Wire Gauge Question

Old 06-04-01, 07:07 PM
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From what I read in this forum it is ok to go from a smaller gauge wire (12/2) to a higher gauge wire(10/2). My question is can I go back to 12/2 again later in the circuit?

Just bought a house and am doing some rewiring. What I have is a double pole 30 amp breaker with 10 gauge wire in conduit going out to the garage (not GFI). (Black and Red wire connected to the breaker, White to neutral bar) Current circuit has two 12/2 gauge wires 15 amp outlets running off this line. (I already know I have to address this).

I am looking for an easy fix to get back to code. What I was planing is to replace the 30 amp breaker with a 20 amp GFI breaker in the main box, replace the 10 gauge wire from the main box to the first junction box with 12/2. Rewire all current contections in the circuit (using the current 10 gauge wire in place) to Black - Hot, White - Neutral and Red - Ground. I also planing on adding two more outlets in the garage and a light using 12/2.

I have traced the whole circuit and see no reason for the 30 amp 10 gauge circuit. The only reason I can think the circuit was put in for was the previous owner was planing to use some high power tools in the garage which I won't be doing.

Will this meet code???????????

Old 06-05-01, 09:23 AM
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There is no need to replace any of the #10 wire. Just replace the 2 pole 30 amp breaker with a 2 pole 20 amp breaker and add additional 12-2 to reach the new outlets. This will be a "multi-wire" branch circuit and will give you 2 20 amp circuits in the garage. Install GFCI outlets to replace the standard ones.
Old 06-05-01, 06:47 PM
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Remember that a multi-wire circuit, using 220 volts split into two 120 volt circuit creating a neutral must have the neutral wire and the grounded legs wire nutted separate from any device, thus not relying on the device not being removed or the circuit would not work. These neutrals must be wirenutted where the two circuits split, and not be connected to a device.

Good Luck


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