I'd like to control a porch light with both a switch and a motion
detector. Switch on, light on; switch off, light on motion detector.
I've come up with two ways to wire this using a 3 Way Switch (DPST,
right?). Here are diagrams of the hot side:
Incoming ------------- 3 Way Switch ------------ Light
Power | A | B Common
---- Motion ----
Incoming ------------ 3 Way Switch ---------- Light
Power Common | A B |
---- Motion ----
The second way would be easier to wire (less box fill at the switch),
but I think it wouldn't work, as it presents the Motion Detector with
120V at its output when the switch is in position B. I'm assuming the
Motion Detector will require a neutral and will be quite unhappy to
have 120V at its output. Is this correct?
Is everything OK with the first diagram?
It's single pole double throw or just 3way switch. Run your feed into switch
box, run three wire cable from switch box to motion sensor/light. In switch
box splice neutral wires(white) straight through to white of motion sensor.
In switch box put feed black wire on switch common terminal. put red and
black on two other switch terminals. At motion sensor splice black to black
and red to red wire of motion sensor, which is the wire going to the lamps.
Now in one position the power goes to sensor and in the other position it
goes to the lamps. You're diagrams may be correct but I'm dyslexic
Right, this is my second diagram. My concern here is about damaging
the motion detector when the lamp is on via the switch: I'm assuming
the motion detector will have 3 wires, white neutral, black incoming
power and red outgoing switched power. The above wiring means that
when the lamp is on via the switch, the motion detector will "see" the
following set of connections:
White wire Neutral
Black wire Unconnected
Red wire Hot
Is this OK for the motion detector? If not, would it be OK if the
Black wire were also hot? That would be easy to arrange by just using
a SPST switch.
You're making this much too tough. Wire up the motion detector as either an
add-on or as a replacement to the original porch fixture. Do nothing at the
switch. The switch should always stay on. Motion will turn the light on. If
you want to turn the light on without any motion, just flick the switch off and
then right back on. The lights will come on and stay on. To reset back into
motion detection mode, just turn the switch off and wait a few minutes before
you turn it back on.
I've got motion sensors all the way around my house and they all work this way.
Yes, what I want to do is non standard, but I have to redo the wiring
anyway, so it won't be that hard to execute, if I can figure out the
wiring. I definitely prefer the user interface I describe to the user
interface that overloads the "on" position of a normal switch (i.e. on
has two different meanings).
Basically what I need to know is this: if I take a stand alone motion
detector with three wires, white neutral, black incoming power and red
outgoing switched power, and I hook the white to neutral, the red to
hot and leave the black unconnected, does it damage the motion
Wire it like a normal light with two 3-way switches or one single pole
switch. Motion detectors often have a feature where it will remain on if
you flip the switch off and on. Do it again and it goes back into motion
detecting mode. No fancy wiring required.
Check out some of the current like of fixtures and motion detectors. I
believe you will be able to find what you want without changing any wiring.
I believe you can find one that switch off light off, switch on light on,
switch on again light controlled by motion detector.
Yes, another poster suggested this, and I had this when I rented. If
there were existing wiring I wanted to keep, I would definitely use a
product like this to avoid rewiring. However, I'm replacing the knob
and tube wiring anyway, so I can wire the circuit anyway I want. And
I prefer the functionality I described (on = on, off = motion
detector) to the functionality these retrofit products have. So all I
need to do is figure out the wiring.
BTW, it looks like I'll need to use a separate light and motion
detector, since I want a decorative ceiling mount light fixture, and
all the decorative exterior lights with motion detectors built in are
wall mount lights. I guess with ceiling mount a built in motion
detector would be obscured. I'll just install a separate ceiling box
a couple feet away for the motion detector.
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