Wire guage question

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  #1  
Old 03-28-05, 06:04 AM
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Wire guage question

I would like to move an interior light switch, and need to extend the wire to reach the new switch location. My interior home wiring is 12G aluminum wire, ending with COPALUM connectors. I think that this light is on a 15 amp circuit. I have read that light switches should be run with 14G wire (copper).

What is the proper guage of wire to run in this circumstance?
Is the existing wire thicker because it was aluminum?
Would there be a problem with running 12G copper wire?

I live in Maryland. Thanks in advance.
 
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Old 03-28-05, 06:19 AM
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15 amp circuits are run with 14 gauge copper wire. 20 amp circuits are run with 12 gauge copper wire. Aluminum wire, as in your case, requires a larger wire size. This is why you have 12 gauge wire on a 15 amp circuit.

How do you plan on extending this circuit? Are you going to run a wire from the current switch location to the new location, or are you going to try to rewire all the way back to the light? Is this a switch loop or does power run into this box and then to the light?

Remember that you can't have splices unless they are located in a junction box. If at all possible, I would try to replace the wire all the way to the light. Yes, you can mix the aluminum wire with copper wire, but you need to make sure that the wires are joined with approved methods, you can't simply connect the wires with a wire nut.

Please be very careful with aluminum wire. Properly used it is safe, but improperly used and it becomes a fire hazard.
 
  #3  
Old 03-28-05, 01:58 PM
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Thanks for the reply.

The existing wiring has been modified with COPALUM connectors, so there's a copper wire terminus at each one. I plan to just use a twist-on connector to connect these to the new wire, and to run wire from the existing switch to a switch in a new location. I won't be joining copper to aluminum.

I don't know yet if it's a switch loop. Why does that matter?
 
  #4  
Old 03-28-05, 06:21 PM
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If it's a switch loop it's easier to disconnect and run a new wire.

If you leave the existing junction box in place then you need to install a blank cover over it and have it always accessible.
 
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