Honeywell MS-5UD Series Manual page 39

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.
Total Worst Case
Current Draw (amps)
0.100
0.200
0.300
0.400
0.500
Note: The following formulas were used to generate the wire distance chart:
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)
Exception: When using the ANN-RLY module, the installer must ensure that the maximum
24VDC power line drop does not exceed 0.3 volts. This results in the following wiring
limitations:
MS-5UD/MS-10UD Series PN 52626:B 8/01/2008
24 VDC Power 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
=
Total Worst Case Current Draw (amps)
= Maximum Resistance (Ohms)
Wire Gauge Ohms per 1,000 feet (Rpu)
22
18
16
14
Wire Gauge Maximum Wire Length
18
16
14
12
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
Rpu
16.2
6.4
4.02
2.54
312 feet
497 feet
787 feet
1,250 feet
Installation
14 Gauge
*6,000 ft.
5,906 ft.
3,937 ft.
2,953 ft.
2,362 ft.
*500
39