Neutral Bonding Parallel Generators

It’s really pretty easy, and you only need one bonding plug…

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 H

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).

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 $15 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…. Mike