I am changing a 2 in 1 switch that controls a light(top) and garbage disposal (bottom). They are controlled by different breakers. There was 3 wires in the old box. Black and red on top (different sides) and red on bottom, same side as black on top. I purchased a Legrand RCD33WCC6 paddle switch. When I wire red for light to top,black to common (Middle),and red for disposal on bottom. The light works with switch but disposal just comes on and stays on. What is wrong?

  • 2
    Nobody cares where the screws are located on the device. What matters is the markings that describe the screws' function, either as words near the screws, or the screw colors. Dec 20, 2018 at 18:39
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    Can you post a photo of the inside of the switch box please? Dec 21, 2018 at 0:27

1 Answer 1


If they are on different breakers, you can't use a switch with a common hot.

You need something like (picked at random by Googling "dual independent switch") Decora 15 Amp Single Pole Dual Switch. The instructions include removing a tab that connects the hots if you need separate hots - just like using a dual receptacle on two separate circuits.

WAIT A MINUTE!!! From what you described, the old switch only had 3 wires! That means it also had 1 hot, 2 switched hot. In which case it was not on 2 separate breakers. If that's the case, you just have the wires confused. Separate the 3 wires. Determine which wire is hot using a tester (non-contact should be sufficient if it gives a clear indication, multimeter is the best test). Then turn the breaker (singular!) off again connect the hot to the common screw and one at a time connect one of the other wires to a switch and see what happens. You should be able to track it down that way to determine which wire goes where and get everything working.


  • Screw location does not have anything to do with screw function. Each manufacturer, and each model within a manufacturer, can vary.

  • Color does not indicate function. It should, but often it does not. If things are wired (USA) according to code, you should find:

    • Green/bare = Ground
    • White/Gray = Neutral
    • Black/Red/other colors = Hot, Switched Hot, Travelers, etc.

So while typically black = hot, red = switched hot, there are no guarantees.

  • found the hot wire hooked up, still no good light works with one breaker flipped on but disposal doesn't work. It only goes on and stays on when I flip the second breaker on, not affected by switch
    – rich
    Dec 20, 2018 at 22:15
  • Do you actually have TWO breakers involved and only THREE wires in the box? Because if so something is seriously wrong. Like dangerously wrong. Dec 20, 2018 at 22:19
  • Yes only three wires! Sounds like time for a professional
    – rich
    Dec 20, 2018 at 23:00
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    If you truly have only 3 wires for the switches and two breakers definitely involved and you are really sure that's the way it was before, then the only way (really backwards) that I could see it ever worked would be switched neutral instead of hot plus breakers on same leg/phase, which would probably work but definitely break a bunch of safety rules. Which is even worse when you're dealing with kitchen = water = ground faults etc. Dec 20, 2018 at 23:14

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