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Trying to determine if 2 each DuroMax XP12000EH 12000 Watt generators can connect through a single "A510C Pro/Tran2 50-Amp 10-Circuit 2 Manual Transfer Switch". My home total current is 16,750 watts with stove and water heater and a spa is operating including ceiling fans, lights, Televisions, Internet equipment etc...I understand the issue of synchronization but that is not necessary with two gen's running on separate circuits as long as the grounds are separated and no feed back can occure, I am making this assumption based on theory not a fact I have ever done.

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    Unless living off grid, you can probably turn off the spa(except for medical reasons) and the water heater(will keep hot for hours). Unless making a turkey dinner, the stove probably will not need full power either. Generators should only be for essential power. 50 amp switch can only handle one of those generators at a time at max power.
    – crip659
    Aug 13, 2023 at 20:58
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    No. But rethink this. You don't need to provide full power to everything when the utility power is out, unless you are living off-grid. (But if that were the case, you wouldn't be talking about a transfer switch.) 12,000 W is actually a lot of power. Most likely if you skip the spa and water heater and stove you will use a lot less. And very likely if you manage things carefully you can get any one of those 3 running at a time while still powering lights, fans, TV, internet, etc. Aug 13, 2023 at 20:59
  • And if you put in a generator interlock on your main panel then you will have the option to power any devices you want during an outage - as long as you stay within the generator capacity. As opposed to a 10-circuit transfer switch which limits you to 10 pre-selected circuits. Aug 13, 2023 at 20:59
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    Why do you want to run everything in your house when the power's out? Aug 14, 2023 at 0:11

3 Answers 3

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  1. Most generators cannot be connected in parallel because of synchronization issues, as you mention.
  2. Connecting them to separate circuits would work, unless the circuits are effectively in series. In North America, most domestic electric service is 120 VAC split phase. That means that some appliances, such as stoves and dryers, use three wires: 120 VAC φ1, neutral and l20 VAC φ2 180° out of phase with φ1, so there is 240 VAC between φ1 and φ2. A 240 VAC appliance would place the two generators in series. Since the generators are not synchronized, there would not be 240 VAC across the two, and one generator could try to drive the other... a bad situation.

So, you might use two generators, but only if the circuits are completely separate, not connected to a 240 VAC appliance.

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Not going to work. Don't waste your money on the transfer switch - they're costly and not very good, and actually create hazard in some situations.

It is impossible to make 2 generators feed equipment powered out of the same load center / panel. It is not going to happen.

Since you're willing to install extra equipment and do a bunch of wiring, go ahead and install two subpanels. In each subpanel, install a sliding plate interlock - the easiest way is to use Siemens 12-space or larger panels and the Siemens ECSBPK01 interlock.

Now permanently move any circuits you want on generator to one of the two subpanels, spreading them out by their power requirements. I recommend putting all your most critical loads into one panel and all the "second tier, would be nice" in the other.

Each panel gets fed by a different generator.

The kit I just listed is far cheaper than the transfer switch, and will work and be code legal.

I recommend adding some EMT conduit between the old panel and the new subpanels, so you can leave the Romex cables going into the original panel they are wired into, and simply extend the hot and neutral using THHN wires into the new panel.

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Not meaning to be mean, but the comments contribute to a total hack job unless you have 2 200 amp panels one for each generator. Still, you'd have 2 generators to start and connect and maintain.

I'd step it up a notch and, as they said in the movie Jaws, "we're gonna need a bigger boat". By that I mean, just get one larger generator that can supply your needs. I just installed at 15KW Kohler generator (propane powered) at my son's new house and it's awesome.

Connect it to the main panel with the appropriate plate lockout between the gen breaker and the main breaker. If you wanted to step it up another notch, get the Kohler 200 amp auto xfer switch...it automatically starts the generator and transfers power during outages from utility to generator. If you go that route, there may need to be some re-wiring in the main panel to isolate the neutrals from the grounds for it to be code legal since it's now technically a sub-panel.. I'd like to make a product recommendation, but that's OT here, still they are easy to find with a search.

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