Mircom FR-320 Series, Installation And Operation Manual

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Field Wiring
7.8 Wiring Tables and Information
7.9 Four-Wire Smoke Power (regulated)
Four-wire smoke power is provided for four-wire smoke detectors. This filtered supply is
supervised therefore a short will disconnect the power and the common trouble is active. The
power is reconnected after the 'RESET' key is pressed. See
17.0 Appendix E:
Specifications on page 101 for supply rating.
Table 3 Initiating Circuit Wiring Distances
WIRE GAUGE MAXIMUM WIRING RUN TO LAST DEVICE
AWG FEET METERS
22 2990 910
20 4760 1450
18 7560 2300
16 12000 3600
14 19000 5800
12 30400 9200
Notes: For Class A the maximum wiring run to the last device is divided by two.
Maximum loop resistance should not exceed 100 ohms.
Maximum capacitance of 0.5uF total on each initiating circuit.
Table 4 Indicating Circuit Wiring Distances
TOTAL
SIGNAL
LOAD MAXIMUM WIRING RUN TO LAST DEVICE (ELR) MAX. LOOP
RESISTANCE
18AWG 16AWG 14AWG 12AWG
Amperes ft m ft m ft m ft m Ohms
0.06 2350 716 3750 1143 6000 1829 9500 2895 30
0.12 1180 360 1850 567 3000 915 4720 1438 15
0.30 470 143 750 229 1200 366 1900 579 6
0.60 235 71 375 114 600 183 950 289 3
0.90 156 47 250 76 400 122 630 192 2
1.20 118 36 185 56 300 91 470 143 1.5
1.50 94 29 150 46 240 73 380 115 1.2
1.70 78 24 125 38 200 61 315 96 1.0
Notes: For Class A wiring the resistance in ohms is multiplied by two.
Maximum voltage drop should not exceed 1.8 volts.
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