series and the Yamaha and countless others like them. The issue is with powering certain equipment and electronics the generator shows a ground or reversed polarity fault and won’t work.

The problem is that these generators use what’s called a floating neutral or unbonded neutral/ground. Standard wiring in a home has the Ground and Neutral Bonded together usually at the Circuit breaker panel or distribution center.

So for example you have a (HE) High Efficiency Furnace that is wired through a transfer switch, using your Honda EU2000 generator won’t run it but you have an older Coleman generator and when you hook that up it works just fine.

The Honda EU2000 isn’t providing the Ground-Neutral Bond that your HE Furnace requires… to think it’s getting properly grounded power, while your Coleman generator has a Ground-Neutral bond already so it operates your HE Furnace properly.

Now sometimes this can be alleviated by making sure you have everything wired properly, sometimes simply not switching the neutral wiring in a transfer switch will accomplish this as well. Other times you simply have to create your own Neutral-Ground Bond. In the past Honda put out a Service bulletin on G-N Bonding and rewiring the generator head itself, and others have done this too but I don’t recommend it for one you’ll ruin your warranty and could cause other problems not to mention the risk of shock or fire.

The easiest way to do a N-G Bond is to create a N-G Bonded Edison Plug, this is done by simply buying a replacement male plug and wiring the Neutral (White Wire/Silver Screw) to the Ground (Green Wire/Green Screw) using a 12-14 Gauge piece of wire. Just make darn sure you don’t wire the Hot leg tot he ground. Then when you need to power something like a RV or HE Furnace with your generator you plug it into a empty outlet.

Make sure you label this plug specifically for its purpose. It won’t really do any harm to anything if it’s plugged into a correctly wired home outlet, but it will create a secondary G-N bonding point that could induce ground loop currents and create hum or buzz in a sound system.

I hope you found this information helpful, as with all electrical work be careful and sure of what your doing, and verify all information before attempting to rewire or override a safety device, and never remove the Ground Neutral Bond from a bonded generator.

I’ll post an update on how to check your generator to see if it has a floating or bonded neutral.

18 comments

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  1. Yuval

    Hi Rick,
    First of all, thanks for a great and informative website!
    Up here in Toronto we’ve had a nasty ice storm back in December which caused my house to go without power for 3 days. I since started looking into powering my gas furnace using an inverter connected to my car battery. I got a “Motomaster Eliminator” 1KW pure sine wave inverter (model 011-1892-4), had it wired with 3 AWG wires to my car, and using a 14 AWG extension cord was able to power a variety of tools up to 1KW without a problem. But when wired to my gas furnace I received a “Reversed 115 VAC Polarity / Verify GND” fault.
    Surfing the web led me to your site, where I read about floating neutral inverters and the need for neutral/ground bonding. I verified my inverter is indeed floating neutral.
    So now to my questions –
    First – how do I bond neutral and ground on my inverter? As far as I understand, both left and right legs on floating neutral inverter are hot? Or am I wrong?
    Secondly, on newer inverters, the receptacles are GFI (meaning if I short neutral to ground I’ll trip the breaker), but I guess on my model the receptacle’s not GFI since they don’t have that test button that GFI receptacles normally have.
    Thirdly – I understand there needs to be just one neutral-ground bonding in the circuit. Can I bond neutral to ground at the point where I connect the extension cord to the gas furnace?
    Fourth and last – Do I need to also ground the inverter to a metal rod?

    Lots of questions, lots of confusion, hope you’re able to sort it out for me, thanks!

    1. Rick

      Hi, well sounds like allot of people have the same problem, and as you noted if you check with a volt meter from ground to the hot and ground to neutral you will probably find roughly 60 volts, this is common and it makes these type of inverters cheaper to make. Answer#1; With that said most inverters can’t be wired internally to have a bonded neutral. You will have to do it outside of the inverter either at the plugs with a ground neutral plug as I have posted about here.

      Answer#2; I have not played with any of the GFI inverters, but I’ve had an extension cord with a GFI built in and it seemed to work fine powering a deep freezer.

      Answer#3; yes legally speaking and safety speaking it’s best to have only one source of ground so in a fault the current dumps through one source. I usually recommend to try just grounding at the furnace and see if that works, if you keep all the grounds connected to the main house ground. You could also try connecting the neutral wire to the ground at the furnace and try that, but it’s easier and safer using the adapted ground neutral plug at the inverter.

      Answer#4; It depends, if your running the inverter as a completely separate circuit where in no way (ground) ties in with your house system then I would ground the inverter. A meter long should suffice for a ground rod, copper, steel…it doesn’t matter and at least a 14awg wire to each.

