FWL_Engineer said:
In these situation we have mounted smaller PIR's in the window recess looking down from the top..open the window and bammm, off goes the alarm.
That is all very well until.................
some one leaves the window open / a jar
the cat jumps up onto the window sill (inside)
what if the intruder comes in from other end of room, that pir is going to do a lot of good then isn't it?
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You should programme pirs so that in "night set" the first pir to see someone (downstairs hall perhaps, as if any upstairs they should be off) will start the entry timer (to enable person to switch alarm off)
unlike a fire alarm, bs 4737 says that each volumetric detector should be on its own circuit (i never said you didn't)
for those that do not know>
volumetric detectors are used as trap protection, yes that does mean that they do not go off untill intruder is in, but that then means the person has commited an offence by trespassing on your property, vibration sensors as you call them, can be set off (and quite often are, especially when set too sensative) by window cleaner putting ladder on window, bird hitting window, tree branch hitting window (it has happened, yes it is owners fault for letting tree grow too much , but it happens)
Police will not respond to an alarm unless it has a URN (unique reference number) this has to be applied for at time of installation, if you have 2 false alarms in a rolling 12 months you will receive a warning letter.
if you have 4 false alarms in a rolling 12 months your URN will be withdrawn. (this is not re issued until your alarm company updates the system, to the new BS , this did not used to be the case)
the new regulations state that an intruder alarm (new installations) must have confirmed signalling,
That is for example a contact on the door and a pir covering the general area near the door, intruder forces door, (ARC* receive intruder signal, but do not police it) pir is then set off, alarm sends confirmed signal to ARC*, this is then policed as intruders on site.
also new installations nust have "a means of turning alarm off on entry other than enterting the code" this is usually over come by the use of a "proximity reader" to which the owner holds a "tag"
you also have not mentioned such things as Personal attack buttons, active infra red beams, but the list goes on, and on (so we wont go there any more)
*ARC is Alarm Receiving Centre, this is where the alarm signal is sent to, and is covered by its own set of BS standards. The ARC is in effect a filtering place as to if a call gets policed or not, some well known stores have their own ARC (as opposed to the alarm companies ARC) and they also monitor for example the freezers, yes the freezers, freezers get too warm thats a lot of "stock" they stand to loose.
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You may also be interested (or not) to know the following.
you know those "tardis toilets" the modern looking ones that have a sliding door that opens when you put in your money (if required) then press the button and door opens you go in do your thing, come out and it washes it all. well they are connected to an ARC (its true) to say for example it has run out of toilet paper or soap.