Motion Detector Placement/Type


Active Member

I am currently constructing my security/pre-wire schematic. However, I am having trouble with Motion Detector placement. Basically, I have no idea what type to get, or where to place them.

1) What type should I consider? Ceiling mount, infrared, curtain, hawkeye??

2) What are the best spots to place them versus concealing them at the same time?

If you guys would like to see a first floor plan, I can upload that.

Thanks guys!
Some things to think about during planning might include:

Passive IR devices are more sensitive to motion across their field of view than they are to motion towards or away from them.

Colder temps can cause unexpected behaviour (even indoors). Coming in from outside you might not be warm enough to trip the sensor as quickly as you would when your surface temperature is warm. Also if the room is kind of cool the sensor may pick up reflected IR around corners if there is something for it to bounce off like a mirror or a door with high gloss paint.

Direct sunlight through a window can also be a problem.
upstatemike said:
Direct sunlight through a window can also be a problem.
I can second this remark. I have to make sure one blind is closed during the day because the sun comes right in the window. Then when a cloud passes by it trips the motion sensor.

Another funny story. I had a motion sensor trip in the family room (in away mode). Turns out my son left a very large mylar balloon in the middle of the floor (elevated on a string as it was helium filled). When the AC turned on it moved the balloon back and forth (air going through ceiling's vents), which because I guess of the large mylar, changed the heat pattern in the room and tripped the sensor.
I agree with their comments although I haven't had any issues with sunlight tripping my sensors.

I recommend pointing them at the "choke-points"... anywhere people have to walk to get through a room. Also, I like to put them in corners if possible.

I use mine for security (when we're not home) and automation (when we are).

I use Optex Combination detectors. I pay a little more, but they work very well.
I am looking for sensors that are good. There is so much out there. Need something that integrates with ELK and is wireless. Also, don't want to break the bank.

I would want to do this more for occupancy as well as security.

Suggestions please with model numbers. thanks.

Well, for wireless to integrate to elk, and be robust for security, and supervised, there is really only 1 choice - Caddx Wireless. If you can tho, wired motions are a lot less expensive.
Steve said:
If you can tho, wired motions are a lot less expensive.
And the selection is huge. You can buy the specific sensor for each of your needs. In addition to PIR you get external sensors, dual PIR/Microwave, IR beams, pressure sensors, etc.
1) What type should I consider? Ceiling mount, infrared, curtain, hawkeye??
Ceiling mount - Good, un-obtrusive, slight hit on sensitivity, not much of a selection.
Infrared - Almost all of them are.
Curtain - describes a sensitivity pattern, ie think of walking through a curtain.
Hawkeye - Ack! Hang some garlic to ward off evil spirits.

If you haven't already, take a gander at BSR's excellent how-to on wiring an alarm. Also, take a look at the glossary (motion detectors and PIR IIRC) for more information on the various types of detectors.

I personally have Sentrol 5225 units mounted in the ceiling and like them. Another favorite is the SPY series from Visonic. Mounts in the wall or ceiling and the visible part is around the size of a quarter.

Just checking on some motion sensors to incorporate into my elk setup. I am interested in the dual technology but the better ones have pet immunity.

I have a 10 year old, 7 year old so would want to know where they are to monitor OCCUPANCY when at home. The little guy is not over 80 pounds.

Please provide suggestions of what you are using and what would work best for me.

I have 3 very large rooms that I want to monitor. 30feet by 14 feet.
The rest of the rooms are 11*13

Looking forward to hearing for you all of you.


P.S. false alarms will not go well with the head office (wife)

I expect your children (even at less than 80lbs) will still trip the "pet immune" sensors. The pet immunity assumes that pets are walking on 4 legs, so you're childrens height will still allow them to trip the PIRs even if they are below the weight requirements.

I'm sure there are others here with more exptertise in this area that may have more information...

The angle of installation impacts the pet inmunity. If you install them flat with the wall, it has greatest inmunity, but inclining it down by 15 or 20 degrees reduces the pet inmunity.

I got a dual sensor that have not installed yet. According to the documentatin, in addition to the inclination, other factors are height (pets moving on top of furniture), amount of fur (long hair pets vs. short hair pets). Notice that the long hair hides the heat of the pet.

In summary, this 80lbs inmunity is under best conditions - so most probably your childs will be detected unless they are crawling and wearing a coat.

I plan to use my sensor to detect presence too.