4-Wire Smoke Detector Home Fire alarm 2 wire for power 2 wire with relay output N/O or N/C contact connection with home security controller. The smoke detector has 2 LED for indication of working status. Smoke Detector has built-in buzzer for sound alarm. 4-wire smoke detector is connected with home security system to send alarm to dialer and notify mobile at the same time. The smoke detector meetes CE EN54 Smoke security requipment. Life time for Smoke detector is 10 Years. Regular inspection, test and maintence is required for the Home Fire alarm Smoke Detector.