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Have 12/2, need 12/3. Can I just run single strand of 12 AWG? For light bulb.

Have 12/2, need 12/3. Can I just run single strand of 12 AWG? For light bulb.

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  #1  
Old 09-25-19, 04:14 PM
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Have 12/2, need 12/3. Can I just run single strand of 12 AWG? For light bulb.

Have bath exhaust fan where the switch controls both at the same time. Want to split it up, so 1 switch for fan, 1 switch for light. Need 12/3 wire to do that, but I have some single strand 12 AWG... can I just use that to run the light?

 
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  #2  
Old 09-25-19, 05:19 PM
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No you can not.
All conductors for a circuit must be in the same cable jacket or conduit if single conductors.

The wire pictured does not even look like AC circuit certified wire(THHN).
 
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  #3  
Old 09-25-19, 07:26 PM
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While you cannot run a single wire, you can just pull additional 12/2 instead of replacing existing cable to 12/3.
However, this may not make a difference unless you already have 12/2. It will be about the same amount of work to pull 12/3 anyway and just abandon existing cable.
 
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Old 09-25-19, 09:16 PM
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An additional 12/2 would not be compliant. The hot and neutral would be in different cables since the fan and light share the neutral at the fan.
 
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  #5  
Old 09-25-19, 09:26 PM
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Most cheap fans I saw had separate neutral wires for the light and fan. It probably is different with high end ones?..
 
  #6  
Old 09-26-19, 06:22 AM
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L and N need to be in the same raceway. In order to cancel their mag fields and not cause inductive heating to nearby magnetic metals (boxes, conduit, etc).
Multiple N are ok, again when paired with its corresponding L.
 
  #7  
Old 09-26-19, 06:47 AM
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If the fan and light have separate neutrals you are fine. If they share a neutral you you can't do it. Parallel conductors are not permitted below #6 and even then they need to be in the same conduit.
 
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Old 09-26-19, 04:33 PM
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Parallel conductors are not permitted below #6
Parallel conductors are required to be #1/0 or larger and can be in separate raceways or cables. 310.15(H)(1) and (3)

Wires smaller than 1/0 can be paralleled but they are required to be able to carry the entire load current. 310.15(H)(1)(b)

You can run 2 - 12/2 cables and parallel the neutrals if need or run separately to each part of the fan/light.
 
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