Cable Specifications
Installation Handbook, Autroprime Interactive Fire Detection System, 116-P-APRIME2-INSTAL/DGB, Rev. C, 2016-29-02,
Autronica Fire and Security AS
Page 20
8.2.4 Panel Bus and Serial Port
Panel Bus
Capacitance pr. 1km cable
Capacitance < 200 nF
Capacitance < 100 nF
Maximum cable segment length
< 600 m
< 1000 m Cat 5 or better
Cable shall be twisted pair, characteristic
impedance 100 ohm.
Panel Bus
Power supply
2-wire 24V supply:
Calculation vs power loss
The power loss in these cables has to take into consideration the maximum current at
startup due to the Lamp test, which is 300 mA. Cable loss shall be limited to ensure at
least 18V supply to each panel in this situation.
RS 232
For cabinet internal connections only, limited to 10m.
For USCG installations the length is limited to 6m (20 feet).
RS485/422
Shielded cable is required if cable is >3m. Cable shall be twisted pair, 100 ohm
characteristic impedance (Cat 5 cable recommended).
Maximum length 1000 meters.
For USCG installations the length is limited to 6m (20 feet).
8.3 Detection Loop Cables
The maximum cable length is determined by both cable loss and
the at-site designed power consumption. Increasing current implies
a demand for less cable loss, hence increased copper area or
reduced cable length.
Note: The current consumption of LED indicators (on detectors or loop
units) in the event of an alarm has to be included.
The current consumption of other loads has to be included (for
example, loads applied to the output connection of detectors).
Units with varying current consumption, like sounders or strobe
devices have to be included according to the configured setting, for
example, the sound level may vary.
A 25% margin should be added for safety, to ensure correct operation
in case of excessive current consumption, degraded connections
(ageing), etc.
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