Comander Perimeter Security System
Engineering and Installation Manual
Page 51 of 72
5.2.9 Calculating Interceptor Cable Length
Most perimeter protection is divided into separate zones of between 50m and 200m.
However the actual length of sensor required to protect a certain length of perimeter
must be calculated carefully to allow for fence posts, corners, gates etc.
An extra allowance of 5% must be made for the fact that the sensor will be looped
around posts, 7m must be allowed for each corner, and for each single gate the extra
length of cable required is twice the sum of the width and height of the gate. A double
gate requires four times the sum of its width and height.
In order to calculate the actual length of sensor cable needed to cover a given length of
fence, therefore, the following formula should be used ...
A: Length of zone
B: Allowance for fence posts - add 5% of zone length
C: Allowance for corners - add 7m for each
D: Allowance for single gates - add 2 x (Width+Height) for each
E: Allowance for double gates - add 4 x (Width+Height) for each
Total: A + B + C + D + E
So for a single-run 200m zone of 2.5m high fence which includes two corners and one
5m wide gate, the calculation is as follows ...
A: Length of zone - 200m
B: Allowance for fence posts - add 5% of zone length: +10m
C: Allowance for corners - add 7m for each: +14m
D: Allowance for single gates - add 2 x ( 5 + 2.5 ) for each: +15m
E: Allowance for double gates: +0m
Total A + B + C + D + E = 239m
Details of how to deploy the cable around posts, corners and gates are given in the
following pages.
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