Kidde VM-1 Technical Reference Manual

Appendix A: System calculations
P/N 3101890-EN • REV 006 • ISS 21JUN18 179
Worksheet method
Use this worksheet to determine the maximum cable length of a notification appliance circuit for a given number
of appliances.
Use this worksheet only if all the appliances are regulated. That is, they must have a minimum operating voltage
of 16 V. For other appliances, use the “Equation method.”
Worksheet 1: NAC cable length
[NAC1 or
Source 1]
[NAC2 or
Source 2]
[NAC3 or
Source 3]
[NAC4 or
Source 4]
Total operating current [1]
A
Load factor
×
0.0
0.0 0.0 0.0
V/A
Load voltage drop
= V
Source voltage
22.4
22.4 22.4 22.4
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 DC power. See the appliance
installation sheets for operating currents.
[2]
This voltage drop is valid for regulated notification appliances only. For special application appliances, see
“
Equation method” on page 180.
[3]
Use the manufacturer’s published wire resistance expressed in ohms per foot. For typical values, see Table 72
on page 180, later in this topic.

Kidde VM-1 Specifications

General

Brand	Kidde
Model	VM-1
Category	Fire Alarms
Language	English