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GeoZone 'A' Perimeter Security System
Installation Manual
4 General Installation Methods
4.1 Fence Sensor Placement
The fence fabric is normally fixed on the outside of the fence post away from the
protected area. For fence posts with cranked tops, the crank is designed to face
towards the outside of the site, although in some cases it will be found that the reverse
is the case.
Install the sensor to the inner face of the fence fabric which offers slightly greater
protection against casual vandalism. The sensor must be looped around the inner side
of each fence post and not pulled between the post and the fabric.
If the fence fabric is on the inside face of the posts, the sensor can be installed on the
flat face of the fence. However, it should be noted that in this configuration climb over
detection is virtually impossible as the posts provide additional insulation from fence
fabric contact.
The optimum height for mounting the sensor is 1.0 m above ground level. This offset
towards the lower half of the fence provides better detection of cut through intrusion,
which is more likely to occur on the lower areas of the fence. See Figure 5.
Figure 5
4.2 Fence Posts
When the sensor passes around a fence post, it is necessary to leave sufficient slack
so that normal movement of the fence fabric does not cause the sensor to chafe
against the edges of the post. This is particularly important with concrete posts. It is
equally important not to leave excessive slack which can be shaken by strong winds
and cause false alarms. Figure 6 shows recommended spacing between the cable tie
nearest the post and the edge of the post for both concrete and metal posts. For
concrete posts, typically 90 mm x 100 mm in cross-section, dimension 'A' should be not
less than 100 mm. For metal posts, typically 50 mm x 50 mm in cross-section,
dimension 'B' should be not less than 75 mm. It is important to allow the sensor to form
a smooth curve as it passes round the inside of the fence post.
Page 8
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