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I have a panel in my garage with a "Generator" 30A breaker. I know I shouldn't be backfeeding the generator (I inherited this setup and am scheduling an electrician to put in a transfer switch). Having said that, can I turn that 30A breaker on and use the 220v outlet that it goes to?

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    Is that breaker interlocked to the main so it can't be on when the main's on? What make and model of panel is this by the way? – ThreePhaseEel Feb 13 '18 at 2:35
  • Don't put in one of those hokey Chinese transfer switches with like 6 switches, 1 for each circuit. It is wiring spaghetti and a general disaster. Better to use a subpanel of your chosen size, with the top 4 spaces occupied by backfed breakers with an onboard interlock (panel $60-150, breakers $10 each, interlock $30, Siemens makes a fine one). Then you move any mix of 120/240 circuits to the subpanel. – Harper - Reinstate Monica Feb 13 '18 at 3:15
  • I much prefer the setup illustrated below - I have a generator input interlocked with the main of my 200A panel, and I can run any device on the panel without "getting creative" so long as I don't overload the generator (and it will tell me if I do.) Limited subpanels or transfer switches encourage unsafe "creativity" when some item not on them is deemed important during an outage. The only reason to have a transfer switch is if you need "autostart/autotransfer" and most of us really don't. – Ecnerwal Feb 13 '18 at 3:20
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That should be physically impossible, and the "outlet" should not be an outlet (it should be a boxed plug).

If it's physically possible and the outlet is an outlet, it's not a generator input unless you enjoy having your service terminated when the power company finds out about it. So remove any "generator" label, take apart the suicide cord, and use the outlet as an outlet.

It's quite possible to backfeed in a safe and correct manner with a listed manual interlock (the main OR the generator can be on, both can be off, but both cannot be on, by physical interlock preventing that) and a boxed-plug input to the backfeed breaker. You absolutely do not need a (generally overpriced) transfer switch.

This is a manual interlock for a Square-D QO panel - there are other styles for other panel types/brands.

Manual interlock

Here's a typical correct generator input, fed from an extension cord with a receptacle on the end that won't (easily) electrocute you.

generator input plug

  • This is the ideal way to do a transfer switch. Also note this is a reputable maker of service equipment: Square D. Eaton, Siemens, GE being others. – Harper - Reinstate Monica Feb 13 '18 at 3:29
  • Thank you! I'll look into the manual interlock and... yes... not use the suicide cord. This must have been a DIY job that the previous owner did, I can't imagine any electrician setting this up for someone. – darrickc Feb 13 '18 at 14:36
  • @darrickc it's possible no electrician set it up at all. A NEMA 10-30 or 14-30 receptacle could meet your description, and that might already have been present for a dryer. – Harper - Reinstate Monica Feb 13 '18 at 20:50

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