On Wed, 23 Dec 2009 13:56:58 -0800 (PST), Mikepier
wrote:

First, make sure you do not have 20A breakers on 14 guage wire. If you
do, change them to 15A breakers now. Thats what could be causing your
conduit to get hot.
Second, you should only have a double pole breaker for 220V circuits.
Although technically it will still work for seperate 110V circuits,
it's not proper practice.
Also you might have an Edison circuit, that is 2 circuits sharing 1
neutral, so its possible that even though you shut off 1 or 2 breakers
to a circuit, the neutral is still being used for your live circuit.

If that is the case in North America something is DEFINITELY waired
wrong. With a ganged breaker, the neutral, if shared by two circuits,
would be share ONLY by the two circuits on the shared breaker.

And the double pole brakers can (and should) be used with split
receptacles, but NEVER with different circuits physically in different
parts of the house.
So the space heater you were using upstairs could be using the same
neutral for the circuits that you shut off. You need find out how your
lines were run, particularly in that junction box.

And it it IS, get it rewired properly YESTERDAY if not sooner.