In article , "toller" wrote:

"Charles Bishop" wrote in message
...
In article , "toller"
wrote:

It is called a multiwire circuit.
It saves a little wire and can be a bit more efficient on big loads. The
breakers are tied together because they share a neutral, and it is best
that
you turn both off it you turn either off. Also, tying them together
prevents you from putting both on the same leg; which is what someone did
to
one of mine. (Like 240v circuits, a multiwire uses opposite legs.)

Given that the house is wired with romex (12-2) is there a benefit to
doing it like this? I can see where there might be using 12-3, but if it's
just black/white/ground it seems like the same amount of wire needs to be
run. Maybe 12-3 comes into one of the j-boxes and they use 12-2 from
there?

Sorry, I "assumed" it was 12/3. The only reason to run two completely
separate circuits to a 240v breaker is that you have half of a outlet on
each circuit; then it is nice that they go off together.
But since you don't have that, I can only think the electrician was using
what he happened to have with him.

Perhaps, but the two breakers can be decoupled (separated electrically)
easily by taking off the plastic connector that ties them together.

Does my suggestion that it's 12/3 from the breaker box to a j-box, then
from there using 12/2 make any sense? It seems like a lot of trouble to
save a little on wiring. I can look into the breaker box next time. The
house is oldish, but was remodeled within the last 20 years I'd think.

charles