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GeoZone 'A' Perimeter Security System
Installation Manual
4.5 Ground Level Variation
It will often be found that, because of variations in ground level, the fence panels may
be stepped up or down at support posts to eliminate gaps below the fence, or the need
to trench out high spots between the posts. When this happens, it is necessary to allow
the sensor to follow the steps to maintain the correct average height above the ground
level.
Figure 8 shows the line of the sensor following the ground contours using smooth
bends in the sensor at each step.
Figure 8
4.6 Non-Sensitive Sections
In many cases, there will be areas within a sensor zone where, for various reasons, it is
not necessary or desirable to provide active sensor coverage.
For instance, if a zone is split by a building or other obstruction, a section of dead cable
can be inserted in the zone at this point to be re-connected to the sensor at the other
side of the obstruction. Another application of dead cable would be to provide an
interconnection between sensor on a fence zone and an analyser mounted remotely
from the fence, perhaps in a building or other protected area.
The correct dead cable is available from Geoquip Worldwide, part number GQFC-9.
This cable comprises an overall drain wire and a twisted pairs of wires with a foil
screen. The cable has a tough black polythene outer sheath making it weather
resistant and fully suitable for outdoor use. This cable is not suitable for direct burial.
The junction between the sensor and the dead cable is made within a weather-proof
GQCOMBO junction box. This junction box provides an integral tamper switch to force
a sensor tamper condition if the lid is removed; see figure 9.
Provided that the cables are terminated correctly and moisture is excluded from the
joint, almost any number of such sections can be inserted in a zone.
Page 10
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