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SBUS Wiring
4.4 SBUS Wiring
This section contains information on calculating SBUS wire distances and the types of wiring configurations (Class B).
4.4.1 Procedure to Calculate the Wiring Distance for SBUS Modules
To determine the type of wire and the maximum wiring distance that you can use with the fire alarm control panel SBUS accessory mod-
ules, refer to the following instructions.
1.
To calculate the wire gauge that you must use to connect the SBUS modules to the fire alarm control panel, it is necessary to
calculate the total "worst case" current draw for all modules on a single 4-conductor bus.
2.
To calculate the total "worst case" current draw, add 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.
3.
After you calculate the total "worst case" current draw, refer to Table 4.4 to obtain the maximum distance the modules can be
located on a single wire run fromthe fire alarm control panel.
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, 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: T
he following formulas were used to generate the wire distance chart.
Maximum Resistance (Ohms) =
Maximum Wire Length (Feet) =
(6000 feet maximum)
where: Rpu = Ohms per 1000 feet for various wire gauges (see table below)
Wiring Distance Calculation Example:
For example, if your system is configured with the following SBUS modules:
•
2 - Module RA-1000 LCD Annunciator
•
1 - GFPS-6S NAC Expander
•
1 - 5824 Parallel/Serial Interface
You can calculate the total "worst case" current draw as follows:
SBUS Modules
RA-1000 Current Draw
GFPS-6S Current Draw
5824 Current Draw
Total "Worst Case" Current Draw
Note: Using this value, and referring to the Wiring Distance table, it can be found that the available options are:
- 370 feet maximum using 22 Gauge wire
- 938 feet maximum using 18 Gauge wire
- 1493 feet maximum using 16 Gauge wire
- 2362 feet maximum using 14 Gauge wire
GWF-7075 Addressable Fire Alarm Control Panel Manual — P/N LS10147-002GF-E:E 06/11/2019
Model Number
RA-1000 LCD Annunciator
5824 Serial/Parallel Printer Interface Module
5880 LED I/O Module
GFPS-6S NAC Expander
CELL-MOD, CELL-CAB-GWF
Table 4.1 Worst Case 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 Distrance
Wire Gauge
22
18
16
14
= 2 x .100 amps
= 1 x .010 amps
= 1 x .040 amps
Table 4.3 Wiring Distance Calculation Example
Worst Case Current Draw
.100 amps
.040 amps
.250 amps
.010 amps
.145 amps
18 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.
6.0 Volts
Total Worst Case Current Draw (amps)
Maximum Resistance (Ohms)
Rpu
Ohms per 1000 feet (Rpu)
16.2
6.4
4.02
2.54
Calculation
Control Panel Installation
16 Gauge
14 Gauge
* 6000 ft.
5906 ft.
3937 ft.
2953 ft.
2362 ft.
1969 ft.
1687 ft.
1476 ft.
1312 ft.
1181 ft.
* 500
Result
= .200 amps
= .010 amps
= .040 amps
= .250 amps
21
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