Wire Requirements
150 MS-5UD/MS-10UD Series   PN 52626:B  8/01/2008
APPENDIX D   Wire Requirements
Connecting external system accessories to the main circuits must be carefully considered to ensure 
proper operation.  It is important to use the correct type of wire, gauge and run length for each 
circuit.  Reference the chart below to specify wire requirements and limitations for each circuit.  
Table D.1  FACP Wire Specifications
CIRCUIT CONNECTIONS WIRE REQUIREMENTS
Circuit Type Circuit Function Wire Type and Limitations
Recommended 
Max. Distance
Feet (meters)
Wire Gauge
Initiating Device 
Circuit
(power-limited)
Connects to 
Initiating Devices
Untwisted, unshielded wire
(maximum loop resistance 
not to exceed 100 ohms)
Distance limitation 
set by 100 ohm 
resistance limitation
12-18 AWG (3.25 - 0.75 mm
2
)
ANN-BUS  
(EIA-485)
power-limited
Communication 
for ANN-BUS 
annunciator and 
relay modules
Twisted pair a maximum 
loop resistance of 120 ohms
6,000 (1,800 m)
12-18 AWG (3.25 - 0.75 mm
2
)
ANN-BUS 
Power
Power for 
ANN-BUS 
annunciators
Refer to  "ANN-BUS Devices" on page 38 for information on device wiring
24 VDC 
Regulated, 
resettable, 
nonresettable
Power for 
accessories and 
4-wire devices
Untwisted, unshielded wire Distance limitation 
set by 4 volt 
maximum line drop
12-18 AWG (3.25 - 0.75 mm
2
)
Auxiliary 
Trouble Input
Open Collector 
trouble input for 
CHG-75, 
CHG-120F, etc.
Single conductor Distance limitation 
20 feet in same 
room
18 AWG (0.75 mm
2
)
Remote Sync 
Output
Provides strobe 
and normal sync 
for remote NAC 
power supplies
Untwisted, unshielded pair 
wire
Distance set by 295 
ohm resistance 
limitation
12-18 AWG (3.25 - 0.75 mm
2
)
NAC Outputs Connects to NAC 
devices or Release 
devices
Untwisted, unshielded pair 
wire Refer to Section D.1 and Section D.2 on page 151.