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Old 01-23-2010, 07:55 PM   #1
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Add new light and switch to a switch loop


I understand that both wires in a switch loop are hot, so there is no neutral wire. What I want to do is replace the single switch in the existing box with a double gang (two switches stacked vertically) with the tab removed.

I had thought that I could attach two pigtails to the black incoming wire from the existing light fixture. One pigtail would be attached to the top switch's hot screw and the second pigtail attached to the bottom switch's hot screw. Then I would attach the black wire in the cable going to the new light fixture to the light-colored screw of the bottom switch and the white wire in the cable going to the new light fixture to a pigtail. This pigtail would attach to the light-colored screw of the top switch and to the outgoing white-coded-black wire to the original light fixture.

Will that work and meet code, or do I have to pull power from another unswitched location to the new light fixture, and then to one of the two switches in my gang?

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Old 01-23-2010, 07:58 PM   #2
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Add new light and switch to a switch loop


You have not neutral. You can 't do it. Power comes from the light on the white and return as switched power on the black. Where were you thinking you could get the neutral for the new fixture. By attaching the existing white to the new white you have provided two hot wires to your new fixture. You need to replace the cable from the existing light to the switch with a three wire cable. There are no magic tricks to do it any other way unless you bring a new power feed to the switch or the new fixture.

Also those two switch devices don't need two hot wires. There is a set of screws on one side that is common to both switches. Connect one hot and both switches are powered.

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Old 01-23-2010, 08:19 PM   #3
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Add new light and switch to a switch loop


I understand that the tab on the side of the double-gang switch is common to both switches, which is why I wanted to remove it.

Without breaking the tab, I experimented by attaching a light bulb in a plug-in socket to a length of 2-wire+ground cable, and could switch the bulb using the bottom switch. The problem was that, with one wiring method, I could get the new fixture on only if the original one was on. With a different method, I could only get the new one on if the original was off.

Is this because the new fixture lacks the neutral wire?
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Old 01-23-2010, 08:23 PM   #4
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Add new light and switch to a switch loop


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Originally Posted by joed View Post
You have not neutral. You can 't do it. Power comes from the light on the white and return as switched power on the black. Where were you thinking you could get the neutral for the new fixture. By attaching the existing white to the new white you have provided two hot wires to your new fixture. You need to replace the cable from the existing light to the switch with a three wire cable. There are no magic tricks to do it any other way unless you bring a new power feed to the switch or the new fixture.

Also those two switch devices don't need two hot wires. There is a set of screws on one side that is common to both switches. Connect one hot and both switches are powered.
But the breakaway tab is still provided (even though 90% of the time they're used the way you describe). I believe it's there for jobs where you had 2 completely independent switches in the first place!!
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Old 01-24-2010, 08:58 AM   #5
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Add new light and switch to a switch loop


Tab is there if you have two switches on two different circuits. Not a very common situation.
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