My dining room has a box on each wall with a single pole switch (for exterior light) next to a three way switch (for dining room interior light) that I attempted to replace with new switches. After changing all four switches out, all of the lights (two exterior lamps, dining room, kitchen, hallway, and bathroom) go out when I flip the first single pole exterior light switch off. This switch has 3 black wires connected to it which I’ve identified as the exterior switch, exterior hot, and the third is carrying power to the other light sources. I’ve tried wiring it multiple ways but it’s gotten me nowhere. Does anyone have an idea as to why this one single pole switch is controlling basically all of the general lighting in my house? Not sure what I did wrong. Any help would be greatly appreciated. Thanks

  • Hello, and welcome to Home Improvement. This is NOT the time for "try it and see what happens"; what happens might be that you get killed. Please take a step back and give us a diagram of your wiring. Commented Jul 19, 2020 at 14:58
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    You probably connected the "hot" for the other switches to the switched side of your first switch. Did you take any pictures before you took it all apart? That's always a good idea. Commented Jul 19, 2020 at 15:08
  • No George I didn’t take any pictures beforehand, I wish I would have looking back now..
    – Eric Brown
    Commented Jul 19, 2020 at 16:18

1 Answer 1


First, don’t experiment i.e. trying random stuff “to see if that fixes it”. There are lots of combinations that will work and will kill you.

Second, you are quite close on identifying the wire’s operational roles. They are:

  • Hot from supply (always measures hot)
  • Onward power to other points of use
  • Switched power to the light

If the first and second are connected, then the rest of your house will work. And they should always be connected no matter what you do.

What’s driving you up the wall is that you are continuing a sloppy practice someone else started, which is using the switch itself as a junction block for unrelated things. (I.e. the connection between supply and onward).

Very few switches even have provision for 2 wires on the line screw; that generally forces you into using a “backstab”, which is a bad idea all around.

You may be better off obtaining wire, nuts and the other kit required to make this a pigtail connection: join the two important wires (supply and onward) under a wire nut, so you are not using the switch as a splice, and then have a third short wire hop from the splice to the switch. This will also make the circuit more understandable for the next person. (Who might be you!)

I pigtail most of my stuff for a different reason, most of my connections are in awkward locations. It is easier to pigtail the outlet on a bench, then at the box simply whip together supply, onward and pigtail with a wire nut.

  • Thank you I will try pigtailing it once I get some extra wire today, I don’t have any on hand. Thank you for the help, I really hope I can get this fixed
    – Eric Brown
    Commented Jul 19, 2020 at 16:22
  • @EricBrown - When you get extra wire for the pig tailing make sure to get the same wire gauge that is currently in the circuit. Most likely the current wiring is 14AWG but if it happens to be 12AWG you do not want to be making pigtails with the smaller sized 14AWG.
    – Michael Karas
    Commented Jul 19, 2020 at 16:37
  • Thanks Michael I’ll do that. Would it be safe to just go with 12AWG?
    – Eric Brown
    Commented Jul 19, 2020 at 16:45
  • @EricBrown Yes, 12 AWG pigtails are acceptable for both 12 and 14 AWG wiring. Commented Jul 19, 2020 at 17:06
  • Thanks Harper, I’ll be sure to let you guys know if it worked or not. Appreciate all the help
    – Eric Brown
    Commented Jul 19, 2020 at 17:12

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