Can you replace a 120 V outlet w/ 240V outlet if there are 4 other 120 V outlets on the existing 120V breaker? Can a 240v breaker also run 120V?

Question

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???

Answer 1

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.

Answer 2

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.