RVelectricity: DIY Generator Neutral Ground Plug


Dear readers,
In response to several inquiries on how to make your own neutral/ground generator bonding socket, here is the complete DIY generator bonding socket article that I wrote almost 10 years ago.

When a Portable Generator Won’t Power Your RV

See my video on testing a floating neutral here.

I received this email from a reader who wants to power his motorhome from a Honda portable generator.

I have a 2011 Fleetwood 40ft. Trying to get my Honda EU3000 generator to power the RV for a few items. My screen after plugging in will show NO CHARGE. This generator will power anything else I try, like a 30 foot trailer with an air conditioner, compressor, etc. I also have a Coleman 5000 and that will power the RV.

I have a 50 amp female adapter cord going to 30 amp (3 prong) male. The Honda worked with my 2002 Monaco snag the same way. The reason I like using the Honda is because when I’m on the track at this time of year there’s no need to run the RV generator because there’s no need for air conditioner. I called Honda and they did not help me. —John Z., Purcellville, Virginia

Basic Ground Neutral Bond Theory

John, all RV electrical systems are wired with their floating ground and neutral buses (not tied to each other). There are many good reasons for this, specifically that it is a requirement of the NEC and RVIA codes that the safety ground wire never carry load current. Additionally, there can be only one ground-to-neutral bonding point in any distributed electrical system in the United States.

Now when you plug your RV into power at a building (your garage outlet) or campground (pedestal outlet), your RV has its ground and neutral buses “bonded” (connected) together outside as part of the service panel safety ground. ground system. Again, there are many reasons for this, but the fact is that you can only have one GN tie point according to the National Electrical Code and RVIA building codes.

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When a floating neutral generator does not work…

So when your RV is powered by its onboard generator, that GN link connection is created by the transfer switch set to generator mode. But when the transfer switch is set to receive shore power, your RV expects the external power source to connect its ground and neutral wires together.

Now, if you have an inline voltage monitoring system from a manufacturer such as Surge Guard or Progressive Industries, your voltage monitor checks that the neutral and ground voltages are very close to each other, probably at less than about 3 volts.

This works well if you’re plugged into a properly grounded and bonded shore outlet, but this voltage protector can be tripped by plugging your RV’s power outlet into a portable generator without an internal neutral-to-ground bond. If you don’t have a voltage protection device on your RV, you may never know your generator has a floating neutral (unbonded GN bus).

Generator Types

Contractor-type generators like your Coleman 5000 are usually NG-bound internally, which is why they run your RV very well. However, many portable inverter generators from companies such as Yamaha and Honda (your EU3000, in particular) have floating neutrals (no internal neutral-to-ground bond) because they expect an external NG bond to occur elsewhere . And while RV-approved generators may have an internal NG link, it appears that many of Honda’s and Yamaha’s most popular portable inverter generators have floating neutrals.

Honda Support could not help

I discussed this with Honda engineering, and they confirmed that their inverter generators have floating neutrals and they just say you must follow all local electrical codes for grounding. So your EU3000 doesn’t provide the neutral ground bond your RV needs to think it’s getting properly grounded power, while your Coleman 5000 already has a neutral ground bond to make your RV work properly. VR. It sounds crazy, but that seems to be the script.

DIY your own…

It is quite simple to wire a special “Neutral-Ground” jumper plug for your Honda or Yamaha generator that will allow you to power your RV through its voltage protection device. You can get or make a 15 amp dummy “Edison” plug with the neutral (white) and ground (green) screws connected by a piece of 12 or 14 gauge wire (see photo below).

This GN jumper plug can be plugged into one of the generator’s unused 15 or 20 amp outlets, and the entire generator electrical system will be tied to the NG. You can then use the other 20 amp Edison outlet or the 30 amp outlet to power the RV.

Just be sure to mark this outlet specifically for its intended use. It won’t really hurt if it’s plugged into a properly wired household outlet. But this will create a secondary GN binding point which could induce ground loop currents and create hum or hum in an audio system. This will also ensure that any GFCI receptacle in the branch circuit will trip even with a few mA of load current.

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Buy a factory-made one

If you’re not 100% comfortable wiring your own NG link jack, you can buy one from Southwire on Amazon for less than $17 delivered. I keep one in my carry bag when I need to power PA systems from a Honda generator, and it works great for that application as well. But if you don’t have any sort of EMS/Advanced surge protector, or aren’t powering sensitive electronics, you probably don’t need an NG link socket at all. But when you need it, you really need that. Buy one on Amazon HERE.

Note that this is a generator only GN link socket that should only be plugged into a portable generator when powering your RV. It should never be used to create a counterfeit ground in a residential or RV outlet that has not been properly wired with a grounding conductor.

Let’s play it safe there….

Send your questions to me on my new RVelectricity forum here.

Mike Sokol is an electric sound expert and professional with over 50 years in the industry. His excellent book RV Electrical Safety is available on Amazon.com. For more information on Mike’s qualifications as an electrical expert, Click here.

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