Motion Sensor Locations?


Active Member
I need some help figuring out where I should put some motion sensors. Here is my floor plan; can someone recommend the ideal location for motion sensors? So far I’ve only mounted one in the laundry room to use for turning on/off the light. When my original security system was installed all they used were glass breaks. I want to use the motion sensors for both HA turning on/off the lights and security.

If it'll be easy to run wires, I'd just as soon put one in every single room, pointed at either the entry/exit location or the location where there'd be the most activity. They're certainly cheap enough ($20 each), I see no reason to do anything less.
Ok so if I had a room sort of like this one where would I want to put the sensor so it isn't triggered walking by the door but still catches the motion as soon as you enter the room?


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If this was a map, i.e. North up, etc. I would put it in the NE corner. However, there are variables such as are the motions IR, Microwave, etc. But I think you would get the best bang for your buck in that corner. You could put it in the SE corner but I'm afraid of the door shielding the motion.

Edit: When I expanded the drawing, I was able to see it was a pocket door. Forget what I said about shielding in this room but watch out in other rooms.
IR motion detectors work best at detecting things moving across their field of view, rather than toward or away from the sensor. Try to avoid aiming at windows or other heat sources that may produce false alarms.
I'm just getting started, and I haven't even decided on which brand controller or sensors to use yet. I have decided I will play with the system for a while before I mount anything permanently. I expect to try a PIR in several places in a room and see which gives reliable response before I screw it to the wall or ceiling and bury the cable. It will also give me some experience testing pet immunity. Nothing better than testing in the actual environment to get it right.
To avoid false alarms use only the combination IR and Radar sensors. The IR ones can see through windows and the Radar ones can see through walls. Using both systems helps eliminate the false alarm problem.

Ceiling fans will cause false alarms with the Radar ones and heat from heat vents can cause false alarms form the IR ones. Also, drafts will false alarm the IR ones.

For best detection take the above into account and point the sensor away from potential false alarm sources. It is far better to have a slightly delayed response than a false alarm.

Pets are always a problem. Don't use a motion detector with a cat as when you are away they like to jump up on anything they can reach. If you must leave the cat inside restrict it a area where you don't have a motion detector.

Cliff s
Is it really true that having a cat negates the possiblilty of using PIR's? That is going to make my installation cheaper :ph34r:
Cats that jump really high can set off even pet imune motion sensors.

I've had very good luck with some dual tech (pir/microwave) units from Rokonet. The COSMoS Pet DT (RK111PT) has been very reliable in my home and a couple clients who have pets. They won't trigger if a cat jumps up to table or counter top height, but will probably still go off if you have a cat that goes from ground level to abouve 4ft very quickly either by jumping or making a few quick consecutive hops.

No false triggers so far with any of my systems but YMMW depending on the feline(s).

As others have mentioned, placement makes a big deal for motion sensors and ideal location may be different depending if they'll be used strictly for security, or if you'll also be using them for automation.

Photon said:
I have decided I will play with the system for a while before I mount anything permanently. I expect to try a PIR in several places in a room and see which gives reliable response before I screw it to the wall or ceiling and bury the cable.
I guess I should have done that as well. The one I mounted in the laundry room doesn't work very well. I have a Bosh Blue Pet Friendly one but maybe I could try something else? If you take a look at the picture I mounted it where the red circle is but when you come in the door with the arrow and go to the washer/dryer it doesn't always come on. The main reason for this one was to turn on the light for the wife when she goes in there.


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It's kind of hard to tell from that pic, but is that a door that opens between the doorway and the PIR? If so, that could be a problem.
It's above the door but I guess that could still be a problem? Is there a different sensor that would work better, microwave?


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PIR pet detection (or false alarm) sensitivity depends on how high do the pet jumps of climp, but also on size, energy and hair. Their long hair hides the heat of their body. So, for this reason my persian cat is not detected by my Visonics Pet inmune PIR that points to the stairs where she spents half of her time.
If no false alarms are your goal and there are pets involved, use pet immune detectors and multiply X 2. Put them on a cross zone and you will never have a false alarm. This is rarely done because it costs twice as much but it works.