add a switch to 2 single pole switches

I have an electrical box with 2 single-pole switches coming from the same power source. I want to convert one of the single pole switches to a dual switch that controls two different lights. I have a dual switch, but am not sure about the wiring. Could anyone provide some help.

Thanks

TC

 

These directions are dependent on your correct assessment of the existing wiring. If you correctly analyzed the existing wiring, there should be three black/white cables coming into the switch box, one is the power feed and the other two go to the two things controlled. All three white wires should be connected to each other and no white wires should be connected to either switch. Unless what you have matches this description, stop now, as you have not correctly identified the situation. Provide more details.

You will add one more black/white cable from this switch box to the new light.

Take the power feed black wire off the switch you are removing and connect it to the common side of the new duplex switch. The common side is the side with the tab that connects the two brass screws. Use either one of the screws. Now take the other black wire (the switch leg) off the old switch and conect it to either screw on the other side of the duplex switch. Then connect the new black wire to the new light to the remaining screw on the non-common side of the duplex switch. Connect the new white wire of your new cable in with the other white wires.

 

Here is additional information from TC which I found in the electrical forum.

I have a box with two single pole switches on one breaker. I want to add another switch that converts one single-pole switch to two switches so that I can control three light sources. I installed a combination 2 single pole switch, following instructions, but only the original single-pole switch and the top of the combo switch work.

One single-pole switch has three wires and the other has two. I tried converting the two wire having the hot wire coming into the combo switch and piggying to the single-pole switch (instructions say only have the hot wire connected to the top of the combo switch). Each common wire from both lights are attach to their respective switch and tied into the source.