I installed a dedicated 240 V outlet next to my breaker box outside to power my new A/C. I am currently running an extension cord. I would like to replace an existing 120 V outlet inside the house with a 240 V outlet so I can do away with the extension cord. My issue is that the existing 120 V outlet I wish to replace is wired to 4 other 120 V outlets in my living room all off the same single pull breaker. Those outlets have a black hot wire, a white neutral wire and then a grounding wire but there is an additional red wire. I’m assuming the red is what runs to each of the other 120V outlets in the room. Can I replace the breaker with a double pull 240 & install the 240 V outlet and run the red wire off that outlet to the other 120 V outlets? Is this safe? Or will the other outlets overload???

  • Where does the red wire go inside the circuit breaker panel? Are any of the outlets controlled by a switch? Also it's single pole. Sep 4, 2022 at 19:04
  • @Harper-ReinstateMonica I'm not sure the red wire in question actually goes to the panel, the OP would have to confirm that, if so it could actually be a MWBC, Still this whole thing is a bad idea. There are truly horrible hacks that could make this work, but I refuse to even mention them. Sep 4, 2022 at 19:22
  • So the best idea would be to run a new line with a dedicated breaker for the 240 V outlet.
    – Kyle
    Sep 5, 2022 at 1:39
  • @Kyle it depends on the nameplate of the 240V device, and what the story is with the red wire. A 120/240V MWBC is legal. Sep 5, 2022 at 20:54

2 Answers 2


There are a number of different issues here. But the bottom line is that due to:

  • Unlikely you have a true MWBC that would allow a shared 240V/120V setup
  • A/C likely needing a dedicated circuit due to power requirements. If it uses more than 10A then you can't share a standard 20A circuit with ordinary receptacles. Or at least, you can't if it is hard-wired and shouldn't if it is plug-in.

this does not sound like a good idea. Far better would be to run a new 240V circuit for the AC. The good news is that you don't have the very common problem of "no room for another breaker" because you already have the breaker/dedicated circuit for the AC. Just a matter of running the correct wire (14 AWG for 15A, 12 AWG for 20A, 10 AWG for 25A or 30A) and installing the correct type of receptacle.

  • 1
    Thank you! I think this sounds like the best and safest idea! I appreciate your comment!!
    – Kyle
    Sep 5, 2022 at 1:42

Do you have switched outlets? The red wire for outlets is often used for switched outlets. Switched outlets are where you can plug a lamp into one of the sockets of a duplex receptacle and use a wall switch to turn it on and off. The other socket is always hot.

Bottom line to answer your question: Very unlikely your plan will work unless you have an actual MWBC, which would be very uncommon for a living room.

Like Manasseshkatrz.... said you should install a dedicated circuit for your A/C. I see no way to re-purpose convenience circuits from 120v to 240v with multiple outlets on the circuit.

  • Thank you so much! I will have to run a new line! I appreciate your help and input!
    – Kyle
    Sep 5, 2022 at 1:41

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