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.
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I have a Honda 2200I generator and found a deal on a 2300 Yamaha. Can I run a parallel between these two?
No that won’t work. They have to be an exact match to work properly.
Yes it will work. I have connected my Honda EU2200i with a firman 2000i with the firmans supplied parallel cable. I just took a wire and attached it to both grounding screws on each generator and it is now running my AC. I had the Honda gen and it ran everything in the trailer except for the AC. I didnt want to spend another 1k on a honda so I got the firman at costco for 450. The parallel cable was included with the generator and it fits the hondas parallel input perfectly. So if I can run a firman i know it would be no problem for a yamaha.
Hi Mike,
I have two bluetooth Ryobi 2300 Generators.
I’m in Canada and neither Ryobi or the retailer are currently providing a Ryobi parallel kit.( contrary to websites here .ca it Ryobi customer service) I am not complaining. What I see is that a Firman 1005 and/or 1205 parallel kits have the same 2 non directional banana plugs as the Ryobi. I tried hooking them together with a 1005 and it didn’t deliver output through the kit. Is there a method I should be using?
Wade
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
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?
That’s probably correct, depending on how your generator transfer switch is wired. On some of them they depend on the on-board generator itself to provide the G/N bond, while others create the bond within the generator switch wiring. How to know for sure? Well, just connect up your generator to the extra 30-amp input you wired in, and plug a 3-light outlet tester into any of your RV’s outlets. If it registers the proper 2-amber/0-red light combination, then your portable generator is being G/N bonded by the transfer switch. Here’s a video on how that works: https://www.youtube.com/watch?v=M-bTLdMjuqU
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.
Karen- there’s a couple of questions here. First, it’s the amperage output of any generator that will be the deciding factor whether or not you need a second (companion) gen. Second, it’ IS possible to run a single a/c unit that typically draws 15 amps or less from a single 20 amp output generator using its 15 amp plug and your 30 to 15 a. adapter for your rv. Hope this answers your concerns.
Remember, it’s also about the inrush current needed to start the compressor motor, which can easily be 2 or 3 times the normal running current. That’s what trips the overload protection on most generators, and reducing that inrush current to a more reasonable level is what the Micro Air Soft Start does by modulating the current feeding the capacitor start winding.
Karin, you are correct. The only thing that the Companion generator does differently from the feeder generator is supply a 30-amp/twist-lock outlet and circuit breaker. So you can indeed use a single, standard (non companion) generator with an appropriate 30-amp dogbone adapter to power your RV. And yes, in either case you’ll be limited to around 18 amps of current or so. However, the Micro-Air Easy Start is pretty genius at controlling the air conditioner’s compressor start-up current, which is what allows you to get by with a single 2,000 watt generator and still run an air conditioner. as long as you’re careful with other power usage at the same time.
So what ill effects happen by not using a bonding plug for your above application?
Generally, you don’t need any kind of ground/neutral bond when running from a portable generator (or two). However, if your RV has a built-in EMS/Surge-Protector (or even a portable one you want to use) it will shut down the power because it will interpret the isolated/floating neutral as a open-ground connection. Also, some modern RV (and home) furnaces and refrigerators won’t operate at all with an open-ground condition. In addition, GFCI’s won’t operate properly without a bonded neutral/ground (although that’s not really a safety issue). And trying to troubleshoot an RV electrical system while running on a floating neutral generator can be a real challenge since the hot-to-ground voltage can fluctuate between 0 and 120 volts, typically floating around 60 volts AC or so. Note that ALL built-in RV generators that use a transfer switch create a neutral/ground bond while running on generator power, and the transfer switch floats the neutral while on shore power since utility power creates a ground/neutral bond back at the service panel. Since you typically don’t have a generator transfer switch in circuit when powering your RV from a portable generator, things can get a little weird sometimes.
Thanks for the reply , sorta makes some sense. I’m more in the thinking that nothing in this operation is actually grounded. Been using mine without for many years now and I do understand if hooked to my house that I do in fact have a ground but not with the trailer. Thanks again for the explanation
It’s confusing because the word “ground” is used for all sorts of electrical things, some of which aren’t connected to an “earth” ground at all. Bonding the Neutral and EGC (Equipment Grounding Conductor) together is something else altogether.
You may trip the gfci using certain appliances.
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.
Bill, I agree, but we also have to consider the weight. My Honda E2000i is about 48 lbs, where a 3500 is closer to 100 lbs. I can manage 48 lbs, but it’s really difficult to lift 100 lbs about 4 feet up into my truck bed. I would like to have a 3500, but for me, it ain’t gonna work when I’m only 60 lbs more.
Wayne, you are correct. I can easily pick up one of my Honda EU2200i generators (at 47 lbs), and if all I’m doing is charging batteries then one generator is all I need. However, my Honda EU3000i generator is 131 lbs, which is WAY too much for me to lift by myself into the back of a pickup truck. Yes, I would do lifting like that without hurting my back in my youth, but those days are gone. And my EU7000is generator weights 262 lbs dry (no gas), so even if I have help we put up a ramp to load it into a pickup.
Bill, that’s a question I ask myself often. For most, the convenience and cost of a single is the answer. Most of the time boondockers only need up to 20amps or so primarily. There’s one appliance these won’t power up- an a/c unit (or 2). In those cases some carry the extra generator. Winter and Spring in the southern deserts is usually mild so using the a/c isn’t necessary.
Thanks Drew.