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Discussion Starter · #1 ·
Hi - I currently have a ceiling fan/light combo hooked up to a single pole switch that appears to be part of a switch loop (2 wires in switch box - white and black). I want to replace this with a fan and light dimmer, but I need an extra wire to split up the fan and light.

Can I just run another 12 gauge wire up to the light from the switch for the light portion of the dimmer? I can use the existing wire for the fan portion.

Am I missing anything? Thanks!
 

· Master Electrician
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...Can I just run another 12 gauge wire up to the light from the switch for the light portion of the dimmer? I can use the existing wire for the fan portion.

Am I missing anything? Thanks!
You can run an individual 12ga wire only if it's in conduit of some sort. If it's run with cable, you'll have to run another cable.

Have you thought of using a remote instead of running a new cable?
 

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Discussion Starter · #5 ·
My question was more about if this approach would work (running an individual line from the switch to the fan when the switch is currently part of a switch loop?

Essentially the fan power would be coming from the box in the attic (current wire) and the light power would be coming from the switch (new individual wire).
 

· A "Handy Husband"
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Can I just run another 12 gauge wire up to the light from the switch for the light portion of the dimmer? I can use the existing wire for the fan portion.

Am I missing anything? Thanks!
Is the existing wiring in cable or conduit? If conduit, you can run a single #12 THHN wire.

If cable, you will need a 12-2 cable. Power down to the switches on the 2 whites (re-marked black) and use the 2 blacks as switched power back to the fan and light.

If you are under NEC2011, this is non-complaint as you also need a neutral in the switch box (in this case run a (12-3 cable instead of 12-2, use the black and red for the hot and switched hot).
 

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Discussion Starter · #7 ·
Existing wiring is in cable (black and white wire in a white casing), so I was just going to run one insulated red 12 gauge wire from the switch to the fan.

But you're saying this won't work? Not sure I understand.
 

· Learning by Doing
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Elkie said:
Existing wiring is in cable (black and white wire in a white casing), so I was just going to run one insulated red 12 gauge wire from the switch to the fan.

But you're saying this won't work? Not sure I understand.
It's not that it won't work .... It's that it is NOT CODE COMPLIANT and it creates a hazard for anyone down the road.

Buy yourself a fan remote, install in 10 minutes and be done with it.
 

· Super Moderator
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To expand, all the conductors of the circuit need to be run together. adding another conductor outside the sheath would not comply with the rules. You could however run a new cable.
 

· A "Handy Husband"
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To expand, all the conductors of the circuit need to be run together. adding another conductor outside the sheath would not comply with the rules. You could however run a new cable.

Jim,

My suggestion was to run a new 2 wire cable and send the power down on the 2 whites (re-marked) black and use the blacks for the switch returns. That makes 2 different circuits (switch loops), one for the fan and one for the light. I believe that complies with the code requiring all conductors for a circuit be in the same sheath.
 

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I think the switch loop would need to be in the same cable, ie down and back in the same sheath.

All of this ignore the 2011 requirement for a neutral at each switch, whether needed or used or not.
 

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Jim,

My suggestion was to run a new 2 wire cable and send the power down on the 2 whites (re-marked) black and use the blacks for the switch returns. That makes 2 different circuits (switch loops), one for the fan and one for the light. I believe that complies with the code requiring all conductors for a circuit be in the same sheath.
I might have misread your solution, but one neutral return must remain white.
 

· A "Handy Husband"
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So as long as I run a new 14-2 cable and just use the black from the switch to the fan that would be ok?

I would just need to cap off the whites at both ends?
No that is not OK, that separates the circuit into 2 different cable sheaths and is a code violation.

Jim Port and I have a agreed to disagree on whether you can use both whites as remarked hots and use the blacks as the switch loop returns.

But since you need to run a new cable, run a 3 wire cable and get everything (both the fan circuit and light circuit) into the same cable. Abondon the existing 2 wire cable.

Unless you are under NEC 2011, then you need a 4 wire cable.
 

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No that is not OK, that separates the circuit into 2 different cable sheaths and is a code violation.

Jim Port and I have a agreed to disagree on whether you can use both whites as remarked hots and use the blacks as the switch loop returns.

But since you need to run a new cable, run a 3 wire cable and get everything (both the fan circuit and light circuit) into the same cable. Abondon the existing 2 wire cable.

Unless you are under NEC 2011, then you need a 4 wire cable.
rjniles, I am probably not reading the same Art Sec for the same cable same circuit requirement that would be permitted in resi work. The [300.5(I)Ex.1 is related to underground and does not include structure frame installation as mentioned in same circuit [300.3(B)(1)&(2)} for otherwise permitted further references to grounding.
 
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