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5.6 OFFICIAL SYMBOL CONVENTIONS FOR ANTI-
INTRUSION SYSTEMS
5.7 SHIELDED CABLE CONDUCTOR RESISTANCE
TABLE
5.7.1 Input and signal connections
Control panel
Magnetic contact detector
Inertial vibration detector
Microphone glass break detector
Microphone detector
Passive infrared detector
Microwave detector
Control component with electronic key
Message dispatcher on dedicated line
Message dispatcher on switched line
Self-powered audible alarm device
Audible alarm device
Illuminating alarm device
SHIELDED
ALARM CABLE
FORMATION
CONDUCTOR
DIAMETER [mm]
MINIMUM
RESISTANCE
OHM PER 1
METRE
MINIMUM
RESISTANCE
OHM PER 100
METRES
n X 0.22 mm
2
0.50
0.085
8.5
n X 0.50 mm
2
0.80
0.032
3.2
n X 0.75 mm
2
0.90
0.026
2.6
n X 1 mm
2
1
0.020
2
n X 1.5 mm
2
1.28
0.013
1.3
n X 2.5 mm
2
1.65
0.008
0.82
For the bus signals (A and B) you can use a conductor with
section of 0.22 mm².
The resistance shown in the table refers to a single conductor,
so if, for example, you want to evaluate the additional resistance
introduced by the cable for a run of 100m, you need to double
the length. You therefore need to consider 200m total length of
conductor (100m outward to the point and 100m return from
the point).
In the case of a contact connected to the control panel by a
run of 100m of cable with “n” structure for 0.22 mm², the total
resistance added by the cable becomes 17 ohm. For connection
to an alarm input, 17 ohm does not generally compromise the
performance of the system.
