12
The SPS and RPS provide three outputs for reverse-polarity notification appliance circuits.
This section describes basic NAC wiring from the SPS and RPS to 4100-compatible appliances.
The SPS and RPS supports both Class A and Class B NAC wiring.
Class A wiring allows appliances to communicate with the SPS or RPS even in the event of an open
circuit somewhere in the loop. Class A wiring requires that two wires are routed from the
SPS/RPS to each appliance, and then back again to the SPS or RPS.
The table below lists the maximum distances from the SPS or RPS to the last appliance in a
Class A configuration, depending on wire gauge and current. Use this table to calculate wire
distances for your application if you are using Class A wiring.
Table 5. Class A Wiring Distances
Alarm Current
@ 24 V
Max Distance
w/ 18 AWG
(0.8231 mm
2
)
Max Distance
w/ 16 AWG
(1.309 mm
2
)
Max Distance
w/ 14 AWG
(2.081 mm
2
)
Max Distance
w/ 12 AWG
(3.309 mm
2
)
DC
Resistance
0.25 A 420 ft. (128 m) 667 ft. (203 m) 1,063 ft. (324 m) 1,691 ft. (515 m) 6 Ohms
0.50 A 210 ft. (64 m) 334 ft. (102 m) 532 ft. (162 m) 845 ft. (258 m) 3 Ohms
0.75 A 140 ft. (43 m) 222 ft. (68 m) 354 ft. (108 m) 564 ft. (172 m) 2 Ohms
1 A 105 ft. (32 m) 167 ft. (51 m) 266 ft. (81 m) 423 ft. (129 m) 1.5 Ohms
1.25 A 84 ft. (26 m) 133 ft. (41 m) 213 ft. (65 m) 338 ft. (103 m) 1.2 Ohms
1.50 A 70 ft. (21 m) 111 ft. (34 m) 177 ft. (54 m) 282 ft. (86 m) 1 Ohm
1.75 A 60 ft. (18 m) 95 ft. (29 m) 152 ft. (46 m) 242 ft. (74 m) 0.86 Ohm
2 A 53 ft. (16 m) 83 ft. (25 m) 133 ft. (41 m) 211 ft. (64 m) 0.75 Ohm
2.25 A 47 ft. (14 m) 74 ft. (23 m) 118 ft. (36 m) 188 ft. (57 m) 0.67 Ohm
2.50 A 42 ft. (13 m) 67 ft. (20 m) 106 ft. (32 m) 169 ft. (51 m) 0.60 Ohm
2.75 A 38 ft. (12 m) 61 ft. (19 m) 97 ft. (30 m) 154 ft. (47 m) 0.55 Ohm
3 A 35 ft. (11 m) 56 ft. (17 m) 89 ft. (27 m) 141 ft. (43 m) 0.50 Ohm
Notes:
Max Distance = distance from SPS/RPS to last appliance.
This table is calculated at 50 degrees Centigrade (120 degrees Fahrenheit). If you are
installing in locations that could be exposed to higher temperatures, refer to National
Electrical Code (NEC) Table 8.
Distances are based on a 3V drop and take into account the worst-case panel output voltage.
If Circuit Integrity (CI) cable is used instead of housing cable in a fire rated enclosure,
reduce wiring distances by 38 feet (12 m) for every 10 feet (3 m) of potential fire exposure.
The direct exposure of the CI cable to flames increases the resistance of the cable.
Therefore, you must reduce the cable distance to account for the potential exposure of the
CI cable to fire.
If Wheelock appliances employing EZ Mount SNAP bases are used, reduce the wiring
distance and wiring resistance by:
12 gauge wire: 3.5 feet per appliance, 0.0125 Ohms per appliance
14 gauge wire: 2.2 feet per appliance, 0.0125 Ohms per appliance
16 gauge wire: 1.4 feet per appliance, 0.0125 Ohms per appliance
18 gauge wire: 0.9 feet per appliance, 0.0125 Ohms per appliance
Continued on next page
NAC Field Wiring
Overview
NAC Wiring Styles
Class A NAC
Wiring Table
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