Spectrex 20/20U (UB) - UV Flame Detector - Manual (Page 45)

Spectrex Inc. - SharpEye™ UV Flame Detector Manual – TM 20/20UB Rev. E, August 2004
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Appendix A - Wire Selection Tables
G ENERAL I NSTRUCTION FOR E LECTRICAL W IRING :
1. Refer to Table 10 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, length of wires.
2. Refer to Table 11 to select wire gauge for detectors power supply wires. DO
NOT connect any device or load to detectors supply inputs.
Table 10. Maximum DC resistance at 68°F for copper wire
AWG mm
2
Ohm per
100 ft.
Ohm per
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
Wiring Gauge
1 Select “No. of detectors” connected on one circuit.
2 Select “wiring length” per your installation requirements.
3 Refer to “Power Supply Range” for voltage extreme applied.
Table 11. 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