Calculating Wiring Distance For Ann-Bus Modules - Fire-Lite MS-9050UD Manual

ANN-BUS Devices

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 nec-
essary 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:
ANN-80(C) LCD Annunciator/Indicator
ANN-S/PG Serial/Parallel Printer Interface Module
ANN-I/O LED Driver Module
ANN-RLY Relay Module
ANN-(R)LED Annunciator Module
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 (*). Maxi-
mum 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.
Total Worst Case Current
Draw (amps)
0.100
0.200
0.300
0.400
0.500
The following formulas were used to generate the wire distance chart:
MS-9050 Series Manual — P/N 52413:F 10/22/2010
Model Number
1 Total worst case current draw on a single ANN-BUS cannot exceed 0.5 amp.
If current draw exceeds 0.5 amps, refer to "Powering ANN-BUS Devices from
Auxiliary Power Supply" on page 39.
Wiring Distance: ANN-BUS Modules to FACP
22 Gauge
1,852 ft.
926 ft.
617 ft.
463 ft.
370 ft.
Table 2.1 Wiring Distances
Maximum Resistance (Ohms)
Maximum Wire Length (feet)
(6,000 feet maximum)
where: Rpu = Ohms per 1,000 feet for various Wire Gauges (see table below)
Wire Gauge
22
Worst Case Current Draw
0.040 amps
0.040 amps
0.200 amps
0.075 amps
0.068 amps
18 Gauge 16 Gauge
4,688 ft. * 6,000 ft.
2,344 ft. 3,731 ft.
1,563 ft. 2,488 ft.
1,172 ft. 1,866 ft.
938 ft. 1,493 ft.
6.0 Volts
=
Total Worst Case Current Draw (amps)
Maximum Resistance (Ohms)
=
Rpu
Ohms per 1,000 feet (Rpu)
16.2
Installation
1
14 Gauge
*6,000 ft.
5,906 ft.
3,937 ft.
2,953 ft.
2,362 ft.
*500
37