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bryank

join:2000-03-23
Plainfield, IL

Have a small electrical question

So I need to install two new breakers for electrical outlets in our loft area and new office. The reason for the new breakers is that when the house was built, I feel they overloaded a single 15a breaker which currently runs a bedroom, a bathroom, the office, and the loft (both outlets and lighting).

So in the loft area I am going to be installing a flat panel plasma and associated audio/video equipment and I would like this on it's own breaker; 15a or 20a using 12ga wire. In the office, will be running a desktop, two monitors, other little peripherals, and occasionally an oil radiated space heater.

The builder left an open 3/4" conduit from the panel to the attic which gives me perfect access to run my lines (which I have no problems with at all). My question is how many lines (12ga sized) can I put in this 3/4" conduit and which lines do I definitely need to run?

Here is my thought, obviously the two hot lines (black) and two neutrals (white); or do I need to run only one neutral? I would imagine the ground can come from the conduit as long as the return path is connected back to the panel, but should I run a ground line (green or copper) just in case?

A little input would be great. Thanks.


StillLearn
Premium
join:2002-03-21
Streamwood, IL
Reviews:
·AT&T Midwest
Three wires needed including a white neutral, as long as the wires are hooked to opposite legs. If you put the two breakers one atop the other, then you should be good. The norm is to have the breaker panel zig-zag the legs. If you have conduit, no green protective ground wire is needed.

You have plenty of room to run a second pair of three wires. That way you could have a higher power heater without worrying about being able to power everything at once.

While doing the project, consider changing a 2-inch box to 4-inch. Have more outlets.


Msradell
P.E.
Premium
join:2008-12-25
Louisville, KY
said by StillLearn:

Three wires needed including a white neutral, as long as the wires are hooked to opposite legs. If you put the two breakers one atop the other, then you should be good. The norm is to have the breaker panel zig-zag the legs. If you have conduit, no green protective ground wire is needed.

No green ground wire is needed if the conduit is hard wall metal conduit. If it is PVC, a ground wire is needed and is it is ENT a ground wires needed unless there are ground jumpers in each joint!


leibold
Premium,MVM
join:2002-07-09
Sunnyvale, CA
kudos:10
Reviews:
·SONIC.NET
reply to bryank
A shared neutral may be permitted but since those circuits are going to different locations (loft and office) I would advise against it and run separate neutrals.

Local codes are sometimes stricter then NEC and may prohibit the shared neutral anyway.
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Red_Menace
poking around since 1978

join:2001-11-03
Littleton, CO
reply to bryank
You can put a bunch (16) of #12 THHN wires in 3/4" EMT, although you will need to derate for more than 3 current carrying conductors.

tedmarshall

join:2000-12-02
reply to leibold
said by leibold:

A shared neutral may be permitted but since those circuits are going to different locations (loft and office) I would advise against it and run separate neutrals.

Local codes are sometimes stricter then NEC and may prohibit the shared neutral anyway.

Also, AFAIK, you cannot easily use GFCI/AFI breakers with a common neutral.


jack b
Gone Fishing
Premium,MVM
join:2000-09-08
Cape Cod
kudos:1
reply to bryank
The only way you can share a neutral is if you make it a multi-wire branch circuit, using a (240v) twin breaker with a bonded handle, so that it has the two hots on different phases. Otherwise you will overload the neutral which can start a fire being there is no overload protection on the neutral.

So for a MWBC circuit run 4 wires: two 12GA hots, a 12GA neutral and a ground.
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