Setup: Two Switches for one light, one downstairs and one upstairs in a stairwell.

Old Switch Wiring (black is in common of switch)( same type of switch upstairs)

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New Switch: Lutron Maestro Motion Sensor switch, 2-Amp, Single-Pole, White


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So here is the interesting part

With upstairs switch down, black wire from wall to green of new switch causes the new switch to click/switch but no lights

If the switch upstairs is up then the earth grounding wire (to the new switches green wire) works(light turns on) (when upstairs switch is down it doesn't light up)

Any ideas?

Edit: Updated some wording to make it more clear

  • 1
    I don't understand your problem description. For example, what does "bare grounding wire works" mean? Are you randomly connecting wires?
    – isherwood
    Mar 23, 2018 at 13:54
  • The switch instructions says to tie the earth ground to the green and bare wire on the switch so that's why I am doing that. When I say the "bare grounding wire works" in this case works means it's switching the light.
    – Daniel B
    Mar 23, 2018 at 13:59
  • I think you're misinterpreting what's happening. Grounding conductors don't switch anything, normally. They're a backup return path for current and don't carry current unless something goes wrong.
    – isherwood
    Mar 23, 2018 at 14:01
  • Ok I see, but I mean that's what's happening. So If I cannot use use the earth ground to the green wire of the new switch and the black wire dosent switch the light on or off (but you do hear the switch's relay clicking). So what should I do? do I need to pull one of the other wires in the box out?
    – Daniel B
    Mar 23, 2018 at 14:11
  • 1
    If I said "3-way switch" would you know wht I was referring to? Did either switch work the light before? Mar 23, 2018 at 18:47

1 Answer 1


That switch won’t work in a three-way application. The Lutron website has an FAQ which includes this question. Here is the answer:

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