Security & Fire Protection Systems/hard wired smoke alarms


We have three smoke alarms in our house: one in our bedroom (on the lower floor) and two upstairs. Our smoke alarms went off in the middle of the night and we could not smell any smoke or find any reason for them ringing. I noticed that the alarm in our room, which has a steady burning green light, also has a red light that flashes every 10 seconds. The 2 upstairs alarms don't have this flashing red light. Does this indicate that the alarm in our room is the one that detected the smoke? (Please, note that we did have a fan on in our room, to cool it down at night). Also, what is the life expectancy of wired in smoke alarms? Ours are 4 to 5 years old. Thank you, in advance for your answer and time.

Hello Reenie, and thanks for your question.

There are many different hard-wired smoke detectors, and in order to answer your question, I'll need the make and model of yours. (The way the LEDs are interpreted are different in many cases.)

This information is generally found on the back of the detectors, so you'll have to take one down to see it. Most detectors have a base that's attached to the ceiling, and the detector twists into the base. So a quarter turn counter-clockwise is usually all it takes. You won't have to disconnect any wires as there will be enough slack to pull it down a few inches so you can get the information.

While you're there, look for the manufacture date. The general rule is that detectors should be replaced every ten years.

Best Regards,


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Dave Neuweiler


The design and application of burglary and fire systems for homes and businesses. Helping alarm owners understand how their system works. Helping to troubleshoot false alarm problems. Questions about monitoring issues.


Over a quarter century in the industry. Experience in installation, service, and monitoring centers. Training manager for a national protective services company; director of education and training for a national trade organization for for alarm dealers.


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