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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.

6 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.

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