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Is it possible to connect 2 motion detectors on a light circuit so it will sense movement coming from either direction?? Answered

What I'm trying to do is light a 50' long breeze way regardless of which end you enter. As it is now It only lights from 1 end. I'd think if you wire 2 motion detectors in parallel (Black-black, red-red, and white-white) then used the switched output (red) and neutral (white) to power the light it would work as I described. 

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iceng

2 years ago

Maybe this is easier to visualize.

wiring-daigram-dual-motion.JPG
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icengiceng

Answer 2 years ago

if you click on it !

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Toga_Dan

2 years ago

88 percent probability of success assuming that the power from each detector is in phase.

Highest likelyhood of a problem is if you've got power from 2 different circuits, and those 2 circuits are 180 degrees out of phase. That. Could. Be. Bad.

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Downunder35m

2 years ago

That only works if the motion detector is capable of being bridged by a light switch.
Most simply give the mains voltage out on the white line but have no protection for anything comin in this way.
If they use a relay that simply switches the mains voltage to the white line you have no problem.
Otherwise I recommend using a relay on each motion detector.
Problem either way is that the light is activated twice, so you might want to use quite low timing settings.

Another approach could go like this:
Get a timer relay that won's restart the timer with a new signal.
Some offer a switch for that function but the most basic ones don't.
A good alternative can be these timers used for the lights in staircases of the old kind.
They always did what noone wnated: No matter what you tried the lights had to go off before you could turn them back on.
Hard to find these days but sometime you get lucky at a garage sale.
With the motion detectors set to the lowest timing or testing setting you can now use their relay output to start the timer relay.
Great thing is that the light always stays on for the same amount of time, bad thing is that with a lot of traffic it might go off when you don't want it off.

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icengDownunder35m

Answer 2 years ago

Here is a circuit that does not need a manual switch !

wiring-daigram-dual-motion.JPG
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iceng

2 years ago

I would wire the two motion detectors as below and added an override switch.

Be sure to click the pic to see the whole image...

wiring-daigram-dual-motion4.JPG
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steveastrouk

2 years ago

Can't say with certainty without seeing the insides of the units, but it sounds plausible.