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Buried cable installation
Page 58
FiberPatrol FP1150 Product Guide
Intrusion detection (tunneling activity)
For detection of tunneling activity the recommended installation places the fiber optic sensor cable
a minimum of 2 m (6.5 ft.) below the ground’s surface. The increased burial depth is required to
prevent incidental vibrations originating above ground from causing nuisance alarms. FiberPatrol
can detect digging and tunneling activity up to 20 m (66 ft.) away from the sensor cable.
FiberPatrol can also detect the movement of people and vehicles inside an existing tunnel. The
burial depth of the sensor cable should be increased (made deeper) if there is the potential for a
tunnel that is more than 20 m deep. The maximum length for tunnel detection is 40 km/side (80 km
total).
Installation details
The following recommendations and requirements apply to FiberPatrol buried sensor applications.
•
burial depth (third party interference): the recommended burial depth for the sensor cable is
30 cm (1 ft.) ± 7.5 cm (3 in.) above the pipeline (see
Figure 64:
)
•
burial depth (above ground intrusion detection): the recommended burial depth for the sensor
cable is from 15 to 70 cm (6 to 28 in.) (see
Figure 65:
)
•
burial depth (tunneling activity): the recommended burial depth for the sensor cable is a
minimum 2 m (6.5 ft.) (see
Figure 66:
)
•
recommended clearance: minimum 6 m (20 ft.) of clearance on each side of the sensor cable
to prevent vibrations created by an object from disturbing the cable; total clear area centered
over cable 12 m (40 ft.) (see
Figure 67:
) (e.g., fences, sign posts, utility poles, trees, bushes
and vegetation over 30 cm high, etc.)
Figure 66: Sensor cable burial for tunneling detection
Note
Consult the local regulations and the pipeline specification for any
installation requirements concerning the location of buried cable for
communication and detection purposes.
Note
The maximum length for sensor 1 or sensor 2 is equal to the total length
specification of the particular model. This includes both lead cable in excess
of 500 m and detecting sensor cable. You cannot increase the length of one
of the sensors beyond the maximum by reducing the length of the other
sensor; e.g., the maximum length of each sensor in the FP115040 model is
40 km (50 km for TPI) the maximum combined length of both sensors is
80 km (100 km for TPI).
2 m (6.5 ft.)
sensor cable
ground surface
20 m (66 ft.)
tunnel