156 zones, some with timed entry / exit for cleaners, other zones with keyed isolation that security guards could used to go on their rounds. Main points have a local and remote audible ping, warning of entry into a resticted area, with a delay of 20 seconds before a full alarm is generated. Other areas used when and if needed, and are controlled from the security office, and anyone using those areas has to present a token to the entry door, which then tells the security office that the person has arrived at the point they should be at and nowhere else.
Then a painter knocks the cover off a dual-tech PIR and all hell breaks loose on the tamper system, which was also zoned because of the size of the system, I'm glad to say, but it shows you that a tamper is needed on any system, no matter how big or small. It's there for a really good reason.
With only a local panel sounder, the painter hears nothing, by the time a security guard gets to the area, the painter has picked up the cover and replaced it with no one knowing. The job of finding the fault is made much more difficult by the fact that, the faulty detector is now diguised by the painter replacing the front cover. But, due to the tamper circuit doing its job properly, the painter got such a fright and left everything alone where it fell, and the job of finding the faulty detector is made really easy because the young painter is spinning around in shock in the noisy corridor saying "sorry" every couple of seconds.
With a high security system like this one, the slightest thing out of place could cost millions to put right, so, although we are insured as a company, it is better to get it right on something as important as this.
Boy !!! Those were the days. :-))