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Before wiring from any type of power supply to notification appliances, check Tables 5-1
and 5-2 for wiring distances.
Table 5-1 lists the maximum distances from the NAC terminal block to the last appliance
in a Class A (loop) configuration, depending on wire gauge and current. Use Table 5-1 to
calculate wire distances for your application if you are using Class A wiring.
Table 5-1. Class A (Loop) 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 120m 150m 230m 380m 620m 6.0 ohms
0.50A 58m 77m 120m 190m 310m 3.0 ohms
0.75A 38m 51m 77m 130m 210m 2.0 ohms
1.00A 29m 38m 58m 96m 150m 1.5 ohms
1.25A 23m 31m 46m 77m 120m 1.2 ohms
1.50A 19m 26m 38m 64m 100m 1.0 ohms
1.75A 16m 22m 33m 55m 88m 0.86 ohms
2.00A 14m 19m 29m 48m 77m 0.75 ohms
2.25A 13m 17m 26m 43m 68m 0.67 ohms
2.50A 12m 15m 23m 38m 62m 0.60 ohms
2.75A 10m 14m 21m 35m 56m 0.55 ohms
3.00A 10m 13m 19m 32m 51m 0.50 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
Overview
Class A NAC
Wiring Table