Single gang box with three sets of wires


Old 01-14-16, 11:09 AM
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Single gang box with three sets of wires

Long story short, I need to know how to correctly make this connection: 12/2 + 12/2 + 14/2 in single gang light switch box. I'm using Leviton Decora switches if that helps.
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Old 01-14-16, 11:15 AM
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Welcome to the forums.

What are you connecting, how many switches, what's the breaker rating, ...?

Just plain need more information.
Old 01-14-16, 11:23 AM
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You need to identify the cables. They should be like this:

Source power in, cable up to light, another cable to provide power downstream.

If you are adding or replacing a switch, the wiring is easy, but you must know which cable goes to where.
Old 01-14-16, 11:46 AM
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The #14 should not be on the circuit if it is 20 amps.

Like Brian said, you need to know where each cable goes and it's function.
Old 01-14-16, 12:01 PM
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I went out of town for the holidays and my helper didn't follow my instructions. He hung all the drywall without labeling wires first. It's a remodel where we replaced the fuse box with a brand new breaker box. We ran all the wires but no breaker connections have been made yet. Is there a trick/shortcut to finding out which wire is which?
Old 01-14-16, 12:26 PM
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The easiest way.... the way an electrician would locate them is to use a fox and hound tester.
That involves clipping a tone generator on the wires at the switchbox and then follow them using an inductive tracer.

Old 01-14-16, 12:26 PM
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First off you need to identify which goes to the breaker box. Choose one of the cables and check for voltage. If dead connect the black and white to a switch. Turn the switch on. Change your meter to resistance and at each place you suspect the cable goes disconnect and check the cable there for continuity. To confirm it's the correct cable have a helper turn the switch on and off as you watch the meter. It should go between continuity and open.

It would be best to replace the #14 cable. If you don't you are going to have to use a 15 amp breaker.

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