My house has a double switch that is controlling 2 different lights (A and B). However, when I turn either one of the switches on, both lights turn on. Can somebody explain to me why this isn't working as expected?

I drew a diagram showing how it is wired. I am really confused because it should work as it is... Oh, and all 4 of the red twist caps are actually in the same box.

enter image description here

  • 2
    "Can somebody explain to me why this isn't working as expected?" How it is supposed to work and how you expect it to work may not be the same. How do you expect it to work ?
    – Alaska Man
    Jun 27, 2019 at 19:45
  • I expect switch A to control light A and switch B to control light B. Jun 27, 2019 at 19:54

1 Answer 1


You disregarded a feature these switches have, where one side of both switches are wired together. They can be separated by breaking a tab, but you didn't.

enter image description here


This side is intended to be the "common" side, so you could accomplish the left side of your diagram with one wire. However you placed it on the right side, where it shorts the output of both switches.

Just rewire to suit, or break off the tab.

  • Thank you! That worked! I ended up rewiring it instead of breaking the tab. Jun 27, 2019 at 20:53

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