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???
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.
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.