Josh wrote:
That's a Code violation. If feasible, you should remove that green wire, and
replace it with black or red.

Pulling the entire green wire through and replacing it with blk or red
isn't feasible. The green and white enter the outlet box and don't
leave. But since there are other outlets in the living room on this
circuit, there has to be a junction box somewhere in the house that
the green wire goes into and branches out of. It's probably in the
attic, and since I have a relatively flat roof, hardly any crawl space
up there and lots of loose fill insulation, I ain't going up there!

I'm going to leave that green wire alone, maybe mark the ends and put
the warning sticker on the breaker box which one of you recommended,
and use black 12 gauge from the wire nut onwards.

I guess the original electrician was color blind. But the wire has
done its job for 51 years and counting without, as Shaun stated,
killing any electricians.

Marking it is good; I'd guess the run was done because was out of
black/red at the time and didn't take the time/trouble to go get
additional wire for one run. It would seem more likely was a DIY'er
rather than licensed electrician but in existing work it doesn't make a
whole lot of sense to pull it only for the insulation color.

If ends are marked and it is used as hot it will be patently clear to
any electrician long before there's an issue. It's not quite like the
situation of white (neutral) in switch leg where there isn't another
black conductor to be used but again since it's existing, "close enuff".

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