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I have some motion lights in the back of my house, I want to also be able to use them to illuminate the back when I'm out there. I drew up the following schematic, the idea is to have the motion lights "on" when the switch is in one position, "constantly" on when the switch is in another position, and off completely when the switch is in the middle.

Is there anything wrong with my schematic? Is it ok to override the motion sensor this way? Do i have to worry about back-feeding it with power?

enter image description here


Side note: I come from the electronics world as a hobby and the only switch I could think of is called an SPDT, is there an equivalent version for home switches? I don't think its a 3-way switch as that is used when you have more than 1 switch (although I could be mistaken).

  • Most floodlight motion sensors have override mode built in. Usually to activate you flip the switch off and back on quickly. To restore motion mode turn off for 30 seconds then back to on. – Tyson Feb 27 '18 at 0:16
  • thanks tyson, i'm aware of that, i just don't particularly like that functionality – Alex Feb 27 '18 at 0:21
  • The SPDT is called a 3-way switch, or 2-way in UK. Severing power to the sensor may cause problems. Sensors have memories and if you bypass them, they may do silly things like take awhile to recalibrate when they come on again, or forget to disregard the nearby street light when calculating night or day, something it takes 24-48h to learn. Also, don't count on this method working on LED+motion sensor all-in-ones. Have you done a teardown on your unit to confirm it does work as you are anticipating? – Harper - Reinstate Monica Feb 27 '18 at 0:52
  • Good luck getting rid of the built-in functionality. What you’re suggesting should be no problem with some/many/most models. Some come with illustrations in the instructions showing how to make the same effective backfeed connection, except in the printed versions it’s how to interconnect multiple motion sensors. If one detects motion, the lights of all energize. Effectively the lights come on when the first motion trips, and go off when the last times out. – Tyson Feb 27 '18 at 1:05
  • i have a motion detector fixture that can be toggled on by flipping the switch off and back on quickly; and it's nothing fancy, just a regular unit from a box-store. That seems a lot simpler than rewiring everything... – dandavis Feb 27 '18 at 20:34
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The problem with a regular "3-way" switch it that it doesn't have an 'off' position where neither of the sides is connected. For that you'd need a 'center-off' switch like this one.

Then, as others have commented, it may not be a good idea to cut power to the sensor as t could take some time to get itself restarted and operational.

So, how about this instead:

schematic

This way, the sensor is always powered, but you're switching the light between the sensor's output and the always-hot line (with the off position in the middle).
The down-side is that you'll need an extra wire in the cable so that you can bring the sensor output back to the switch.

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The switch you show in your question will work as you want. Everything is fed from the same hot line so there would not be an issue. I would on off on or 3 position so the light could be turned off if needed, but a 2 position switch would also work.

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