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RP-2001 Series Manual —
P/N 52985:D5 1/26/2017
Installation
ANN-BUS Devices
2.7.1 ANN-BUS Wiring
This section contains information on calculating ANN-BUS wire distances and the types of wiring
configurations (Class B).
Calculating Wiring Distance for ANN-BUS Modules
The following instructions will guide the installer in determining the type of wire and the maximum
wiring distance that can be used with FACP ANN-BUS accessory modules.
To calculate the wire gauge that must be used to connect ANN-BUS modules to the FACP, it is
necessary to calculate the total worst case current draw for all modules on a single 4-conductor bus.
The total worst case current draw is calculated by adding the individual worst case currents for each
module. The individual worst case values are shown in the following table:
After calculating the total worst case current draw, Table 2.1 specifies the maximum distance the
modules can be located from the FACP on a single wire run. The table ensures 6.0 volts of line drop
maximum. In general, the wire length is limited by resistance, but for heavier wire gauges,
capacitance is the limiting factor.
These cases are marked in the chart with an asterisk (*). Maximum length can never be more than
6,000 feet (1,800 m), regardless of gauge used. The formula used to generate this chart is shown in
the note below.
Model Number
Worst Case Current Draw
1
1 Total worst case current draw on a single ANN-BUS cannot exceed 0.5 amp.
N-ANN-80(C) LCD Annunciator/Indicator
0.040 amps
N-ANN-S/PG Serial/Parallel Printer Interface Module
0.040 amps
N-ANN-I/O LED Driver Module
0.200 amps
N-ANN-LED Annunciator Module
0.068 amps
N-ANN-RLY Relay Module
0.075 amps
Wiring Distance: ANN-BUS Modules to FACP
1
Total Worst Case Current
Draw (amps)
22 Gauge
18 Gauge
16 Gauge
14 Gauge
0.100
1,852 ft.
4,688 ft.
* 6,000 ft.
*6,000 ft.
0.200
926 ft.
2,344 ft.
3,731 ft.
5,906 ft.
0.300
617 ft.
1,563 ft.
2,488 ft.
3,937 ft.
0.400
463 ft.
1,172 ft.
1,866 ft.
2,953 ft.
0.500
370 ft.
938 ft.
1,493 ft.
2,362 ft.
Table 2.1 Wiring Distances
1
The following formulas were used to generate the wire distance chart:
Maximum Resistance (Ohms)
=
6.0 Volts
Total Worst Case Current Draw (amps)
Maximum Wire Length (feet)
(6,000 feet maximum)
=
Maximum Resistance (Ohms)
*500
Rpu
where: Rpu = Ohms per 1,000 feet for various Wire Gauges (see table below)
