It's an electric dryer that requires a 220V socket; there's no other
sockets in the house that'll do.

I tested the circuit breaker today and it looks like all the breakers
are supply power. I had no voltage across the bare wires of the main
outlet. I had taken it out of the wall and tried measure across its
wires to no affect. This is very strange to me. My circuit breaker
box doesn't have any tied breakers, and I only have 20A breakers in
there. When I got the house back in July, the inspector alerted me
that I should change that so that I don't have only half the circuit
break on me. We never determined which circuit breakers were actually
handling the dryer, and I'm starting to think none of them are doing
that. The house was built in the late 70's, and I doubt its had a
second panel installed someplace. I'm a little confused.

I will test the breakers again tonight, but I might need an electrician
find the path of that circuit for me. The dryer outlet and breaker box
are both in the garage, along with my gas heaters. Is there any place
else I should be looking to find the source of this circuit?