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Residential Motion Sensor Placement

ccmichaelson

Active Member
For all you pro's out there, where do you normally install motion detectors (and what type) in residential bedrooms, living rooms, etc.  I will have an Elk M1 alarm panel and I plan to dual-purpose my motion sensors with lighting control (e.g. turn lights on/off).  I know that occupancy sensors are a more idea scenario but many have responded in previous threads that motion sensors -> alarm panel -> ISY -> Insteon switch round trip is typically less than a second which is okay with me and the boss ;-)
 
The other difficulty is that I don't know where my wife plans on hanging decorations on the walls or where we may have the finish carpenter install custom cabinets (e.g. in that corner where I was going to place the sensor).  
 
As I walk around my new construction house (just about framed), it seems like the best/safest option would be to place a ceiling mounted motion right above each door (ceilings are 10') as to trigger lights on as soon as you step foot into the room (or alarm if burglar in away mode).  The door will be about 6'8" tall so I can mount the sensor on 10' ceiling such that walking down the hallway won't trigger but you'd have to enter the room (or put your foot within a few inches of the door way).  Would I be happy with mounting a standard wall sensor (e.g. bosch blue light gen 2) above the door pointed towards the middle of the room?  Something tells me you'd have to walk 2-4 steps before the motion would trigger.
 
Appreciate any advice!
 

LarrylLix

Senior Member
Depending what you want the MS in the bedroom for, stand on the bed at the head facing the wall and at face level over the middle of the headboard it just about right to trigger lights for pee runs and not triggerring while in bed. A leg lift usually gets it too.
 
I placed many of these X10 MS units on the top of the picture frame over the bed with Uncle Harry on it.
 
 
Remember the most sensitive spot is where the motion cuts across the radial lines of view.
 
Ceiling mount PIR's offer less coverage and range compared to a properly sighted and installed wall/corner mount unit. You will not get an activation when you just "step into the room" with ceiling mount. For almost every install I've seen, you're going to be lucky to get coverage until you just about walk under it.
 
Ceiling mount PIR's are suited more for a commercial application where the FOV is going to be blocked by materials/displays or furniture, or changed often.
 
For the OP, I doubt your wife is going to mount decorations in the corner of the wall (although I may be surprised). Usually a good rule of thumb is about 1' below the top of the ceiling to allow for a crown molding install if you're really up in the air.
 
You would need to iron out the cabinetry details first however, as that is a significant change that can't be taken lightly.

What works for security is generally less than desirable for occupancy.
 

ano

Senior Member
DELInstallations said:
Usually a good rule of thumb is about 1' below the top of the ceiling to allow for a crown molding install if you're really up in the air.
 
We'll it also depends on high your ceilings are. Here 12' celings are normal, and 11' is way to high for motion sensors. They usually say 8' to 9' high.
 
Also keep in mind, Passive IR MOTION sensors are most sensitive when the motions is ACROSS to sensor, and not very sensative TOWARD or AWAY from the sensor.  Microwave sensors or the opposite of this.  Also, you never want the sun to shine on a sensor so they are generally best on the outside walls looking in.
 
As for occupancy sensor in the celing, yes in from of doors is best, but as you will soon discover, its easy to detect when someone enters a room, but hard to know if they still are in a room, so I'm not sure I would control lights with these.
 

ccmichaelson

Active Member
Here's an example of my issue...  My laundry room is roughly 8' wide and 15' deep with the entry door in the middle.  As you enter the room there are wall-to-wall cabinets on both sides with a window in the middle on the far wall so there's no corner to place a motion.  Since I'm planning to turn on the lights using motion detector my only option is ceiling mount.  If I placed the ceiling mount motion in the middle of the room and the door is open (highly likely) then if people walk pass the laundry room it would trigger the lights.   Seems like the best option is to ceiling mount it right above the door - although we have transoms (window above every door) so not sure if the ceiling mounted motion could "see" in the hallway and trigger.  Do typical PIR's "see" through windows?
 

ano

Senior Member
Like drvnbysound says, a simple wall switch is the best choice here, but use one of the Leviton Muti-Techology PIR/Ultrasonic switches. Even is the switch can't "see" the room because of cabinet or applicace placement, the ultrasonic part will detect people fine. I use several of thse and they work great. They even have a passthough mode so if you are just passing through an area, the lights quickly go out afterwards.
 
No, PIR sensors do not see through windows.
 

ccmichaelson

Active Member
I own several varieties of these Leviton wall switches with built-in motion and we hate them (they turn on when nobody in room, light setting difficult to get right, etc.)  More importantly, if I have a hard wire motion tied to elk and an Insteon switch & ISY controller I can be "smarter" about turning them on/off (I hope).  I'm going to purching an Elk today and get a couple different motions sensors and bench-test some motion sensors trigger lights in my current home just to see the delay, best placement options, etc.
 
Very much appreciate the feedback.  I still believe a ceiling mounted motion right above the door might be the best option although I'll need one that has a wide coverage area (most rooms are 10'-15' square. 
 
ano said:
We'll it also depends on high your ceilings are. Here 12' celings are normal, and 11' is way to high for motion sensors. They usually say 8' to 9' high.
 
Also keep in mind, Passive IR MOTION sensors are most sensitive when the motions is ACROSS to sensor, and not very sensative TOWARD or AWAY from the sensor.  Microwave sensors or the opposite of this.  Also, you never want the sun to shine on a sensor so they are generally best on the outside walls looking in.
 
As for occupancy sensor in the celing, yes in from of doors is best, but as you will soon discover, its easy to detect when someone enters a room, but hard to know if they still are in a room, so I'm not sure I would control lights with these.
You need to temper the location based on the detector itself, some have no mounting restrictions, only an angle adjustment based on the fresnel lens. Obviously, a reality check needs to be performed. Same holds true with sunlight. Used to be a larger issue but almost every detector on the market in the last 20 has had a pretty good white light filter from the factory.
 
Microwave detectors aren't really the opposite of a conventional PIR in detection. Microwave isn't really directional nor does it need movement across an element, generally, you walk into a space that has a MW detector, it's going to pick you up no matter what, unless the sensitivity is turned down (affecting range).
 
The problem with MW is it'll see through walls and glass if the gain is adjusted too high....not to mention if the building materials have a lot of metal in it, all sorts of havoc.
 
MW is great for absolute detection, but horrible for false alarms. Installed many of them for flight lines and fence lines.
 
For the OP, I think a single PIR mounted above the door is a bad idea for security purposes for the sake of occupancy detection. Do it right vs. a compromise on security and occupancy detection.
 
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