Adding 120V Receptacle to One Leg of 240V Circuit

[Mighty Mouse]

I would like to add an outdoor 120V receptacle on one side of my house without having to make a penetration through the foam-insulated exterior wall. There’s a ductless mini-split outdoor unit close to where I want the new receptacle, so I’m thinking I could tap into the mini-split circuit to add my new receptacle. The mini-split is on a 20A 240V circuit and has a disconnect near the outdoor unit. Any reason I can’t tap into one hot leg of the mini-split circuit at the disconnect to add my new 120V receptacle? If I use 12 gauge wire, the existing 20A 240V mini-split breaker should protect the new receptacle and feed wire, correct?

 

[SonnyDay]

Code issues aside... You'll need a neutral for that 120v receptacle. So unless you have an unused one on that 240v circuit (sometimes guys run 12-3 w/ ground and just cap the unused 3rd wire), you'll need to run wire back to the panel. At that point, you might as well run a fresh 12-2 120v home run...

 

[MTN Humper]

I would not do that. Minisplit control boards, inverters, etc. are very susceptible to damage from voltage drops and imbalances. Depending on what you are planning to energize with that outlet, like anything with a motor, the inrush current of the motor starting could really cause issues with your minisplit.

 

[Marble]

There are a couple of solutions, run a new 12-2, or put in a tiny step-down transformer.

But harmonics may cause issueus within the mini split or voltage irregularity.

I sell step down transformers every day, but i am not an electrician...

Sent from my SM-S918U using Tapatalk

 

[Mighty Mouse]

Code issues aside... You'll need a neutral for that 120v receptacle. So unless you have an unused one on that 240v circuit (sometimes guys run 12-3 w/ ground and just cap the unused 3rd wire), you'll need to run wire back to the panel. At that point, you might as well run a fresh 12-2 120v home run...

Appreciate you sharing your thoughts. I haven’t opened up the disconnect box yet to see exactly what I have to work with. To your point, if there’s no neutral wire, my idea is DOA.

I figured NEC probably doesn’t allow what I’m proposing. There’s no code enforcement where I live out in the sticks, but I do generally follow NEC as a best practice (I might make an exception in this case).

 

[HuntHarder]

Not the end of the world, what you are proposing. As you mentioned, no Neutral, you are DOA. If it has it, your idea, while against code, would work with no safety issues. Only issue could be potentially tripping the breaker with an overload current issue, depending on what you run from the outlet. The wire is protected with the proper size breaker.

 

[Mighty Mouse]

I would not do that. Minisplit control boards, inverters, etc. are very susceptible to damage from voltage drops and imbalances. Depending on what you are planning to energize with that outlet, like anything with a motor, the inrush current of the motor starting could really cause issues with your minisplit.

Good to know about mini-splits being sensitive. Most of the time, the new receptacle would only be used for a 12V trickle charger. Occasionally I would plug an electric hoist into it to lift up deer for skinning and quartering. And I could see myself plugging in an air compressor every now and then.

If I tapped in upstream of the disconnect, I suppose I could kill power to the mini-split anytime I’m going to put a significant load on the new receptacle. I doubt I would remember to do that every time though.