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Old 04-03-2012, 10:20 AM
Join Date: Oct 2001
Location: Twirling towards freedom
Posts: 1,976
Why did ALL our smoke alarms go off?

At about 4:30 this morning, I was awakened by the dulcet tones of our smoke alarm. It beeped just a couple of times. A moment later, as we were trying to figure out what was happening, it did it again. The second time, I could distinctly hear that all the alarms (or at least several of them) were going off at the same time. I heard a fainter beep, probably from upstairs, then almost immediately, a louder one, probably in the hall, overlapping the first, and then right after that, the one above us. It was almost simultaneous, all in the space of a second or two, and then stopped.

We checked the whole house just to be sure, but there was no actual smoke or anything we could find that would have triggered the alarms. It was a normal night; no storms, not especially hot or cold or humid or dry. When I was a kid, our smoke alarm got set off occasionally by a bug crawling in, but since it was several alarms at once, a synchronized insect attack seems unlikely - and if that is what it was, we've got bigger problems.

Any ideas?
Old 04-03-2012, 10:45 AM
Charter Member
Join Date: Mar 1999
Location: San Francisco area
Posts: 16,113
Are your alarms interconnected line-powered, or individual battery-powered?

If they're line-powered, setting off all of them at once is normal. My best guess is a speck of dust wandered into one of them just long enough to trigger it.
Old 04-03-2012, 10:47 AM
Charter Member
Join Date: Nov 2002
Location: Scenic Akron, Ohio
Posts: 426
Someone bought a "smart" system and didn't tell you? My fancy-nancy system does this (one goes off, they all go off.) It's a feature, not a bug :P It helps make sure the alarm is heard by everyone in a multi-level home. FTR, mine is battery-powered. This is true of many line-wired systems but you can get them in battery-powered systems as well.

Last edited by Snowcarpet; 04-03-2012 at 10:49 AM. Reason: added last sentence
Old 04-03-2012, 10:52 AM
Join Date: Jul 2009
Posts: 12,056
if the alarms are networked they will all sound together when an alarm triggered, that is a good feature. if the alarms are powered by AC (hard wired) then a power glitch might cause them to trigger.

an alarm might do a low volume beep if the battery (AC powered ones will have a backup battery).

alarms have a lifetime (maybe around 7 years) and need to be replaced.

consult your manual or company website for actual details on your system.
Old 04-03-2012, 10:54 AM
Join Date: Oct 2008
Posts: 1,181
Mine are all hard-wired, battery back-up and linked. When we have power surges they will sometimes do the beeping thing that you described.
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