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View Full Version : Dbl switch single gang box to a two gang box.. surprise!


Rookie4312
Jul 24, 2012, 09:28 PM
In my kitchen I installed track lights from the org. fixture. Well the switch was a dbl over& under. The lower switch for the garbage disposer. Simple replace single gang box with dbl and hook lights up to a dimmer switch, the disposer to single switch. Well my gas stove also runs off this. I can get everything to work but my disposer. Here is what I am working with 3 sets of wires. The disposer and the stove set are your typical,white,black,ground. The wire for the lights and my hot is 1 red,1white,1black,1ground. So to break it down, three sets of wires,two sets are your typical net. White, hot black, copper ground. The hot set has an extra red wire. I just want everything to work and I can not afford to damage anything or an electrician. Thanks for helping this rookie out.

hkstroud
Jul 25, 2012, 06:32 AM
I assume that you did not take note of how things were wired before you started. No supprise there.

The first question is, how is the 3-wire cable being used.

It may be two circuits sharing a neutral or it may be a switch loop from the disposal connection underneath the sink. All indications are that it is a switch loop but you need make sure.

If you have a meter, check for voltage between the black and the neutral (white) of the 3-wire cable. Then check for voltage between th red and the neutral. It you have voltage on both, it is two circuits sharing a neutral. If you have voltage on only one it is a switch loop, with the wire having voltage being the uninterrupted hot and the other being the return leg to the disposal.

If you do not have a meter, you can remove the breaker panel cover and see if the wire going to the breaker goes to a 3-wire cable. If it does then the 3-wire cable is two circuits sharing a neutral. You can also open the box for the disposal connection under the sink and examine the wiring there. If there is not a connection box then the 3-wire cable is two circuits sharing a neutral.

Or you can connect all the neutrals in the switch box with a wire nut. Connect the black of the 3-wire cable to a switch, connect the black of the 2-wire cable to the light to the switch. Turn breaker on. See it the switch turns light on. Turn breaker off. Remove the black of the 3-wire cable and connect the red. See if switch turns light on. If the 3-wire cable is two circuits sharing a neutral, the switch will turn the light on both times If the 3-wire cable is a switch loop, the wire that makes the light burn will be the uninterrupted hot from the disposal connection box underneath the sink. The other will be the return leg to the disposal.

After you have determined that the 3-wire cable is indeed a switch loop ,and determined which wire is the uninterrupeted hot, connect two pigtails to the hot with a wire nut. Connect the pigtails to the switches. Connect the black of the 2-wire cable to the light to one switch. Connect the remaining wire (red or black) of the 3-wire cable to the other.

If the 3-wire cable is two circuits sharing a neutral, post back.

If you did take note of the wiring of the two-in-one switch, you will have had one wire of the 3-wire cable going to one side of the switch, you will have had the other wire going to the other side and the black of the light cable on the same side. The wire going to the side by its self is the hot. Connect the two pigtails to that wire and connect to the switches.