What's wrong with my fire alarm?

July 28, 2008 9:13 AM

My fire alarm started going off randomly last night, several times, after doing so inter-mittently over the last year. What is causing this, and what can I do?

So here's the symptoms... we moved in about 1.5 years ago, and the fire alarms went off randomly like once every few months. Usually it would just do the alarm cycle 3 times, like beepbeepbeep... beepbeepbeep... beepbeepbeep... and stop (this is the same thing it does when you press the test button...)

I've replaced all the batteries (although none of them had the check battery light on, or were making that obnoxious chirping sound)

Then last night it did this at 2am, 4am, 4:50am and about 5:30am. Because nothing was on fire and I wanted some sleep, I removed *all* of the fire alarms (unplugged them from the ceiling, removed the batteries).

These are "normal" fire alarms, same as in every house I've ever lived in. They plug into a small outlet in the ceiling, they're "networked" together so that if one goes off, they all do. What might cause this? What can I do to fix it? Would one "bad" one convince the network of them that an alarm was going off? Bad wiring? I'm assuming there's no central control panel for them in the house (I've never seen one) but maybe there is some where?

posted by RustyBrooks to home & garden (13 comments total)

Do they check for carbon monoxide as well, I had this problem with the one outside our water heater closet when the vent was clogged.
posted by iamabot at 9:23 AM on July 28, 2008

Could be schmutz inside one or more detectors.
posted by ROU_Xenophobe at 9:24 AM on July 28, 2008

Could be dust getting into the sensor. This happened to one of ours. I think after a while smoke detectors just get old and need to be replaced.
posted by drinkcoffee at 9:46 AM on July 28, 2008

Our house is less than 5 years old - I would hope they don't need replacement already...

They are not carbon monoxide detectors... we had to get a seperate one of those.

I guess I can replace them and see what happens but I'm going to be pisssed if I buy like 7 new ones and the same thing happens.

(Also, why does this stuff only happen at 4am and not, like, noon....)
posted by RustyBrooks at 9:48 AM on July 28, 2008

I would replace one first and see what happens. You could have some sort of electrical problem. If they plug into outlets, do you have a security alarm system? If so, then you might have the entire system looked at.

In the meantime, you might grab a couple of battery-operated alarms just to make sure you're actually protected. If you call your local non-emergency number (311 in most parts of the US), you might find that you can get a couple of those for free.
posted by Lyn Never at 9:53 AM on July 28, 2008

The outlets they plug into appear to be solely for the fire alarms. They're sort of standard around here, every house I've had in the last 5 years has had identical ones, whether it also had a security alarm or not (we don't currently have a security alarm)

I guess replacing them all is the way to go. I'll go by and see how much they are.
posted by RustyBrooks at 10:13 AM on July 28, 2008

Why not try blasting each of them with some compressed air to clear out any crud?

Warning: unplug first. The crud flying around might well be read as smoke.
posted by ROU_Xenophobe at 10:27 AM on July 28, 2008

This happened to me once and just about drove me nuts. My reaction was identical to yours. I'm standing there in the middle of the night in my underwear holding the smoke alarm I just disconnected from the ceiling, trying to figure out why the damn thing kept going off intermittently, when I felt the slightest little tickle on my hand. Looking down I saw a tiny spider crawling up my hand from the alarm. I opened up the alarm, and, sure enough, there was his web. The little guy was nocturnal, and whenever he started his midnight shenanigans he'd randomly trigger the alarm. (Most smoke alarms detect particles, and this little rascal, or some part of his web, was evidently small enough to be considered a "particle").

Cleaning out that alarm, and all the others, resulted in the total elimination of the problem. I recommend a good dusting and/or vacuuming of all your alarms…should do the trick.

Pleasant dreams.
posted by dinger at 10:33 AM on July 28, 2008

Dinger--I was just coming in to type "spiders". They have happened to me more than once. One time, it was a whole nest of baby spiders who spilled out on top of me at 3:00 am in my own personal horror movie.
posted by crush-onastick at 10:34 AM on July 28, 2008

Same thing to me but my alarm and not fire alarm...
At 3:00 am mine would go off about once a month, turned out that AT&T was testing their lines and disconnecting the phone connection alerting my alarm system tripping the siren.
Sounds to me like you may be getting some minuscule electrical change that's upsetting the alarm.
Possibly get surge protectors or something of the sorts?
posted by doorsfan at 10:36 AM on July 28, 2008

Get a can of Dust-Off and give the alarm a good spray (after taking out the battery). If the problem ends up being spiders, invert the can and spray. It'll freeze 'em.
posted by dws at 8:46 PM on July 28, 2008

I had this problem once. Our smoke detectors were going off in the middle of the night and irritating the hell out of all of us. One of us worked for an engineering firm testing ground compaction at construction sites. He had some big-ass tool to do this with, that apparantly involved some radioactive isotope, as the thing had stickers indicating that all over. He would bring it in from his truck at night, and leave it in the hall under the smoke detector. We eventually figured out that this was the problem. It was emitting some minor radiation or something and setting off the detectors. When he stopped storing it there, the problem went away.

This is probably not your problem, but it's possible.
posted by Jupiter Jones at 9:57 AM on July 31, 2008

could be bugs disrupting the sensor, if you have the photoelectric type of detector.
posted by kenliu at 2:53 PM on August 10, 2008