How can I get my portable generator to power my house with this setup?

Question

I need help figuring out how to power my house with my 12000/10000w 50amp portable generator. The picture above is my main panel that also houses the meter. I don't have a single main disconnect, but instead have a rule of 6 setup that consists of the A/C, A/C condenser, water heater, oven, dryer, and the sub-panel in the garage that controls everything else in the house. I'd like for the generator to power everything that's on this main panel. I'll probably turn off the water heater and dryer breakers when generator power is turned on.

I was thinking of moving these 6 breakers into a new panel next to the existing panel, then adding a main disconnect breaker and a power inlet breaker in the existing panel with a interlock kit. The power inlet breaker would feed to a 50 amp power inlet box.

Would that work? Or is there a better, cost-effective way to go about this?

Thank you!

Answer 1

There might not be a practical way except to replace this with a modern meter main, either to put the interlock there (if it can work with one) or to use that to feed a new panel.

As you know, you need a way to install an interlock to prevent backfeed. If your garage subpanel has a main breaker or can be fitted with a main breaker or a backfeed breaker that can work with an interlock then you can just put the interlock there. The catch is that then you can't power the A/C, A/C condenser, water heater, oven or dryer from the generator. You can live without the water heater and dryer - and probably without the oven too - during an outage (microwave oven or hot plate can run on a 15A 120V circuit from the subpanel), but I am sure you'll want the A/C. So something is going to have to move, somewhere, somehow. A few options:

• New meter main is the best overall, long-term option. Either the interlock goes there, or you run from lugs on the meter main to a full big new "main" panel with an interlock. Main is in quotes because anything past your meter main is technically a subpanel with neutral and ground separate, but from a functional standpoint it would be the main panel from your house.
• Existing garage subpanel with the A/C breakers moved to it. This will work if either (a) the existing feed breaker and wire can handle the existing load (Load Calculation needed on the garage subpanel's existing loads) plus the A/C (I'm doubtful, but maybe) or (b) larger breaker and wire can be installed to replace the garage subpanel feed breaker and wire. That will depend on what size breakers can be legitimately used in the Rule of 6 panel. It will also depend on the garage subpanel being capable of handling the interlock and generator inlet.
• New garage subpanel with the A/C breakers moved to it. If you put in a large "main" panel (but again, it will actually be a subpanel) then interlock and inlet will be easy. But again, this is dependent on the Rule of 6 being able to handle a large enough feed breaker for the subpanel.
• New subpanel next to the meter main with the A/C breakers and garage subpanel feed moved to it. This has the advantage that you can leave the garage subpanel as is, and you don't have to worry about splicing or replacing the A/C wires as the new panel will be right next to the existing Rule of 6 panel. This should be a standard "main" panel so that you can easily install interlock and inlet. Same issue with feed breaker, but you won't need to replace the wire to the garage subpanel because it is not adding any loads.

So really the key question is whether the largest breaker available for this Rule of 6 panel can handle both the existing garage subpanel and A/C (and optionally oven or other loads as well, but less critical). If that's OK then you have lots of options. If it isn't OK then it is meter main replacement time.

Answer 2

Forget the Rule of Six panel, there’s nothing you can do with it.

Put the generator interlock on the subpanel and just write off water heater, dryer, oven and A/C. It’s an emergency, for Pete's sake, no time to cook Thanksgiving dinner.

Now I know you're not gonna let the A/C go, and my answer is "multiple window units in a limited area of the house". Modern window units are ridiculously efficient - some 6000 BTU units are 450 watts - and so that'll be an easy load for your generator to pick up, unlike the whole-house monster. If you need heat, choose reversing (heat pump) units.

Avoid 1-hose portables, they are too inefficient.

On the Rule of Six panel, there will be no way to put a 200A breaker in that, and the bus is permanently tied to utility. Your best bet will be put a meter-main ahead of it, and let the meter pan in this one be empty. You might be able to use a meter collar there later if you go with a PowerWall or something.