1 Three Wire carry 2 circuits

[avlanche]

Can I run 1 12/3 wire from panel to a switch box, and feed 2 circuits? Both are 15 amp. 1 for lighting the other for outlets.

If yes; which wire is used for second common? RED?

[Wgoodrich]

You must use a 240 volt double pole breaker with 15 amp rating of the breaker if you are using a 15 amp three wire cable.

The black is connected to one lug of the double pole breaker for the first hot wire and the red is connected to the second lug of the double pole breaker for the second hot wire. Then the white wire is to be used as a neutral for both hot wires. The white wire would be considered a shared neutral serving both the black wire as one 120 volt circuit and using that same white wire serving the red wire as the second 120 volt circuit. The bare wire in that three wire cable would also serve both 120 volt circuits.

Hope this helps

Wg

[Anonymous]

?woodrich? Is the d/Pbreaker a new code ruling for 2002 nec. code pertaining to 3 wire circuits. TY

[Wgoodrich]

No, the NEC has for years required a double pole breaker in a dwelling setting. I included the double pole breaker in my reply because I picked up a weakness in knowledge of the poster in doing multiwire branch circuits. I added the double pole mentioned to try and ensure the poster did not overload a white wire by using two hot conductors in sync with each other rather than measuring 240 volts between hot lines making that white wire a true neutral.

The NEC actually requires in a dwelling setting a double pole 240 volt breaker when a multiwire branch circuit serves a device with both sides of the multiwire circuit connected on the same yoke. Just didn't think the poster was ready for that tech talk at this stage of his quest. Taking note that the 96 and 99 also says the same as the 2002, see below a copy of the NEC that applies;

COPIED SECTION OF 2002 NEC;

210.4 Multiwire Branch Circuits.

(B) Dwelling Units. In dwelling units, a multiwire branch circuit supplying more than one device or equipment on the same yoke shall be provided with a means to disconnect simultaneously all ungrounded conductors at the panelboard where the branch circuit originated.

WG COMMENT:

There is a second rule that applies to this two circuits on the same yoke that applies both to commercial / industrial and dwellings concerning the neutral conductor of a multiwire branch circuit. See the following copied section that would apply;

300.13 Mechanical and Electrical Continuity — Conductors.

(B) Device Removal. In multiwire branch circuits, the continuity of a grounded conductor shall not depend on device connections such as lampholders, receptacles, and so forth, where the removal of such devices would interrupt the continuity.


WG COMMENT;

There are times when a person is trying to do a certain wiring design where I have question if they are really ready to do that. Instead of telling them to hire a pro, I tell them the answer they are seeking yet at times add in a simple part that is not part of the rules yet picking up the level a person is at in skills I feel a bit more protection for them in doing what they are wanting to do should be add protection. I want people to learn and be able to do it themselves yet at times I feel a need to protect them from what they don't know they don't know. It is a part of the learning process in experiencing their project. In this case the double pole breaker that I advised him is only required if both hot wires being 240 volts between are connected to the same yoke or device. In the poster's situation I don't yet know if he is doing this same device or splitting in a j-box and running two circuits from that point. If the circuit is split without a neutal connected to the same yoke with two hot conductors then the double pole breaker would not be required. If the two hot conductors are connected to the same yoke then the neutral wire must be pigtailed not relying on the device if removed and the double pole breaker would be required. I felt at this time all this info was more than the poster could handle without getting an information overload.

Hope this helps

Wg

[avlanche]

Yes that helps a bunch. Your insites to my project and skill level are right on the money. Top job.

BTW; I am planning on having a pro wire the panel. I was checking on some advice given to me.

Thanks again

[Wgoodrich]

Remember that the wiring in the panel is no more no less dangerous than the wiring of just one branch circuit. Fires occur more often in branch circuits than in panels. Death due to shock happens more often with a branch circuit than with a panel.

If you are going to do the branch circuits no reason why you wouldn't do the panel and service too. Just do your homework. Read the following links that should help you to help yourself accurately.

http://www.homewiringandmore.com/homewiringusa/2002/definitions/demandcalc02/DwlingDmdCalc02.html

http://www.homewiringandmore.com/homewiringusa/2002/maindwelling/meter/meter.html

Let us know if this helps

Wg

[avlanche]

Wow, that is going to take a few days to digest. Great info to have,very helpful.

Thanks for giving us a place to have real questions answered, without having to talk to a guy in an orange vest.

[Anonymous]

:!: Fully understand! great way to do business,makes alot of sense especially when were asking for help, think everyone knows you can call a plumber or electrician.Granted at time's there certainly a time & place to call in the pro's. Hey, keep up the good work we need it at time's :!: TY

[Wgoodrich]

Thank you both for your positive thoughts. Providing what you think good or bad informs us where we need to make changes to do better.

Good luck and thank you

Wg