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5-7
Table 5-2 lists the maximum distances from the NAC terminal block to the last appliance
in a Class B (string) configuration, depending on wire gauge and current. Use Table 5-2
to calculate wire distances for your application if you are using Class B wiring.
Table 5-2. Class B (string) Wiring Distances
Alarm
Current @
24V
0.75 mm
2
1.00 mm
2
1.50 mm
2
2.50 mm
2
4.00 mm
2
DC
Resistance
0.25A 230m 310m 460m 770m 1200m 12.0 ohms
0.50A 120m 150m 230m 380m 620m 6.0 ohms
0.75A 77m 100m 150m 260m 410m 4.0 ohms
1.00A 58m 77m 120m 190m 310m 3.0 ohms
1.25A 46m 62m 92m 150m 250m 2.4 ohms
1.50A 38m 51m 77m 130m 210m 2.0 ohms
1.75A 33m 44m 66m 110m 180m 1.7 ohms
2.00A 29m 38m 58m 96m 150m 1.5 ohms
2.25A 26m 34m 51m 85m 140m 1.3 ohms
2.50A 23m 31m 46m 77m 120m 1.2 ohms
2.75A 21m 28m 42m 70m 110m 1.1 ohms
3.00A 19m 26m 38m 64m 100m 1.0 ohms
Notes:
• Max Distance = distance from SPS to last appliance.
• This table is calculated at 49 degrees Centigrade.
• Distances are based on a 3V drop, and take into account the worst-case panel
output voltage. These distances are based on the worst case of having one single
load at the furthest point.
• If circuit integrity wire is used instead of housing cable in a fire rated enclosure,
reduce wiring distances by 12 m for every 3 m of potential exposure.
Continued on next page
Power Supply Wiring Distances, Continued
Class B NAC
Wiring Table