Specifications

Calculations C
SHM80001
SAFETY HI-TECH
Quaestor-SZU Releasing Fire Control Panel - Installation and Operation Manual
Revision E03.04
109 of 155
3 Identify the maximum resistance of the wire gage used in the circuit (R
wiremax
) when using 18 AWG copper.
An 18 AWG solid copper wire is 6.385 Ohms at 1000FT using the Resistance Table below:
4 The calculation for the minimum output voltage of the NAC is:
V
outmin
= V
panel
X 85%
= 24 VDC X 85%
5 The calculation for voltage-drop across the length of the wire is:
V
drop
= V
outmin
- V
opmin
= 20.4 VDC - 16 VDC
6 The calculation for maximum wire length of this circuit is:
L
max
= 1/2 ( V
drop
/ I
max
) / R
wire
where,
= 1/2 [ ( 4.4 / 0.6286 ) / ( 0.006385 Ohms / FT ) ]
Gage Resistance / 1000Ft @ 68F
R
wire
18 AWG 6.385 Ohms
0.006385 Ohms / FT
16 AWG 4.016 Ohms
0.004016 Ohms / FT
14 AWG 2.525 Ohms
0.002525 Ohms / FT
V
outmin
= 20.4 VDC
V
drop
= 4.4 VDC
L
max
= 548 FT