RVelectricity: Parallel generator neutral bonding

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By Mike Sokol

Hello Mr. Sokol,
When pairing two inverter generators do you use a neutral/ground bonding plug on each generator or will one suffice? Thanks. —Dave Hoffmann 

Dear Dave,
Hey Dave, you can call me Mike (but I do make my long-suffering editor, Diane, call me Professor Sokol). (No he doesn’t, but I should. 😀 —Diane)

That’s a pretty easy question to answer once you understand the basic theory of parallel generator hookup. I’ve drawn up this simple diagram which should make the connections very clear. It’s really as easy as 1, 2, 3…. (and maybe 4). Remember, to see any of my graphics full size you just need to click on them.

For this exercise I’m going to assume you’ve got a pair of Honda EU2000i or EU2200i generators, one with the standard 20-amp duplex outlets (which I’ll call the feeder generator) and the other one being the Companion generator with both a single 20-amp outlet and a 30-amp twist-lock outlet.

Note that the EU2200i Companion generator can’t fully power the 30-amp outlet by itself unless you also have a Feeder generator connected with the parallel kit. But even in solo mode the standalone Companion generator’s 30-amp outlet will still work, albeit with limited current (18 amperes or so) and wattage (2,000 or so watts). That’s why it takes Two to Tango (as it were).

#1) Connect the matching generators together with the appropriate parallel cable kit, including the extra ground wire connection which bonds (connects) the two generator frames together. You will want to get the official parallel kit for your particular generator since they must have a heavy-duty banana plug on each end with the terminal cover to protect you from contact shock if one of the plugs pulls out of the generator. So don’t be tempted to build this yourself. Get one made for your exact generators.

#2) Install a generator 15-amp bonding plug on the Companion generator’s 15/20-amp outlet. You can buy a Southwire brand G/N bonding plug from a variety of vendors for around $10 or so. But this is simple enough to build yourself if you’re handy. I’ve detailed the DIY construction of this G/N bonding plug in dozens of published articles. And yes, I’m the guy who invented this thing.

#3) Connect an appropriate twist-lock Generator to RV TT-30 or RV-50 dogbone adapter into your Companion generator’s 30-amp outlet. If your brand of “Companion” generator already has a TT-30 RV outlet, you can simply plug your RV’s 30-amp shore power cord into it directly, or use a TT-30 to RV-50-amp dogbone adapter to connect the parallel generator set to your 50-amp RV.

Note that there are two versions of a 30-amp generator twist-lock adapter: one with 3 prongs and one with 4 prongs. The 3-prong version is for the 120-volt/30-amp outlet you’ll find on most 2,000-watt “Companion” generators. The 4-prong version is for the 120/240-volt/30-amp outlet you’ll find on most 7,000-watt inverter generators. For this hookup you need the 3-prong/120-volt version.

#4) There is no need to connect either generator to a grounding rod in the earth unless you’re distributing power to multiple RVs, then it’s a code requirement. Remember, grounding and bonding are two different (but related) things, and the frame of your generator(s) will be properly bonded to your RV chassis via the green/ground wire in your shore power cord, and the generators will be bonded together via the “ground” wire of your parallel kit. So it’s all good if you connect it as illustrated.

See … it’s really easy. Hope this helps.

Let’s play safe out there….

 

 

(aka Professor Sokol) [←Diane did that]

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

For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign.

##RVT923

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Charlie Flood

Hey Mike , I have 2 ryobi 2300 inverter gens that I would like to run together with a Wen parallel kit, the connections are not marked on gen as to red positive or negative . Which plug is positive or does it matter if you use same set up on both units? I have a Hughes auto transformer50. Amp and a 50 amp ems from progressive Ind. will the bonding plug work with this setup? We dry camp where they will not let us run on board gen because of noise.
Thanks
Charlie

Rich Witt

Mike,
My 5th Wheel came wired for a Generator, but did not come equipped with a Generator. It has a transfer switch with one side wired to the shore power and the other to the Generator connection. I’ve wired in a proper 30 amp inlet to the Generator connection wires to connect my Honda Companion 2200. If I understand this correctly, since I’m feeding through the transfer switch on the Generator side of the switch, I do not need to have a bonding plug on the Companion, but if I were using the shore power side then I’d need to use the bonding plug. Is this correct?

Karin S.

Mike, I have a question….You state the Companion genny can not fully power the 30amp outlet without the feeder genny. If it would work, (it having the correct plugin) is that not true of the feeder genny? I mean if you only wanted to use one genny, it too could not fully power the 30amp outlet? I purchased a MicroAir for my RV airconditioner, in hopes to just use the Companion genny (since it has the proper plugin). I know if I’m operating the air conditioner, then I won’t have many amps leftover, but if I’m dry camping, which is want I am wanting to do more of, than I will just do a little less.

Am I looking at this correctly? I have a friend who mostly dry camps and uses only the companion genny and gets along fine. Of course he isn’t operating all things electric inside his RV. He does have one up on me with some solar, but I too will be purchasing a 140watt portable solar kit from Zamp.

As always, thank you for your expert assistance. I read and re read all your posts to keep myself educated.

Jeff Arthur

So what ill effects happen by not using a bonding plug for your above application?

Bill T.

Hi Mike. My question is ‘Why would anyone need to run parallel generators”? If their electrical needs are that much for an RV why wouldn’t you have one generator that meets the capacity of your needs?
Regards.