Motion sensors are great additions for a complete alarm security system. They can be used as a backup for window protection or they be the primary equipment for protecting break ins through windows or other types of burglary of habitat.

Motion detectors can be wireless or hard wired into your alarm’s control panel. They are usually installed indoors in a large area such as a living room, dining room, or even a hallway. The idea is for it to detect motion when someone comes inside its coverage area. Inside the motion detector there is a beam of infrared light . When somebody walks between the light source and the sensor, the path of the beam is blocked briefly. The sensor registers a drop in light levels and sends a signal to your alarm panel (or your control box as some might call it).
There are some more sophisticated motion detectors out there , commonly used on a commercial level where it can “see” the infrared energy emitted by an intruder’s body heat. When an intruder walks into the field of view of the detector, the sensor detects a sharp increase in infrared energy. Of course, there will always be gradual fluctuation of heat energy in an area, so PIR detectors are designed to trigger the alarm only when there is a vast difference in heat signature coming off the body.
All these motion detector designs can be combined in a house to offer complete coverage. In a typical security system, the control box will not sound the alarm immediately when the motion detectors are triggered. There is a short delay to give the homeowner time to enter a security code that turns the system off. Almost every modern alarm system will allow you to arm your home with the motion sensors OFF (such as when people are inside sleeping at night).

Pet immunity motion sensors mean they are tuned to detect a motion on a certain weight limit. There are 40lb weight limit motion sensors (most common) and then there are 80lb and the highest I believe is 100lb. You don’t want to have a motion sensors with a pet immunity of more than 100lbs. It might not be effective . If you own a pet that is pushing close to 80lbs, and they are indeed in your home free to roam while you are gone, then I would treat the pet like a person and just arm your system for STAY mode. Or “doors and windows only” mode. Of course if your pet doesn’t stay inside the home while you are gone, it’s not a factor. Or maybe your large pets are confined to a room or a cage while you are gone. If that’s the case then no big deal. In my view (just for safety) I say pets can freely roam your home if they are under 20lbs without too much worry. If your pet is under 20lbs such as a small dog or a cat, then you really don’t have to worry too much about a motion sensor going off and causing false alarms. Anything over 20lbs (even though a motion sensor pet immunity limit is 40lbs/80/100) . heightens the chances of your motion sensor detecting them anyway. That is just my personal opinion.

Another Alternative.
If your pet is confined to a cage or room that is out of the motion sensor’s zone then you will be fine. If your pet is large or weighs 50lbs or over and you question whether it will be an issue for your motion detector, you can always treat the animal like a person. On your way out the door, you would set your alarm system to “STAY” ( as opposed to AWAY) . By pressing “STAY” or on some alarm panels its called “INSTANT” or INSIDE etc, the motion sensor is zoned out. In other words it’s by passed and will not be on. Only your doors will be armed and windows too if you have contacts on the windows. It would be the same type of action you would di if a person was left behind in the house. And let’s face it, if you have a really big dog in the house, he or she will be compensate the absence of a motion sensor as far as securing your home perimeter.

Another Alternative
If you think your pet is too large or 40lbs or more you can always (when in doubt) treat your animal like a person. On your way out the door you just simply arm your security system to “STAY” (as opposed to AWAY)… some keypads will say INSIDE or INSTANT etc…
This way your motion sensor will be zoned out…. as if someone is inside the home. Your door contacts will be armed and windows too if you have contacts installed on your windows. And lets face it, your large pet will probably compensate the absence of a motion detector as far as securing your home. If your pets are confined to a room or locked in a cage or pet container, a motion detector can be used so long as the pet is confined in an area that is not in the motion senor’s zone area.

If large pets are too much of a problem with motion sensors there are other avenues to protect intruders from breaking in through your windows. You may want to invest putting contact sensors on each and every window. I recommend glass break detectors that are designed to go off it hears the acoustic sound of glass shatter. Weight is not a factor on glass breaks. We’ll talk about glass break detectors in another blog.
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This BLOG is written by Jimmy Maddox, employed by America’s Ultimate Security. The opinions and advise are strictly his and do not necessarily reflect the opinions of the company, AUS Inc., ADT Security or any other company that may have been implied.