My house currently has two 3-way switch controlling a light at the downstairs entrance. I like to turn one of the 3-way switch located at the lower floor to a motion sensor wall switch.
I opened up the existing 3-way switch box and it has 3 terminals with
3 wires (black, red, white), how do I hook it up to my motion sensor switch which has 2 black wires and 1 green (ground wire)? My goal is to make the top floor switch either an independent switch, or "3-way" with the motion wall switch.
Actually, if you look, you'll find your three-ways actually have 4 wires
- red, black, white and bare copper (the ground)
The problem you're going to have is that a three-way switch actually works like this (bad ascii art coming up)
2 black 4 1 / o-----------------o \\ 6 black 7 8 white black ----o/ \\o-----------o(L)o-----------. o-----------------o | 3 red 5 | | white ----------------------------------------------------------'
Consider the "o"s to be the terminals on the switch body; the ground line is left off since it's not electrically part of the circuit. Each switch can move to either the 'red' connection (terminals 3 and 5) or the 'black' (terminals 2 and 4). The idea is if both switches are on the same line, the light will be on. Since they have to be on one or the other, changing just one switch can turn the light on or off, at either end.
Now if you replace one of the switches with the motion sensor switch, since it has only two connections (the black wires; again, the ground doesn't count, for our purposes), you could connect to either the red line or the black line, but not both.
2 black blk 1 / o---------x---[M]---. blk black 7 8 white black ----o/ `-----x------o(L)o-----------. o---------x | 3 red | | white ----------------------------------------------------------'
Let's say it was connected to the black line from terminal 2. A safety problem then arises, as it would be possible for the switch to be set to the black line, which would now be energized but unconnected in the other switch's box. To avoid the safety hazard, you would have to also disconnect and terminate the red wire at terminal 3 in the remain switch box - then all you have is a piece of wire running through the walls.
One of the things you don't say is how you want this to work. Do you want the light to go on and off with the motion sensor detection, but have the switch override it, so you can turn it on and leave it on? Or turn it off and leave it off? Or both?
I agree that the OP is unclear what the swtiching is intended to do.
As shown, in one switch position the light will come on only when there is motion. In the other switch position the light will never come on.
Another possibility is one switch position the light comes on only when there is motion. The other position the light is always on. To get that
- at the motion detector end connect the red to the black going to the light - terminal 5 to 6.
You could also connect it so both 3-way switches work but a motion detector will always turn on the light.
In the first diagram the white wire will probably connect to terminal 1 or 6. In any case, when you look at the existing 3-way switch, 2 terminals will be the same color and one will be different. The different color will be terminals 1 and 6. Keep track of which wire it is.
Manual is: http://12.153.20.74/manuals/595-4881-09J.pdf I like the idea of using the motion sensor as a over-ride, meaning it will be triggered on by motion but only comes off when I turn off the switch.
I was able to take some pictures showing what I have:
Existing wall switch (lower floor):
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Motion sensor switch:
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I like to replace the lower floor light switch to a motion sensor so it will trigger the light to "on" but turn off by either the manual override on the motion sensor switch or the upper level switch (no shown).
Simple. Go to the nearest borg and buy a 3-way motion sensor switch. Carefully follow the instructions that come with it -- you'll have to mess with the switch wiring at both ends of the circuit but there is nothing difficult involved. The ones that I've used were made by Eagle which I believe was stocked by Lowe's but there are others and all are essentially identical. BTW, I've found that the switches do not work properly with a load which is solely CF but they do work fine with incandescent -- some peculiarity of how operating current is provided to the detector circuitry in the switch, I'm sure.
It is possible that turn-on-with-motion, turn-off-manually is built into some motion-detector-switch. What happens when your switch comes on with motion and you turn it off. I presume you saw your switch stays on for an adjustable time. Check the manual for the 3-way version of the switch you have what happens when it turns on with motion and then the 3-way circuit is turned on and off.
It could be done with a relay, but that is a lot of complication.
As John said, you might want to use a 3-way version of what you have.
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