I don't have one of these gasoline powered inverters yet, but am considering getting a portable 2200 watt to power lights, fridge/freezer. We are on a small leg (fewer than 20 houses on it) so we always get triaged last when the power goes out, and we're usually out for three or four days after a big storm.

Is there such a thing as a component that is designed to fit into one of the breaker slots in the main panel, with a three-prong outlet on it, that would accept a heavy duty power cord coming from the inverter?

  • 2
    What you need is a transfer switch. This keeps the generator from back feeding the main. There are some with as few as 4 circuits and many with up to 16. Each switch connects to a breaker and the generator. This is the safest way you choose the circuits to power and how many based on the size of your generator.
    – Ed Beal
    Commented Feb 27, 2016 at 15:35

4 Answers 4


Closest thing to what you ask for that would be legal and safe is a simple interlock. Happens to be my preferred method - it's cheap, and it lets me choose what to power without any sudden need for creative rewiring in the dark.

Depending on what you have for a panel, this may or may not be easy or even possible, or it may be quite easy, cheap and possible. Typically one double-wide (240V) breaker next to the main breaker is designated as the backfeed (generator in) breaker, and then there is a metal interlock device that lets both the main and the backfeed be off at the same time, but which prevents both from being on at the same time. This will be a UL listed device from the maker of the panel.

You are aiming absurdly low on generator size for backfeeding a house panel - a 2200 watt almost certainly does not even have a 220V outlet, for one thing. If that's all you are going to get, use extension cords and don't connect to the house wiring at all.

You have to manage the loads yourself with this system, but any circuit can be connected. If too much power is drawn, a breaker (most likely the one on the generator, or the backfeed) will trip.

The alternate system as per Wolf's answer is to set everything you want to power up on a sub-panel that is the only thing that can be powered in an outage. If you want to power other things, there is a regrettable temptation to do it the wrong way with such a setup (which is one reason I don't like them.) That system is also typical of autostart generators, though of course in that case the generator has to be quite large to enable powering all the loads on the sub-panel at the same time if it's going to autostart, and there's no load management taking place.

Which system is right for you will vary with you.

  • Understood about managing the loads. All I want to do is keep the food from spoiling and have a bit of light. Everything else would be shut off.
    – user41524
    Commented Feb 28, 2016 at 9:23
  • And maybe run the oil burner and thermostat.
    – user41524
    Commented Feb 28, 2016 at 14:01

No, you need to install proper transfer equipment. The transfer equipment allows you to automatically, or manually switch between power sources safely.

If you simply backfeed the panel, you could potentially kill a linesman working to restore the power.


Also, you'll want to segregate which loads matter enough to power via the generator, so you don't bog, trip or fry the generator when a household member carelessly turns on a coffee-maker. And apologies here, I speak in the US idiom not UK, but the obvious thing to me is a "sub-panel" with those key loads, with the sub-panel switched between mains power and genny.

In any case, the switch must absolutely exclude any possibility of the generator back-feeding into the mains. Understand that transformers are 2-way. If your neighborhood's supply transformer is 2400vac, your genny's 230v power can energize the 230v secondary side of that supply transformer, which will put 2400v on the primary side, energizing all connected wires at that voltage.

I notice you did not say "furnace". In the snowy areas of the US, gas furnaces require electricity for thermostats, blowers or circulation pumps, causing them to fail entirely. This is considered "normal" and the California style gas-only furnaces are not even available.

  • Boilers are pretty common in the northeast, though they still need power for various things; then again, wood heat backup is also pretty common.
    – Ecnerwal
    Commented Feb 27, 2016 at 18:38

The simplest approach sacrifices the automatic switchover, but can be done at no cost. When there is a power outage, just plug your fridge, computer, standing lamps and the like into the generator. BTW, 2,200 watts may or may not be enough to run everything you want to power.

  • I wanted to avoid running long extension cords.
    – user41524
    Commented Feb 28, 2016 at 9:31
  • Yes, long extensions are a bit of a bother. Yet, extension cords are tens of dollars, transfer switches are hundreds of dollars, plus installation (e.g. amazon.com/s/ref=nb_sb_ss_c_0_18/…). Note, 2,000 watts may not be enough, even if you time share you heavy loads. You might start off with extension cords and then switch to a transfer switch when you are sure you know what you want to power from the generator.
    – Yehuda_NYC
    Commented Feb 29, 2016 at 14:47

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