Sbus Wiring; 1: Calculating Wiring Distance For Sbus Modules - Honeywell 6808 Installation And Operation Manual

Control Panel Installation

4.4 SBUS Wiring

This section contains information on calculating SBUS wire distances and the types of wiring configurations (Class B).
4.4.1 Calculating Wiring distance for SBUS modules
The following instructions will guide you in determining the type of wire and the maximum wiring distance that can be used with control
panel SBUS accessory modules.
To calculate the wire gauge that must be used to connect SBUS modules to the control panel, 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 table below..
NOTE: Total worst case current draw on a single SBUS cannot exceed 1 amp
After calculating the total worst case current draw, Table 4.2 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 note 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)
NOTE: The following formulas wee used to generate the wire distance chart.

Wiring Distance calculation example:
Suppose a system is configured with the following SBUS modules:
2 - Module 5860
Remote LCD Annunciator
1 - 5496 NAC Expander
1 - 5865 LED Fire Annunciator
1 - 5824 Serial/Parallel Printer Interface Module
The total worst case current is calculated as follows:
30
Model Number
5860, 6855 or 6860 LCD Annunciator
5824 Serial/Parallel Printer Interface Module
5880 LED I/O Module
5865 LED Fire Annunciator
5496 NAC Expander
SK-NIC Network Interface Card
CELL-MOD/CELL-CAB-SK
SK-F485C Fiber Converter
Table 4.1 : SBUS Device Current Draw
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 4.2 : Wiring Distances Per Wire Gauge Using Copper Wire
Worst Case Current Draw
.100 amps
.040 amps
.250 amps
.200 amps
.010 amps
.021 amps
.145 amps
.125 amps
18 Gauge 16 Gauge
4688 ft. * 6000 ft.
2344 ft. 3731 ft.
1563 ft. 2488 ft.
1172 ft. 1866 ft.
938 ft. 1493 ft.
781 ft. 1244 ft.
670 ft. 1066 ft.
586 ft. 933 ft.
521 ft. 829 ft.
469 ft. 746 ft.
6808 Manual — P/N LS10146-001SK-E:C 09/28/2017
14 Gauge
* 6000 ft.
5906 ft.
3937 ft.
2953 ft.
2362 ft.
1969 ft.
1687 ft.
1476 ft.
1312 ft.
1181 ft.