I thought it was 10 gauge for a 30amp dryer outlet (NEMA 14-30).
And surely they used properly grounded 4 wire.
Unless it’s a heat pump unit, in which case I don’t know anything (some are 120?).
Or it’s in a civilized country with 240V, in which case I know nothing at all.
I sincerely appreciate this. You have further proven that I don’t know anything at all about other countries.
And an additional thanks for the thorough explanation in the linked comment. As a layperson, I knew different options existed, but I didn’t know what they were, or why.