Edwards Signaling FireShield 10 Zone - Manual (Page 45)

Calculations
FireShield Technical Reference Manual A.3
Notification appliance voltage drop calculation
NAC 1 voltage drop calculations
Circuit length Total circuit
current [2] Wire resistance
per 1000 ft [1] Voltage
drop
feet x amps x Ω ÷ 1000 =
Panel
voltage Voltage
drop End of line
voltage [3] Voltage
drop Panel
voltage Voltage
drop %
[4] – = ÷ [4] =
NAC 2 voltage drop calculations
Circuit length Total circuit
current [2] Wire resistance
per 1000 ft [1] Voltage
drop
feet x amps x Ω ÷ 1000 =
Panel
voltage Voltage
drop End of line
voltage [3] Voltage
drop Panel
voltage Voltage
drop %
[4] – = ÷ [4] =
NAC 3 voltage drop calculations
Circuit length Total circuit
current [2] Wire resistance
per 1000 ft [1] Voltage
drop
feet x amps x Ω ÷ 1000 =
Panel
voltage Voltage
drop End of line
voltage [3] Voltage
drop Panel
voltage Voltage
drop %
[4] – = ÷ [4] =
NAC 4 voltage drop calculations
Circuit length Total circuit
current [2] Wire resistance
per 1000 ft [1] Voltage
drop
feet x amps x Ω ÷ 1000 =
Panel
voltage Voltage
drop End of line
voltage [3] Voltage
drop Panel
voltage Voltage
drop %
[4] – = ÷ [4] =
Notes
[1] Use 3.5 Ω for 12 AWG and 2.5 sq mm wire, 5.2 Ω for 14 AWG and 1.5 sq mm wire, 8.0 Ω for 16 AWG and 1.0 sq mm wire,
and 13.0 Ω for 18 AWG and 0.75 sq mm wire.
[2] Use the filtered 20 Vdc Average Operating Current ratings found on the installation or catalog sheet of each device.
[3] Cannot drop below 17 Vdc.
[4] 18.6 V for 230 V at 50 Hz, 18.8 V for 230 V 60 at Hz, 18.9 V for 120 V at 60 Hz