I'm trying to replace 2 dimmer switches with 2 regular switches, each dimmer switch controls 2 pot lights.

Each dimmer switch has 2 black wires as well as a green wire which seems to be ground but I'm not sure (the green wires both connect to each other with a bare copper wire, see pics).

I have the first switch replaced and working just fine with a 3 pole switch (green went to hole labelled COM and black wires went to each end). However when connecting the second switch in the same fashion the breaker trips immediately when turning it back on. What did I do wrong?

wiring new switch old switch box inside


From what I can see, this is how it was wired before:

Switch 1 = S1, Switch 2 = S2

S1 "Off" side black is in a pigtail with S2 "On" side black (which has 2 wires from the wall connected to it as well).

S1 "On" side black goes into the wall.

S2 "Off" side black goes into the wall.

Greens are pigtailed together with bare copper.

This is how it's wired now with only S2 connected and working:

Green is going to COM.

Black that was on Off side is going to Off side.

Black that was on On side is going to On side.

Trying to do the same thing on the other switch as well trips the breaker.

  • Can you get us a better shot of the insides of the box? Jan 26, 2017 at 4:29
  • @ThreePhaseEel Tried adding a better picture there, not sure if that helps.
    – asandhu
    Jan 26, 2017 at 4:36
  • What's the make and model of the new switch? Can you show a photo of the back of the new switch?
    – Tester101
    Jan 26, 2017 at 11:55

1 Answer 1


Congratulations, you've created a short-circuit. You've connected the ungrounded (hot) conductor directly to ground through the switch.

the reason the second switch caused the breaker to trip, is because it was toggled in the "correct" orientation. If the other switch had been toggled, it to would have tripped the breaker.

What you need is a single pole switch, not a 3-way. Then you'll connect the green wire to the green grounding screw, and the hot wires to the other brass colored screws.

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