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Installation
In general, the wire length is limited by resistance, but for heavier wire gauges, capacitance is the limiting factor. Maximum length can
never be more than 6,000 feet (1,800 m), regardless of gauge used. The following formulas are used to generate the wire distances:
Maximum Resistance (Ohms)
Maximum Wire Length (feet)
(6,000 feet maximum)
Exception: When using the N-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:
Wiring Distance Calculation Example:
Suppose a system is configured with the following ANN-BUS modules:
•
3 N-ANN-80 Remote Fire Annunciators
•
1 N-ANN-S/PG Serial/Parallel Printer Interface Module
The total worst case current is calculated as follows:
N-ANN-80 Current Draw
N-ANN-S/PG Current Draw
Total Worst Case Current Draw
Wiring Configuration
Figure 2.17 illustrates the wiring between the FACP's Primary ANN-BUS and ANN-BUS devices.
32
=
=
where: Rpu = Ohms per 1,000 feet for various Wire Gauges (see table below)
Wire Gauge
22
18
16
14
Wire Gauge
18
16
14
12
TB1
4 3 2 1
ANN-BUS Device
Figure 2.17 Primary ANN-BUS wiring to ANN-BUS Device
2.0 Volts
Total Worst Case Current Draw (amps)
Maximum Resistance (Ohms)
Rpu
Ohms per 1,000 feet (Rpu)
16.2
6.4
4.02
2.54
Maximum Wire Length
312 feet
497 feet
787 feet
1,250 feet
= 3 X 0.040 amps
= 1 X.0.040 amps
ANN-BUS and power wiring are
supervised and power-limited
Primary
+
ANN-BUS
NFW-50X
NFW-50X Manual — P/N LS10129-001NF-E:C 7/25/2018
Optional Module Installation
x 500
= 0.120 amps
= 0.040 amps
= 0.160 amps
-
24 VDC
nonresettable
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