8 Doc. 20780_03
Planning and Commissioning Manual ADPRO Passive-Infrared (PIR) PRO Series by Xtralis
Grade 2: Low to Medium Risk
An intruder or robber has little admitted knowledge of the security system; he has
generally available tools and portable instruments such as a multimeter.
Grade 3: Medium to High Risk
An intruder or robber has admitted that he is familiar with security systems, and has
an extensive inventory of tools and portable electronic devices.
Grade 4: High Risk
This level is used when security takes priority over all other factors. An intruder or
robber has admitted having the ability to plan a burglary or robbery in detail, and has a
complete kit including the means of substituting one component of a security system
for another.
NOTE!
In these levels, the word ‘intruder’ is used to include all types of threat,
such as robbery or the threat of physical violence, which could affect
the planning of a security system.
5. Types of attack on a perimeter security system
Walking, running or jumping:
An intruder tries to cross a boundary by walking or running. This usually occurs in
case of systems where there is no barrier or fence.
Climbing:
An intruder tries to get over the system by climbing directly over it. This applies only to
systems with barriers. The areas under surveillance of these systems cannot be
climbed into without assistance. A deferred detection system ‘assumes’ that an
intruder has entered by climbing, but entry might have been effected by cutting.
Cutting:
As with climbing, a barrier is required for this occurrence to be recognised. The
explanation is similar to ‘climbing’. Because of technology, PIR detectors cannot
detect cutting of the perimeter. However, the system can be planned so that
manipulation of fences, and above all subsequent penetration, can be securely
detected. The right choice of detector output is particularly important here.
Ladders:
‘Ladders’ is used here to mean all aids to elevation (such as a tall lorry parked near a
barrier). Two ways of surmounting a barrier with a ladder are to be distinguished:
- Use of a ladder that makes contact with a barrier (leaning ladders)
- Use of a ladder that makes no contact (a stepladder)
Because of technology, the PIR detector cannot detect the actual surmounting of a
barrier. Nevertheless, a system can be planned so that this type of attack and
subsequent invasions can be safely detected, provided the right detector has been
chosen. Again, careful planning of the system has a significant effect on the detection
of events and the false alarm rate. In contrast to other detection technologies, both
leaning ladders and stepladders are well known as aids to elevation.
Tunneling underground:
It is generally assumed that tunnelling under a barrier can in principle only be detected
by a ground detection system, because these are the only systems installed directly
into the ground. Because of technology, the PIR detector cannot detect tunnelling
under a barrier. But since the intruder has to come up to the surface to accomplish his
purpose, the system can be planned so that this type of attack, and subsequent
passage through the monitored area, can be safely detected. Here, too, the right
choice of detector is particularly important.
Driving through:
This is comparable to walking or running, but it involves greater speed and greater
mass. Because of this higher energy, in contrast to walking or running, a barrier can
be broken down. In some cases, because of technology the PIR detector cannot
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