Wiring Distance Calculation Example - Honeywell Farenhyt RPS-1000HV Manual

Before You Begin Installing
ECS-VCM / ECS-VCM with ECS-SW24
ECS-LOC with ECS-SW24
ECS-NVCM Network Voice Control Module
ECS-EMG keypad
SK-NIC Network Interface Card
CELL-MOD/CELL-CAB-SK
SK-F485C Fiber Converter
1
After calculating the total worst case current draw, Table 2.7 specifies the maximum distance the modules can be located from the panel on a
single wire run. The table insures 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, regardless of gauge used. (The
formula used to generate this chart is shown in the chart below).
Total Worst Case
Current Draw (amps)
0.100
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000 (Max)
The following formulas were used to generate the wire distance chart

Wiring Distance Calculation Example

Suppose a system is configured with the following SBUS modules:
2 - RA-1000 Fire Annunciators
1 - RPS-1000 Intelligent Power Expander
1 - 5865 LED Fire Annunciator
1 - 5824 Parallel/Serial Interface
24
Model Number
1
All devices must use the same SBUS and VBUS.
Wiring Distance: SBUS Modules to Panel
22 Gauge
1852 ft.
926 ft.
617 ft.
463 ft.
370 ft.
309 ft.
265 ft.
231 ft.
206 ft.
185 ft.
Table 2.7 Wire Distances Per Wire Gauge
Maximum Resistance (Ohms) =
Maximum Wire Length (Feet) =
(6000 feet maximum)
where: Rpu = Ohms per 1000 feet for various Wire Gauges (see table below)
Wire Gauge
Table 2.8 Typical Wire Resistance Per 1000 ft.
1
0.115 amps per device/0.185 amps for last device
0.210 amps per device /0.325 amps for last device
18 Gauge
4688 ft.
2344 ft.
1563 ft.
1172 ft.
938 ft.
781 ft.
670 ft.
586 ft.
521 ft.
469 ft.
6.0 Volts
Total Worst Case Current Draw (amps)
Maximum Resistance (Ohms)
Rpu
Ohms per 1000 feet (Rpu)
22
18
16
14
Worst Case Current Draw
0.059 amps
0.06 amps
0.021 amps
0.145 amps
0.125 amps
16 Gauge
* 6000 ft.
3731 ft.
2488 ft.
1866 ft.
1493 ft.
1244 ft.
1066 ft.
933 ft.
829 ft.
746 ft.
* 500
16.2
6.4
4.02
2.54
RPS-1000 Manual — P/N 151153:R 2/15/2022
Wiring Specifications
14 Gauge
* 6000 ft.
5906 ft.
3937 ft.
2953 ft.
2362 ft.
1969 ft.
1687 ft.
1476 ft.
1312 ft.
1181 ft.