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I have a sub panel with three 240v/120v breakers. One is dedicated to a microwave no longer present. The line to the outlet is 12/3. How to convert the situation so the load going to the outlet is 120v? All three breakers are Square D QO 2-pole. Can I just cut the red wire at the breaker and outlet?

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    Your question is not clear, if you have 3 double pole breakers and you only want to have 120v at the ampacity marked on the breaker just use 1 lug on that breaker connecting the black to that lug. The white and ground go to their respective busses (built after 99 the ground and neutral buss on the sub should be separated with the neutral isolated from ground. The wire size should be #14 or #12 for 15 amp and 20 amp breakers this is the max size allowed on a standard receptacle. If a single dedicated receptacle on a 20 amp circuit (#12 wire) the receptacle must be20 amp if a duplex it can be 15
    – Ed Beal
    Commented Feb 6, 2022 at 20:58
  • @geometric I just approved an Edit from another brand-new user. Edit doesn't make sense unless actually an alternate. So, "Joe Adams" if you are also "Geometric", put a comment here and flag for a Moderator to merge the two accounts. And if you are not really one person then please read through to see if the changes are OK.
    – manassehkatz-Moving 2 Codidact
    Commented Feb 6, 2022 at 21:27
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    A picture of the panel would help.
    – manassehkatz-Moving 2 Codidact
    Commented Feb 6, 2022 at 21:27
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    The question sounds like you had a 240V microwave. Did you? As noted, it's unclear.
    – jay613
    Commented Feb 7, 2022 at 0:43
  • My best guess is this is actually a multiwire branch circuit, so each of the 2 outlets is on a different phase. In that case, each outlet is still 120v. A 240v outlet would (or at least very much should) use a different shape.
    – Grant
    Commented Feb 7, 2022 at 2:55

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Don't ever cut a wire!

Cutting a wire off is illegal because there's no way to render that wire safe. It can't be insulated properly, so the whole cable would have to be scrapped.

It's also rather shortsighted, since your needs might change some day.

The correct thing to do with an unneeded wire is terminate it in an appropriate insulator (small wire nut appropriate for 1 wire, Wago lever-nut, push-splice, whatever). Do the same at both ends.

If you had a 120/240V circuit, and you want a 120V circuit, you can grab either hot wire, neutral and ground and there you have it. Cap off the other hot wire at both ends.

Just keep using the 240V breaker

If the 240V breaker is already 15A or 20A, you can go ahead and use "half of the 240V breaker" as a 120V breaker. That's perfectly fine - really.

Since you are simply downgrading this circuit and not installing a new circuit, the new AFCI requirements should not kick in.

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