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What cable is needed for dead end leg of 3 way lighting circuit?

What cable is needed for dead end leg of 3 way lighting circuit?

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Old 12-22-15, 11:14 AM
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What cable is needed for dead end leg of 3 way lighting circuit?

I want to rewire the switch for the hall/stair light - right now the power at the light with a regular single pole switch at the top of the stairs. I'd like to make it 3 way with a switch at the bottom. I presume I need to have 4 conductor cable from top to bottom to bring a neutral down, correct? (I was considering electronic switches along the likes of Lutron Maestros)

Problem is - no one around here in small town MN sells 12/4 or 12/2/2 cable. Can I run two cables of 12/2 to have my 4 conductors? Or is there no need to bring a neutral down and just use 12/3?
 
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Old 12-22-15, 11:23 AM
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If you wire as in the diagram below you only need 3-conductor cable to meet code.

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If you really need to use 4-conductor you can use ENT (AKA Smurf) and four wires. A plastic old work box can be drilled with a spade bit to take the connector.
 
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Old 12-22-15, 11:54 AM
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Or is there no need to bring a neutral down and just use 12/3?
That depends on what code you are trying to meet. A neutral in each switch box wasn't required till the 2011 NEC.

Problem is - no one around here in small town MN sells 12/4 or 12/2/2 cable. Can I run two cables of 12/2 to have my 4 conductors?
No, you cannot use two 12-2 cables. If you can't find what you need, order it.
 
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Old 12-22-15, 12:38 PM
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Can you recommend a vendor for 4 conductor cable? I'm guessing I need only 50 ft of it in 12 gauge... Probably looking at $3/foot, huh?

I might be better off bringing in power from the basement to the bottom switch and eliminating the dead end.

I better double check our code requirement first. I know it has the AFCI breaker requirements, so I assumed about the neutrals.
 
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Old 12-22-15, 12:48 PM
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No, much less than that per foot but a quick search revealed it's only available online in 250' rolls. Home Depot has free shipping.

Southwire 250 ft. 12/2/2 NM-B Wire-55048455 - The Home Depot
 
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Old 12-22-15, 01:19 PM
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I did see that - but I have no need for the 250'. That's actually where I buy the rest of my wire, but it's 60 mi away.

Local building center actually sells by the foot 12/2 & 12/3, but they don't carry 12/4. And if I remember right - they charge $1.25/ft for 12/3 - which is why I was guesstimating $3 for something as uncommon as 12/4!

 
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Old 12-22-15, 01:39 PM
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And why I suggested using ENT and individual wires.

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Old 12-22-15, 01:51 PM
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Note that 12/4 and 12/2/2 are different items. 12/4 has black, red, blue, white, bare (only one neutral possible). 12/2/2 has black, white, red, white/red stripe, bare (two neutrals possible, striped wire can be remarked hot if needed). HD will ship by UPS/FedEx to your home to save the 60 mile trip. The leftover 12/2/2 or 12/4 can be used anywhere 12/2 can be used -- future wiring projects.

You could do flex conduit and individual wires, but I really don't think that will be any cheaper or less work than the 12/2/2.
 
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Old 12-22-15, 01:57 PM
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Maybe I'm missing something but I don't see why you would need 4 conductors. The illustration that Ray provided shows the normal way of doing the installation and it only uses 12/3 which even provides a neutral in each box as required by code.
 
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Old 12-22-15, 02:10 PM
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Msradell, I'm missing his reason also.
 
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Old 12-22-15, 03:07 PM
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Maybe I'm missing something but I don't see why you would need 4 conductors. The illustration that Ray provided shows the normal way of doing the installation and it only uses 12/3 which even provides a neutral in each box as required by code.
You're right - I'm probably overthinking it...

The thought was - there is already an existing light at the top of the stairs with a switch beneath it. It sucks that there is no switch at the bottom of the stairs - the kids hate to go up in the dark. So I was thinking - two SPDT switches and a length of wire to bring a switch to the bottom of the stairs - and no more having to walk up the stairs in the dark. The power is upstairs, which would make this a "dead end", right?

I guess I could run a 12/2 wire from upstairs to the box at the bottom of the stairs, and then wire the rest of the circuit as ray2047's diagram, but it would probably use less cable to pull it from the basement.


Note that 12/4 and 12/2/2 are different items. 12/4 has black, red, blue, white, bare (only one neutral possible). 12/2/2 has black, white, red, white/red stripe, bare (two neutrals possible, striped wire can be remarked hot if needed).
I know they are two different items, but I guess I don't completely understand the difference, aside from one wire being different color between the two (blue vs red/white)... Out of curiousity - what are the different uses for the two?
 
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Old 12-22-15, 03:11 PM
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I make it a point not to wire lighting circuits in #12 wiring. Takes up too much room in the box and is just not needed.

Is your wiring already started in #12..... if so..... you'll need to continue in #12.
 
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Old 12-22-15, 03:36 PM
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I guess I could run a 12/2 wire from upstairs to the box at the bottom of the stairs, and then wire the rest of the circuit as ray2047's diagram, but it would probably use less cable to pull it from the basement.
Yes,, capping off the existing power and running new power to the bottom switch from the easiest/closest location would be a good way to do it.
 
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