13
The table below lists the maximum distances from the SPS or RPS to the last appliance in a
Class B configuration, depending on wire gauge and current. Use this table to calculate wire
distances for your application if you are using Class B wiring.
Table 6. Class B 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 840 ft. (256 m) 1,335 ft. (407 m) 2,126 ft. (648 m) 3,382 ft. (1,031 m) 12 Ohms
0.50 A 420 ft. (128 m) 667 ft. (203 m) 1,063 ft. (324 m) 1,691 ft. (515 m) 6 Ohms
0.75 A 280 ft. (85 m) 445 ft. (136 m) 709 ft. (216 m) 1,127 ft. (344 m) 4 Ohms
1 A 210 ft. (64 m) 334 ft. (102 m) 532 ft. (162 m) 845 ft. (258 m) 3 Ohms
1.25 A 168 ft. (51 m) 267 ft. (81 m) 425 ft. (130 m) 676 ft. (206 m) 2.4 Ohms
1.50 A 140 ft. (43 m) 222 ft. (68 m) 354 ft. (108 m) 564 ft. (172 m) 2 Ohms
1.75 A 120 ft. (37 m) 191 ft. (58 m) 304 ft. (93 m) 483 ft. (147 m) 1.71 Ohms
2 A 105 ft. (32 m) 167 ft. (51 m) 266 ft. (81 m) 423 ft. (129 m) 1.5 Ohms
2.25 A 93 ft. (28 m) 148 ft. (45 m) 236 ft. (72 m) 376 ft. (115 m) 1.33 Ohms
2.50 A 84 ft. (26 m) 133 ft. (41 m) 213 ft. (65 m) 338 ft. (103 m) 1.2 Ohms
2.75 A 76 ft. (23 m) 121 ft. (37 m) 193 ft. (59 m) 307 ft. (94 m) 1.09 Ohms
3 A 70 ft. (21 m) 111 ft. (34 m) 177 ft. (54 m) 282 ft. (86 m) 1 Ohm
Notes:
Max Distance = distance from SPS or 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 NEC Table 8.
Distances are based on a 3 V 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.
Continued on next page
NAC Field Wiring,
Continued
Class B NAC
Wiring Table
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