User Guide
18
 • When alarms are hardwire interconnected, all interconnected units must be powered from a single circuit.
 • A maximum of 24 Kidde Safety devices may be interconnected in a multiple station arrangement. The interconnect 
system should not exceed the NFPA interconnect limit of 12 smoke alarms and/or 18 alarms total (smoke, CO, Smoke/ 
CO Combination, heat, etc.). With 18 alarms interconnected, it is still possible to interconnect up to a total of 6 remote 
signaling devices and / or relay modules.
 • The maximum wire run distance between the first and last unit in an interconnected system is 1000 feet.
 •  Figure 5 illustrates interconnection wiring. Improper connection will result in damage to the alarm, failure to 
operate, or a shock hazard.
 • Make certain alarms are wired to a continuous (non-switched) power line.
NOTE: Use standard UL Listed household wire (as required by local codes) available at all electrical supply 
stores and most hardware stores.
Additional
Alarm
REDBLACK
WHITE
Additional
Alarm
RED
BLACK
WHITE
FUSE OR CIRCUIT BREAKER
REDBLACK
WHITE
Kidde Relay Module
SM120X, CO120X
or both 
Optional 
Accessory
First
Alarm
Figure 10-A, Interconnect Wiring Diagram
  Wires on alarm harness:  Connected to: 
  Black:  Hot side of AC line 
  White:  Neutral side of AC line 
  Red:  Interconnect lines (red wires) of other 
    units in the multiple station set-up










