Correct way to run neutral conductor.

[Shriimpboat]

I am currently in school learning the trade and there is a difference of opinion on the correct way to run the neutral in a certain situation. We are running two metal boxes each with two three-way switches. The feed is coming in one box and feeding the first set of three-ways, A, and B. Then we are running two MC cables to the second box and connecting them to the second set of three-ways, A, and B. Lastly, each switch is controlling a single light, A, and B. My question is, Where do I connect the neutrals? Is it ok to use one 12/2 as travelers and one 12/3 as travelers and a neutral and splice the neutrals in the second box, Or do i need to run two sets of 12/3 and have a neutral running with both sets of travelers originating in the first box where its connected to the home run? I have drawn a picture in case I haven't explained it clearly enough.

 

[kwired]

I am currently in school learning the trade and there is a difference of opinion on the correct way to run the neutral in a certain situation. We are running two metal boxes each with two three-way switches. The feed is coming in one box and feeding the first set of three-ways, A, and B. Then we are running two MC cables to the second box and connecting them to the second set of three-ways, A, and B. Lastly, each switch is controlling a single light, A, and B. My question is, Where do I connect the neutrals? Is it ok to use one 12/2 as travelers and one 12/3 as travelers and a neutral and splice the neutrals in the second box, Or do i need to run two sets of 12/3 and have a neutral running with both sets of travelers originating in the first box where its connected to the home run? I have drawn a picture in case I haven't explained it clearly enough.

Has anyone you are debating this with brought up 300.3(B)?

Are the cables in question routed in close proximity to one another?

Are they non ferrous sheathed cables?

 

[Shriimpboat]

Has anyone you are debating this with brought up 300.3(B)?

Are the cables in question routed in close proximity to one another?

Are they non ferrous sheathed cables?

We have not talked about 300.3(B). I don't have my book on me so I'm not sure of what that is. The cables are right next to each other and they are run in MC Lite aluminum sheathed mc cable.

 

[infinity]

Here is is, this does not meet one of the items mentioned in (B)(1) through (B)(4).

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 con-
ductors shall be contained within the same raceway, auxil-
iary gutter, cable tray, cablebus assembly, trench, cable, or
cord, unless otherwise permitted in accordance with
300.3(B)(1) through (B)(4).

 

[Shriimpboat]

So are you saying that the picture on the right is the correct way to do it?

 

[mbrooke]

The one to the right.

 

[Shriimpboat]

Thank you

 

[kwired]

I will admit to having done similar installations, but typically with NM cable and the cables in question are routed together for their entire length. May not quite meet the code but the main intent is to keep all conductors of the circuit in close proximity to one another to lessen EMF's and to reduce conductor impedance - especially in short circuit/ground fault conditions. Old knob and tube wiring was a bigger problem when it comes to meeting those goals as those conductors are not always in close proximity to one another.

 

[xformer]

neutral conductor

neutral conductor

If we take the drawing on the right and add a hallway between the sets of three-ways and add a 4 way. Does the Neutral have to accompany the conductors to the 4 way?

 

[mivey]

I am currently in school learning the trade and there is a difference of opinion.

Why? The instructor should be a good source to settle it.

 

[mivey]

If we take the drawing on the right and add a hallway between the sets of three-ways and add a 4 way. Does the Neutral have to accompany the conductors to the 4 way?

Of course. There is no balancing return current otherwise (like you would have with a return hot with fixtures at the top end).

 

[GoldDigger]

Why? The instructor should be a good source to settle it.

1. The instructor is always right.
2. But the inspector disagrees with my instructor.
3. Like I said, the inspector is always right. (Or at least so dereckbc reminds me. )

 

[Smart $]

Here it is, this does not meet one of the items mentioned in (B)(1) through (B)(4).

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 con-
ductors shall be contained within the same raceway, auxil-
iary gutter, cable tray, cablebus assembly, trench, cable, or
cord, unless otherwise permitted in accordance with
300.3(B)(1) through (B)(4).

Not sure whether you saw it before you posted, but he said using MC Lite aluminum. That qualifies as a nonmagnetic sheath wiring method under 330.3(B)(3). However, unless a double MC connector is used at each box, 300.20(B) will require slots be cut between KOs if the boxes are ferrous.