Appendix a - wire selection tables – Spectrex 20/20SI Triple IR (IR3) Flame Detector User Manual
Page 47
Spectrex Inc. - SharpEye
TM
IR3 Flame Detector Manual – TM 20/20I, Rev. (6) August 2004
39
Appendix A - Wire Selection Tables
General Instructions For Electrical Wiring
1. Refer to Table 14 to determine the required wire gauge for general wiring,
such as relay wiring. Calculate the permitted voltage fall with respect to
loads current, wire gauge and length of wires.
2. Refer to Table 15 to select wire gauge for power supply wires. DO NOT
connect any circuit or load to detectors’ supply inputs.
Table 14: Maximum DC resistance at 68˚F for copper wire
AWG # mm
2
Ohm per 100 ft.
Ohm/100
meter
26 0.12
-
0.15 4.32
14.15
24 0.16
-
0.24 3.42
11.22
22
0.30 - 0.38
1.71
5.60
20
0.51 - 0.61
1.07
3.50
18
0.81 - 0.96
0.67
2.20
16
1.22 - 1.43
0.43
1.40
14
1.94 - 2.28
0.27
0.88
12
3.09 - 3.40
0.17
0.55
10
4.56 - 6.64
0.11
0.35
A. Select "Number of detectors" connected in one circuit.
B. Select "wiring length" per your installation requirements.
C. Refer to "power supply range" for voltage extreme applied.
Table 15. Wiring length in feet (meter)
No. of
Detectors
Recommended Wire Diameter
Power Supply
Range (VDC)
24
18
16
14
-
-
22-32
20
18
16
14
-
-
22-32
16
20
18
16
14
-
22-32
12
20
18
16
14
-
20-32
8 20
18
16
14
-
20-32
4
and
less
20
18 16 16 14
20-32
Feet
164
328 492 656 820
(meter)
(50)
(100) (150) (200) (250)
Max. Length from Power Supply to Last
Detector