Can you splice a 12 gauge romex into a 10 gauge romex?


Old 11-26-13, 04:02 PM
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Can you splice a 12 gauge romex into a 10 gauge romex?

I have a 10 gauge wire running directly to my 20 amp breaker and want to splice a 12 gauge wire into it in order to create an outlet for a range hood. Any issues in doing this? The 10 gauge has an extra red wire, do I just ignore this when splicing the 12 gauge and 10 gauge together?
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Old 11-26-13, 04:13 PM
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While there is nothing wrong with the practice, it gives the illusion at the range top end that you have a larger capacity than you do. Your max amperage protection will be the carrying capability of the smallest wire, 12 ga, or 20 amps. In the breaker panel cut the red wire back far enough to where it cannot be attached to another wire or to a breaker. Cut the red wire at the other end in the same manner. You will be making this connection in a junction box, left exposed and covered, right?
Old 11-26-13, 07:34 PM
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You are not required to cut off the red wire if you have space for it in your box. You may just leave it in there, caped off with a nut, as a spare wire.
Old 11-26-13, 08:01 PM
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I suggest not cutting off the red wire. Someone else might want to use it at a later date, for example converting back to 120/240 volt usage.

I suggest splicing on a short length (6 inches is enough) of the smaller gauge (12 gauge) wire to the end entering the panel. This reinforces that the circuit is a 20 amp circuit rather than a 30 amp (typical 10 gauge wiring) circuit.
Old 11-27-13, 06:25 AM
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Can you splice a 12 gauge romex into a 10 gauge romex?
Yes ............................................
Old 11-27-13, 10:05 AM
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Is it 10ga on a 20A breaker because it's a long run?

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