      I honestly would try the plug first and see if that does anything, I’ve yet to hear from anyone that they can’t make it work but eventually there will a inverter out there that doesn’t like that and cannot be made to do what we want….Good luck…wear gloves:)

      1. Yuval

        Thanks Rick, will definitely give the plug a try first.
        If it works i’ll want to install a transfer switch. Will your transfer switch take care of neutral/ground bonding or will I still need to have the bond at the plug connected to the inverter?

  2. Yuval

    Success! after bonding neutral and ground at the plug going into the inverter, the furnace works perfectly. Thanks or the tip :)

  3. Steve

    Hello Rick,
    I have been looking for a fix to my problem for well over a month now. I’m not at all familiar with most of the terms that I’ve found on your web site but you sound like the guy with the answer. I have the opposite problem with my generator. It operates everything except the 3 year old high efficiency Lennox furnace that I have installed in my home. The generator is an ETQ5250 (company has since closed) with the capability of providing 120V or 120V/240V. I use the available 120/240 receptacle (L14-30R) and a matching L14-30P plug which is wired to a transfer switch located beside the main electrical panel. The 240V is needed to operate my deep water submersible well pump. As I said, everything wired to the transfer switch panel works just fine (well pump, sump pump, sewage lift pump, on demand water heater, fridge, freezer, several receptacles, etc.) except for the furnace. The first thing that I was told is that I needed an inverter type generator which produces “clean power”, preferably a Honda or Yamaha. To test the theory I rented a 2000W Honda and wired it directly to the furnace. It worked perfectly through all stages (speeds) of the blower. Although one might think problem solved I’m looking for a cheaper fix than the $5,500 I would need to pay for a new Honda with 240V capability and an L14-30R receptacle. I could buy a second 2000W Honda inverter generator ($2,500) and install one of your “Simple EZ Generator Transfer Switch for a Single Circuit Appliance” but having one generator, which is already wired to a transfer switch, is much more convenient and safer. I read your comments regarding the Ground-Neutral Bond issue but I don’t understand it in the least. Also, my issue is opposite …. my furnace works fine with a Honda EU2000 generator. Please help Rick … we get -40 degree temperatures up here in Northern Ontario and lots of power outages.

    1. Rick

      Hi Steve,

      Sorry I thought I replied to this but it looks like I saved it as a draft, here’s my answer.

      Steve, Sounds like the problem your having is from the ground neutral bond most likely. Your ETQ generator must have a bonded neutral, meaning the ground and the neutral are connected together electrically…this is quite common I would say 75% or more generators are like this…there are ways to make this floating but without being able to contact ETQ directly you might not be able to know what to do. Honda had put out a bulletin several years back on doing it to their older generator sets. The Honda EU series use whats called a floating neutral/ground bond. Either you could try and see how to disconnect this neutral/ground bond internally on the generator (there are some videos online) or maybe try and trade your Generator for a Honda plus cash maybe? Not really allot of options here…Good luck.

  4. Mike

    Hi Rick,

    I have a Lennox high efficiency heater which is reacting like your various posts. Blower works but gas does not ignite by glow plug. Is there a brand of generator that I can buy that will just work without extension cord modifications etc?

    Thanks so much for your help

    1. Rick

      Hi Mike, It really all depends on the wiring I try not to recommend a particular one because something might change.

  5. Ken

    Just purchased a Champion 2000 watt inverter generator. Installed socket outside the house and ran 12/2 wire to a Reliance 30 amp, 4 circuit transfer switch. Got everything wired up and plugged in the generator. The transfer switch circuits were set to LINE. After plugging in, the generator immediately revved up and tripped. After much trouble shooting I ended up pulling things apart to see if I could isolate the cause. When I disconnect the transfer switch from the supply line I found that a light would work just fine. This was off the line feeding the transfer switch. Hooked the line back to the transfer switch and left the ground and neutral from the generator hooked into my panel. Removed all other lines from the panel. Fired up the generator and it immediately tripped. I have found just hooking the neutral to my panel makes the gen trip. No other lines are connected to the panel other than then neutral. The panel is neutral bonded and the generator is floating neutral. What the heck would cause this to happen?

    1. Rick

      Hi Ken, First I will say that I have heard many issues with using a inverter type generator and powering through a transfer switch. The inverter ones usually have a GFCI breaker, this I think is where your having problems. The floating neutral thus being bonded/grounded in your panel is causing the fault and it shuts down, this is normal operation as it see’s this as the neutral has failed and is grounding itself.

      The floating neutral can’t be grounded. The only real remedy is to not use that transfer switch, it’s one of the main reasons I started making my own transfer switches. I couldn’t buy a small transfer switch that switched the neutral, the Generac, Reliance and other transfer switches only switch the hot leg of power. Which is fine for older style generators but many of the new ones are having issues. Might want to give Reliance a call and see if they have another solution that I’m not thinking of.

