Description this wired smoke detector connects to any normally closed (nc) or normally open circuit alarm system. when programmed, the alarm system's siren will sound when smoke is detected. the smoke detector will also beep in the room where it is installed so you know which smoke detector caused the alarm. once the smoke has dissipated, the smoke detector will automatically reset itself. wired connections this wired smoke detector uses 4 wires in total. two wires are for power (+) and (-). two wires are used for the normally closed (n/c) or normally open (n/o) circuit. features test button on smoke detector for easy testing. photoelectric detection to reduce false alarms (i.e. cooking in the kitchen) sensitivity control inside detector. n/o & n/c selection jumper inside detector. automatic reset when smoke dissipates.