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-   -   Switch Legs - Need Neutral, Can I....? (http://www.diychatroom.com/f18/switch-legs-need-neutral-can-i-178263/)

herdfan 04-28-2013 08:52 AM

Switch Legs - Need Neutral, Can I....?
 
Ok here is the problem. I need to put devices that require a neutral into a box that has 2 switches, both on the same circuit. Here is what I am thinking.

Switch A controls the porch light and Switch B controls the entry light and both have switched legs with no neutral in the box. I would like to feed both circuits from the porch light hot and use the entry neutral as my neutral.

I will try to explain in detail so hopefully I am clear.

Hot feed from porch light comes into Switch A. I would pigtail it and feed both Switch A & B. The current return leg from Switch B would be changed at the fixture and wired to the neutral (it is already a white wire). Then the old hot leg to Switch B would be the new return leg to B. Since both lights are on the same circuit, is this doable? Code compliant?

Thanks

k_buz 04-28-2013 09:05 AM

No, technically that is not legal.

The circuit conductors must be grouped (hot and neutral with the exception of switch loops). Since you are bringing the hot down one cable and the neutral down the other, the circuit conductors are not grouped.

k_buz 04-28-2013 09:07 AM

300.3 Conductors

(B) Conductors of the Same Circuit. All conductors of
the same circuit and, where used, the grounded conductor
and all equipment grounding conductors and bonding conductors
shall be contained within the same raceway, auxiliary
gutter, cable tray, cablebus assembly, trench, cable, or
cord, unless otherwise permitted in accordance with
300.3(B)(1) through (B)(4).

stickboy1375 04-28-2013 09:09 AM

Quote:

Originally Posted by herdfan (Post 1168617)
Ok here is the problem. I need to put devices that require a neutral into a box that has 2 switches, both on the same circuit. Here is what I am thinking.

Switch A controls the porch light and Switch B controls the entry light and both have switched legs with no neutral in the box. I would like to feed both circuits from the porch light hot and use the entry neutral as my neutral.

I will try to explain in detail so hopefully I am clear.

Hot feed from porch light comes into Switch A. I would pigtail it and feed both Switch A & B. The current return leg from Switch B would be changed at the fixture and wired to the neutral (it is already a white wire). Then the old hot leg to Switch B would be the new return leg to B. Since both lights are on the same circuit, is this doable? Code compliant?

Thanks

What type of wiring method?

k_buz 04-28-2013 09:11 AM

Quote:

Originally Posted by stickboy1375 (Post 1168632)
What type of wiring method?

My answer was based on the assumption of NM.

stickboy1375 04-28-2013 09:20 AM

Quote:

Originally Posted by k_buz (Post 1168634)
My answer was based on the assumption of NM.

Seems that any EMF's would still cancel out with the OP's scenario...


{edit}
Eh, the cable with the ungrounded conductor would not cancel out if that load was not on....

k_buz 04-28-2013 09:24 AM

Quote:

Originally Posted by stickboy1375 (Post 1168639)
Seems that any EMF's would still cancel out with the OP's scenario...

What if that "feed" was extended to power something else? True, the current on that neutral from the lighting control is almost negligible, but if that was ever used to feed a receptacle or additional lighting, there might be a much larger imbalance.

stickboy1375 04-28-2013 09:51 AM

Quote:

Originally Posted by k_buz (Post 1168645)
What if that "feed" was extended to power something else? True, the current on that neutral from the lighting control is almost negligible, but if that was ever used to feed a receptacle or additional lighting, there might be a much larger imbalance.


If everything in the OP's scenario is non- metallic, I say he is good to go, although he will be creating EMF's, but thats another non NEC issue...

k_buz 04-28-2013 09:53 AM

So, how is this not a 300.3 violation?

stickboy1375 04-28-2013 09:58 AM

Quote:

Originally Posted by k_buz (Post 1168664)
So, how is this not a 300.3 violation?

read 300.3(B)(3), it is an exception to 300.3.... and if all plastic boxes are used, 300.20(B) is null....

Jim Port 04-28-2013 09:58 AM

I think he is talking about the exception if a non-metallic wiring method is used. I am not going to look it up, just off the top of my head.

stickboy1375 04-28-2013 09:59 AM

This is all ASSUMING the OP is dealing with non metallic material...

stickboy1375 04-28-2013 10:00 AM

Ever wire the travelers of a 3 or 4 way switch with just xx-2 wire instead of xx-3? same example....

k_buz 04-28-2013 10:02 AM

I don't see any exception, all I see is confirmation of my claim.

(3) Nonferrous Wiring Methods. Conductors in wiring
methods with a nonmetallic or other nonmagnetic sheath,
where run in different raceways, auxiliary gutters, cable
trays, trenches, cables, or cords, shall comply with the provisions
of 300.20(B)
. Conductors in single-conductor Type
MI cable with a nonmagnetic sheath shall comply with the
provisions of 332.31. Conductors of single-conductor Type
MC cable with a nonmagnetic sheath shall comply with the
provisions of 330.31, 330.116, and 300.20(B).

k_buz 04-28-2013 10:03 AM

Quote:

Originally Posted by stickboy1375 (Post 1168671)
Ever wire the travelers of a 3 or 4 way switch with just xx-2 wire instead of xx-3? same example....

No it's not the same. There is an exception in 404 for switch loops.


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