Why A Motion Detector Should Only Be Used As Backup
Motion detectors are a great addition to a burglar alarm system but they should only be used as backup. Think about this for a moment. A burglar alarm is supposed to detect when someone has broken through the perimeter and a motion detector is almost always located on the inside of the home. If the motion detector is what set off the system, then that means the burglar or the intruder is already inside your house. Not the picture of an ideal situation if you ask me.
Let me back up a bit and explain a little about what a motion detector is and the different types of motion detectors that are available. A motion detector is pretty much what it’s name implies. It detects motion when there is something that tells the detector there is movement within its field of view, it send a signal to the alarm system control panel.
When the burglar alarm control panel gets the signal it will do one of three things:
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Set off the alarm, if the alarm system is set in the “away” mode (meaning no one should be home and have the motion detector on) and someone or something sets off the motion detector the alarm system will sound immediately.
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Ignore it, if the alarm system is set in the “home” mode (meaning there is someone home and have the motion detector turned off) and someone or something sets off the motion detector the alarm system will ignore the signal.
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Delay a reaction, if the motion detector is located in the vicinity of the entry/exit door or the keypad, the motion detector should be in what is called a “follower” zone. Which means if the door is opened before the motion detector is activated, the alarm system will allow you enough time to turn off the system before going off.
There are 4 types of motion detectors used with burglar alarm systems.
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Passive infrared (PIR) – this is the most common and usually the least expensive. This motion detector looks for a change in temperature (like body heat). This motion detector can be set off when something like the sun shining in a window heats up the space.
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Microwave motion detector – this motion detector sends out microwave pulses and measures the reflection off of a moving object. Think of it like something that is throwing out bouncy balls and each ball takes a certain amount of time to return. When the ball comes back sooner than expected, it triggers an alarm. Milar balloons (you know the ones that say “Happy Birthday”) are found to be the cause of false alarms with this motion detector.
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Dual-technology motion detector – this motion detector uses a combination of passive infrared and microwave technologies. The benefit of using this type of motion detector with your alarm system is that false alarms are less likely to happen.
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Pet PIR/Motion detector – the final motion detector that I want to tell you about is the one that is designed to ignore pets that weigh up to 80 pounds. These motions are great for people with pets but they can trigger false alarms if your pet is a known jumper. Cats or dogs jumping up or down from a couch, bed, counter, whatever, can sometimes set off an alarm.
What all this means is that you realistically can only use your motion detector when you are NOT at home. Unless of course, when you are at home at night and you don’t every get up to go to the kitchen for a drink of water or a snack, the kids don’t use the bathroom, and they stay in their room until morning, then maybe you can use the motion detector when you are at home.
So with this in mind, you can see that having a motion detector on your burglar alarm system is great to use when you aren’t at home and an intruder does find a way to get inside your home without setting off any of the perimeter devices. You’ll be glad that you added the motion detector to your home security system then, but really it’s only a good thing as a backup detection device. Please don’t rely only on a motion detector to protect multiple openings. Use door and window contacts to protect all of your openings. You’ll be better protected.
