Appendix B Wiring Instructions; General Instructions For Electrical Wiring - Emerson Rosemount 975UF Reference Manual

Reference Manual
00809-0100-4977
B Wiring instructions
B.1

General instructions for electrical wiring

Follow the instructions detailed in this section for determining the correct wire gauge to
be used for this installation.
1. Use
2. Use
Table B-2: Wiring Length in Meters (Feet)
Number of Recommended wire diameter (AWG)
detectors
24 18
20 18
16 20
12 20
8 20
4 and less 20
m (ft) 50 (164)
Max. length from power supply to last detector
Rosemount 975UF
Table B-1 to determine the required wire gauge/size for general wiring, such as
relay wiring. Calculate the permitted voltage drop with respect to load current, wire
gauge, and length of wires.
Table B-1: Maximum DC Resistance at 68 °F (20 °C) for Copper Wire
AWG # mm
20 0.52 - 0.61
18 0.81 - 0.96
16 1.22 - 1.43
14 1.94 - 2.28
Table B-2 to select wire gauge for power supply wires. Do not connect any
circuit or load to detectors' supply inputs.
• Select number of detectors connected in one circuit.
• Select wiring length per installation requirements.
• Refer to power supply range for voltage extreme applied.
16 14
16 14
18 16
18 16
18 16
18 16
100 (328) 150 (492)
2
Ohm per 100 ft.
1.07
0.67
0.43
0.27
N/A
N/A
14
14
14
16
200 (656)
Wiring instructions
June 2021
Ohm per 100 m
3.50
2.20
1.40
0.88
Power supply
range (Vdc)
N/A 22-32
N/A 22-32
N/A 22-32
N/A 20-32
N/A 20-32
14 20-32
240 (820)
55