ECN Forum Forums Code Related Discussion NEC & other Code issues One Neutral For Multiple Circuits

Anyone ever do this?

I see it..no i have not done it...but i can be taught!

I sure didn't mean to abruptly change the subject. Glad Tom B. got his answer.

I thought about mounting a neutral bar in a lighting control cabinet (once while I was looking like a meatball in a bowl of spaghetti). Cabinet was connected by a 2' nipple to the panelboard, and I was going to extend the neutral feeder up to the neutral bar. I didn't, but never could think of a reason that I couldn't.
I'd be glad to hear of a reason why not.
Scott T - You're right, it would look really stupid

Not unless its 3 phase. 2 ckts on the same phase will draw twice the current on the neutral

Probably the wiring rule is this regard could be stated that any circuit breaker should be able to be replaced with a GFCI or AFCI. If you have several CBs for the UGCs, then you can't do that with a shared neutral.

And if your sleeping area is wired with three phase, you'll need three-pole AFCIs.

Aldav 53,
Under the conditions stated, Tom B would have to have "4 phase" for 1 common neutral of the same size as the phase conductors to supply 4 circuits.(including bathroom GFCI)

What exactly is the difference between NM and NM-B?

NM was manufactured with 60 degree insulation and NM-B is manufactured with 90 degree insulation. The NEC Article 336, Part C. Construction Specifications

See Section 336-30 in the NEC

[This message has been edited by Joe Tedesco (edited 10-15-2001).]

Listen to these guys! "Sharing" neutrals can be tricky, especially if something goes wrong, there is an "open" neutral created, you need to troubleshoot something, or GFI's are involved. The simplest, surest, safest way is to run a separate neutral for each circuit- then make sure that the circuits stay separate!
Sometimes, if you know enough to ask a question, you already know you're in over your head. That's why even the best new journeyman recognises that his education is just beginning!

The important issue to remember when running multiple circuits on the same neutral is to phase them properly. There is nothing wrong in running 12-3 to say, the refrigerator and branching off of it to a small appliance circuit provided you pigtail the neutrals at the refrigerator outlet and say, use the red for the refrigerator and the black (jointed in the box) to the other circuit. The neutral, being on different phases, will never draw more than the highest amperage of any particular phase. The overcurrent protection can be put on either a double pole 20 with a common trip or two single pole 20's with a "trip bar" that will trip both breakers if one trips.

C.
A "trip-bar" or handle tie will not always trip the second breaker if the first one trips. Only a common trip breaker will do this every time. While the use of a double pole breaker or handle ties is a good idea, it is not required by the NEC unless both circuits are on the same device yoke.
Don(resqcapt19)

Yes,
very evident in the use of nails to accomplish this...