- Jan 19, 2019
- Reaction score
I can answer that very easily. If there was an alarm system it probably was for the door as a set of door contacts only. They circumvented that by the glass breakage on the door. They did not open the door, therefore did not break the contacts. If there was a motion detector, it was not tripped because the area it is protecting was not violated. The glass breakages can sometimes be detected by an electronic glass break sensor. These sensors, ever since their invention, have been very buggy and are prone to both false alarms and nondetection of glass breakage. They have replaced the labor intensive foil tape seen on old alarm system windows and doors.Can I inquire as to why they didn’t have an alarm? Seems like that would have prevented the follow theft at the very least.
Or, did they have an alarm. Maybe they did, and it just took LE 4 hours to respond. IDK, that’s why I’m asking.
Tempered glass is required by building code for doors because it shatters into small safe pieces. It also makes a completely different frequency from plate glass. Curtains, posters, stickers, blinds, and the like also change the glass break frequency and can muffle the sound. The detector manufacturers have been battling those problems ever since the technology came out. They even make glass break detection tools that make the sound of breaking glass, both tempered and plate. Each manufacturer of these detectors have instructions about where and how far away the devices have to be to test the detector's installation. In the 2000's window bugs were invented but still have trouble detecting broken glass and after years, sometimes lose their adhesive and fall off or come loose from the window reducing their effectiveness.
Having said all that, the installers I know and have watched never follow the instructions and a standard practice is throwing a set of keys at the detector or just tapping it to see if it trips. Usually, because the devices to test cost money and the companies don't want time wasted on testing especially if it won't test 100% which sadly is about 70 to 80% of all glass break installations.
False alarms have been reduced over the years by better technologies and installation practices, but environmental and user error ie. curtains, blinds, stickers, etc are still the bane of alarm companies