On 12/7/2010 10:05 AM, Nova wrote:
Morgans wrote:


"Bill" wrote in message
...

Scott Lurndal wrote:

writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).


I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

scott


Because???


You do not want to have the possibility that one circuit has faulted
and the other still is hot in the same enclosure. You could still have
a hot circuit in there, when you think that it does not have juice to
it. By connecting both together, if one trips, you are assured that
they both have been shut off, and limit the possibility of getting a
hold of a hot wire or hot energized light switch or light.

The wiring arrangment using 12/3 for two feeds is called an "Edison
Circuit". Because the two circuits share a common neutral there is a
good chance that when one breaker trips the outlet/device affected can
still have a live neutral, being back fed through a device plugged into
the non-tripped circuit. This is the reason the two breakers should trip
together. I know my local code requires it and I think it's specified by
the NEC.

See:

http://www.phy.ornl.gov/divops/ESH/98-2.html


Thanks for the link. It leads one to think (and that's usually good!).

Bill