ZP3 Fire Control Panel Installation, Commissioning and Maintenance Manual
Page 110
REV 11 (ISS 08/03/2010)
Rules for RS485 cabling
1. Cable requires 2 conductors plus a shield. The cable is terminated at each end to a 9-pin "D"
connector, or onto terminals, depending upon the equipment.
2. The shield must be insulated, and connected only at the points shown on the system
installation drawing. If the shield is not insulated, and could be earthed, then a 3-conductor
cable is required. The third wire serves the function of the screen.
3. Only cable specifically manufactured for RS485 should be used. This is an ultra low
capacitance cable with capacitance of 0.04 µf/1000 metres.
4. The conductor size, when using shielded cable with a capacitance of 0.04 µf/1000 metres,
should be as follows:
0.25 mm
2
- up to 1000 metres
0.5 mm
2
- 1000 to 2000 metres
5. No cables or conductors for other services must be run inside the same shielding.
6. The maximum communication distance for RS485 cabling is 2000 metres. If greater distances
are required, please contact Ziton.
7. Where wiring connects to several panels or devices, it must be daisy-chained from point to
point, (not connected in a star pattern).
DC Control lines
General
ZP systems operate on 24 VDC. The majority of field wiring consists of power supply wiring, for
devices that require 24 V, or switched low voltage DC circuits. These are used for functions such
as audible alarm sounders, mimic panels, magnetic door holders, CO
2
, water mist or Halon
extinguishing systems, and control of building systems such as evacuation systems, air-
conditioning, dampers, and lifts and elevators.
Wiring specifications depend entirely on the current consumption of the devices connected, the
number of devices on the same line, and the distance of each device from the control unit.
DC Cable type
Any type of cable may be used for dc control circuits. Normally, PVC insulated, single or multicore
cable is used. It is not necessary to shield these cables.
DC Cable size
See Table 28. Conductor diameters of 0.5 mm
2
to 2.5 mm
2
may be used. Cables should be sized
so that a maximum volt drop of 1.0 V occurs at the furthest device when the circuit is operated at
maximum power consumption.
Table 28: DC Cable Size
Length of 2-core Cable giving a 1 V drop (Metres)
Device Current Consumption
Cable Size (mm²)
50 mA
100 mA
250 mA
500 mA
1 A
0.5
250 125 50 -
-
0.75
375 180 75 -
-
1.0
500 250 100 50 -
1.5
750 375 150 75 35
2.5
1250 625 250 125 60
