Hi,

I have a wire that seems to have only to conductors in it. It's a gray
wire in which the plastic sheath is tight over the wire. The two wires
are about 1/4" apart. I'm not sure how to better describe it.

It seems to be connected to a double breaker and carrying 240V to the
A/C unit. Does that make sense? I guess if the two wires are 120V
out-of-phase then the AC current can just flow from one of the wires to
the other?

I'm trying to make sense of this for my own education, but also
wondering what kind of wire I would need (12/2?) to replace this one
(it's routed stupidly).

Thanks,

Aaron