      1. Ken

        Thanks a bunch Rick. Should have talked to Reliance before buying this switch. Lesson learned. I’ll see what Reliance has to offer and hope I can exchange my transfer switch.

        One more question if you don’t mind. If I go the route of not using the switch and just power my TV, pellet stove, lights, etc off the generator will I need an N-G bond? If I am ready this thread correctly it sounds like I should at least ground the generator via a rod stuck in the ground.

        1. Rick

          Ken, For the other equipment you shouldn’t need the NG bond, if your running the extension cord directly to that equipment. I would think those should run fine, I would try and ground it if you could as it doesn’t take much to do this. Cheers!

  6. Dustin

    Hi Rick,

    I just bought a LPG generator from the local big-box chain, it only has two 120v ‘plugs’. I am leaving on only the breaker of circuit that I’m plugging the generator into and the breaker of the furance. Both are on the left side of the panel. When I backfeed through a plug into my main box in this condition, all my lights will work, refrigerator, etc, everything but the 95% Goodman furnace, which will not turn on the fan nor ignite.

    My furnace has a receptacle and switch mounted to it. And the receptacle is upstream of the switch, meaning the switch does not toggle on/off the receptacle, only the furnace downstream of it. When I plug the generator directly into this plug (and leave the switch on, of course) the furnace runs beautifully.

    Ideally I would like the furnace to run while the entire house is backfed, but I dont understand why the furnace runs when fed directly by the generator, but not by the generator through the house main panel.

    Its a 4000w generator, and the furnace fan only draws 8A at startup (less while running), so I dont think the problem is related to load.

    Thank you for any insight.
    Dustin

    1. Rick

      Hi Dustin, While I can’t approve of your method of backfeeding the issue is probably the layout of your panel. The loads alternate, there not just on the left or right. They alternate from even to odd if that makes sense. So say your feed is on #1 the top left, that will also feed #2 on the right, #3 which is under #1 is fed from the other side if you will. So If you feed on #1, you are actually powering every other Odd/Even #1,5,9,13,17,21 etc and #2,6,10,14,16,20. You probably just need to move the location of your incoming feed or the furnace breaker up/down one. Hope that makes sense, If you look at some pictures of the inner part of breaker panel it will make more sense. Be safe.

  7. Kelly

    Rick,

    Your video was really helpful, thank you. Like others I’m in the boat of trying to run my gas furnace from an inverter generator with a floating neutral. My question is whether there is any alternative to the neutral ground bonding plug you suggest. In my case, I have two small inverter generators. One has only ONE 120 volt outlet. If I plug the bonding plug into the outlet there would be nowhere to plug in anything else. The other inverter is a Yamaha ef2000 and has two 120 volt outlets, so technically on that one the bonding plug could be plugged into one outlet and the extension cord for the furnace into the other — however, that is not idea for my setup as I would like to use BOTH outlets for extension cords. Can you suggest another way of accomplishing the the neutral ground bond? Is there a away to wire the extension cord itself to accomplish the bond?? (Someone suggested that on another forum but I could not find any more information on that.)

    Thanks

    1. Rick

      Hi Kelly, the simple solution to your single outlet is adding a 3 way plug into the NG plug or making one from one of the short 1′ length type 3 way plugs, this is very common answer I get from the RV guys out there, here is a link to what I’m talking about ; they just cut of the male plug, add a new male plug with the ground and neutral bonded, this way all 3 of the outlets are then bonded. Hope that helps…

  8. Kelly

    Rick — I found this response in another thread from you yourself! “To make the cord you would need to replace one of the plug ends. Either the male or female side with a new one. And then you would electrically tie together the Neutral (white) with the Ground (green) using a small jumper wire basically. I would also recommend to label that cord and only use for that purpose. Also look into adding a ground rod and connecting the generator to that. The Honda EU’s have a ground lug on the front.”

    I am going to give this a try with a purpose built 12/3 cable that will be used only for the furnace. My plan is to add the jumper on the male end of the cord that plugs into the generator. I will also be using an 8 foot copper grounding rod that will attach to the inverter’s grounding bolt (both of my inverter generators have them), as you suggest.

    Am I correct that this purpose built extension cord with the N-G bond could be used to power basically anything off of the generator (furnace, tv, lights, etc.), but one would not want to use it to either: a) tie the generator to the breaker box via a transfer switch, or b) for any application where you are using the extension cord connected to your home’s “normal” power…. as in either case you would then have two N-G bonds; the one from the extension cord and the one in the breaker box. ??

    1. Rick

      Hi Kelly, Just responded to your previous post, and yes you could you use it for all those purposes, the main safety issue would be if your trying to back feed into your main circuit board so long as you don’t do that and sounds like your going to add the ground rod you will good to go and shouldn’t have any issues.

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