Edwards Signaling FSC Series - Manual (Page 85)

Appendix A: System calculations
FSC Series Technical Reference Manual 77
Worksheet 1: NAC cable length
NAC1 NAC2 NAC3 NAC4
Total operating current [1] A
Load factor × V/A
Load voltage drop = V
Source voltage 20.4 20.4 20.4 20.4 V
Load voltage drop − V
Minimum voltage = V
Regulated appliance voltage − 16.0 16.0 16.0 16.0 V
Voltage drop [2] = V
Total operating current  A
Maximum resistance = Ω
Wire resistance (Ω/ft) [3] 
Maximum wire length = ft
 2 2 2 2
Maximum cable length = ft
[1] Total of the maximum operating currents for all appliances as specified for FWR power. See
the appliance installation sheets for operating currents.
[2] This voltage drop is valid for regulated notification appliances only. For unregulated
appliances, see “Equation method,” later in this topic.
[3] Use the manufacturer’s published wire resistance expressed in ohms per foot. For typical
values, see Table 26, later in this topic.
Equation method
Appliance operating voltage and current
Regulated notification appliances have an operating range from 16 V to 33 V.
Use 16 V as the minimum appliance voltage when using regulated notification
appliances.