My schools burglar alarm system

Security System Media
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My school has a ADT/BOSCH burglar alarm system, there is PIRs though that arent a part of the system, as there is old ones that were disconnected and are just there forever guarding the areas they were placed in, and Kantek REX (Request to exit) sensors above every doorway INSIDE the building that have keycard scanners, i have seen them everywhere and they are placed on the other side of the locked doors and when they detect a person under them, they activate making a loud click, and unlock the door for a short amount of time, At first i thought they were a part of the burglar alarm system for a long time but a looked them up and found out what they are for
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The vintage, disconnected sensors sort of look like this one but with no power and no panel to be hooked up to
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Now onto the working burglar alarm part my school has a combination of a older ADT panel, and BOSCH PIRs and Ademco sirens, and one PIR located in the library is one of the fancy Tritech motion detectors with both motion and infrared
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I think the first motion sensor is for a mag lock.

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One weird thing is that both my elementary school and middle school had almost those exact same things at every door that had access control. The weird part is that they used strike plate locks and not mag-locks and had mechanical egress that did not relate to the access control. I know they are active because they were installed only around 10-15 years ago and have a led that changes from red to green when they detect motion. They also have a relay that clicks when the light turns green but they don’t appear to actually control anything.