On Fri, 03 Dec 2004 16:56:53 GMT, "John Moorhead"
wrote:
Folks -
I'm back... Now it's a wiring question. I'd like to run a string of outlets
at benchtop height, and run two circuits. I'll put a pair of outlets in
each box, 1 on each circuit. Can I safely run 12/3 for a pair of 20 amp
circuits using a common neutral (white) and ground? I'd run the red wire
(marked black) to one outlet and the black to the other. The two outlets
would share the white wire, along with the grounds.
At the panel, I'd have the red (marked black) wire going to one CB and the
black one to a separate CB. If I can do this, I'd have to string way less
NM... Would this be a violation of code? Is this safe?
So far the answers you've gotten are either wrong or way wrong.
Shared neutral is certainly legal in the U.S. For those pontificating
on how it's allegedly unsafe, the two hots MUST be fed from a duplex
breaker, which does two things: it ensures that both feeds are on
opposite buses which means that the neutral currents for each branch
are 180° out of phase and thus subtractive, and it ensures that when
the breaker is tripped (intentionally or otherwise) there are no hot
leads in a box with two separate branches in it.
So the short answer is, yes, you can do that.
The long answer is I don't like shared neutral circuits and avoid them
like the plague. Call it personal prejudice but you have to make sure
you have a continuous neutral (all pigtails to the receptacles) so
that you don't wind up with 240V across the devices if the neutral is
lost.
Wire is relatively cheap. No matter how big your shop (well, up to a
reasonable size, anyway), you'd be hard pressed to add $100 to the
bill by wiring two completely separate circuits. Of course if you do
it that way I wouldn't recommend putting receptacles fed by two
different circuits in the same box. Same issue as with the shared
neutral circuit if a duplex breaker weren't used.
- -
LRod
Master Woodbutcher and seasoned termite
Shamelessly whoring my website since 1999
http://www.woodbutcher.net