The electrical in my home (old house, newly purchased) is a nightmare. In other posts on here I've mentioned how my zone valve for heating wasn't working because I discovered that the zone valve was connected to both a wire that had come from a step down transformer AND a wire that went straight back to the breaker. When I fixed that, the zone valve worked. There's also all sorts of loose wires that I've found hanging, uncapped. (Fixing everything as I find it)

My latest dilemna is this: There's a downstair workbench/desk that has an outlet over it, pictured:

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Well, that's great, except that outlet is powered by this outlet adapter circled in blue:

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Well if you notice the red circle in the background of that photo, I discovered that is a 'free' bundle of wires that go directly into the breaker box. Its not connected to the breaker box, but it looks like it probably used to power a water heater (based on the label of the breaker in there that's free). Worth repeating that, there is a 30amp breaker with nothing plugged into it I was thinking I'd connect to.

Here's a diagram of roughly what's going on:

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My question is: I'd love to connect that bundle of wires (blue in the diagram) directly to that outlet above the workbench so that its directly connected to the breaker, not splitting off some lightbulb adaptor with a million other things in the same line.

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The cable is huge though (not sure what gauge, pictured below) and so my question is: can I connect it directly to the smaller gauge wires coming out of that outlet? Do you need to do something to connect wires of different gauges?

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  • Is there a white wire in the cable that carries those black and red wires? Can you find any printing on the jacket of that cable for that matter? Jan 16, 2022 at 20:54
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    @ThreePhaseEel There is a white wire yes, it seems to be attached to the box itself in a bar thing. Jan 16, 2022 at 21:01
  • I take it the breaker panel in question is your main panel? Jan 17, 2022 at 0:36
  • @ThreePhaseEel it is. Jan 18, 2022 at 17:00

1 Answer 1


As far as wire size, just connect short 12 AWG wires to the receptacle and use wire nuts to connect them to the existing 10 AWG wires. The connection needs to be inside the receptacle box. Connect the black wire (hot) and white wire (neutral) to the receptacle.

At the breaker panel, you need to replace the 30A double breaker with a 20A single breaker and leave the other space blank (with a filler plate) or put in a single breaker for another circuit.

Connect the black wire to the breaker. Connect the white wire to the neutral bar (based on comments, sounds like it is already connected). Do not connect the red wire.

Note that there are ways to use a double breaker here and get twice as much power by using both black and red wires. That is called an MWBC - Multi-Wire Branch Circuit. But it gets confusing and it complicates installing GFCI, which you most likely need in this location, though receptacle in the ceiling complicates that because GFCI are not supposed to that high up. Really you should install a GFCI/breaker (costs more) or either extend the cable (connection inside a junction box) or rearrange things a bit so that the receptacle is in an easily reachable (without a ladder) location.

  • Depending on where the run is from the old 10g wire junction box, you might consider armored cable to your receptacle. Jan 16, 2022 at 21:27
  • Sounds good and you clearly know your stuff. Would you mind explaining to me (like I'm a 5th grader haha) why the red wouldn't be connected? I just keep thinking to myself (from the VERY little I know about electricity) that you have to have closed circuits in like loops. White is ground correct? Jan 16, 2022 at 21:37
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    240V (water heater) uses 2 hots, black and red, each 120V from neutral (white) and 240V from each other. 120V uses just one hot (black or red) plus neutral. Technically a 240V circuit doesn't need neutral but some (most US clorhes dryers and ovens) also use 120V so they need neutral. Jan 16, 2022 at 22:08
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    To make it extremely obvious, those wires just hanging in the ceiling in the red circle will need to be attached to your new wiring (you can switch to #12 NM-B here) and that connection MUST happen inside an approved junction box. Since your ceiling is exposed, you can use a new work box, nailed to a ceiling joist, feed the existing cable in, then feed your new NM-B in the other side & wire nut them together, then put a cover plate on the new box. It must always remain accessible and cannot be buried behind drywall in some future finishing project.
    – FreeMan
    Jan 17, 2022 at 14:12
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    Just made all your changes yesterday. Outlet works and I didn't burn my house down, thank you! Jan 18, 2022 at 17:00

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