I bought my place about a year ago and haven't had any problems with my
smoke alarms save one chirping (replacing the battery fixed that) until
last night. Last night my smoke alarms went off as if I had pressed
the test button (only lasted for a few seconds). Today shortly after I
got home from work it went off again, which makes it at least twice
within a 24 hour period. I went around and tested them all and they
worked, but for some reason at least one of them is going off by
The 6 smoke alarms (BRK Electronics Model # 86RAC) are hardwired
together and are powered by 120V and/or battery (currently both).
When they go off all of them go off at once which makes it impossible
to figure out which one is going off. Assuming the smoke alarms
haven't been replaced since the house was built that would make them
around 12 years old.
Is there anything I can do to figure out which one(s) is causing the
problem? I suppose I could disconnect them all from the power and see
if one goes off eventually and hope I hear it, but is there a better
I'm assuming they can be replaced. They have 3 wires labeled white,
black and interconnect.
Get a can of air that you would use for computers and clean them. Do not
touch the lens with your fingers, an q-tip dry works well to break up the
crud then blow clean. If that does not work get new ones. Probably you will
have to get all new ones or replace with an exact match. I have never tried
mixing and matching brands
Last night my smoke alarms went off as if I had
The one going off may have a light lit up. Might be the only way to track
If they are 12 years old, they should be replaced. Sometime in the last few
years, (in the U.S.), a recommended 10-year life span was place on smoke
detectors. There are a couple of people in this group that will fight that
to their last, smoke-filled gasp of breath. For your peace of mind, and
safety, do the (hopefully) simple thing and replace them.
Go to BRK's website and see what they have as a direct replacement. Again,
sometime in the last several years, manufactures have changed to a
low-voltage system. Plug one of those into your set-up, and it will burn
out. Also, there are no plug standards. Easiest is to replace with a BRK, if
they have something. If not, find another brand that has 120 volt
replacements (I know FireX does). It is simple to replace the old plugs with
the new ones. Just don't forget to shut off the power.
Smoke alarms have a finite lifetime. I had the same problem and eventually
after waking up a few times to false alarms at night, I replaced them.
Problem solved. I guess you could replace one at a time but that may not be
worth your time.
On Tue, 31 Aug 2004 00:58:09 GMT, "Dave"
Why, please explain. They are just electronics like a computer, tv,
or radio.... Why should they be different?
Other than a dead battery, or damage from a power surge or lightning
strike, I see no reason they should wear out. There are no mechnical
At the atomic level there are moving parts. The ion chamber has a finite
life time before it gets plated with contaminants or filled with crud. Read
up on this at
http://www.uic.com.au/nip35.htm . As the chamber becomes dirty less current
is generated by the americium ions. The amount of current is used as an
indicator of smoke (less current=more smoke) . As the chamber gets dirty it
mimics this smoke effect and false alarms occur. While cleaning might clear
out some of the crud it will not remove any of the stuff that has plated to
On Tue, 31 Aug 2004 05:44:29 -0500, snipped-for-privacy@UNLISTED.com wrote
(with possible editing):
No, but most smoke detectors have an infrared light source - an LED -
and a phototransistor within a screened and baffled chamber. LED's
actually have a lifetime. 10 years is 87,600 hours (I think) which is
a pretty long lifespan and I think that's reason enough for changing
My built in smoke detector uses regular white lights have had two
burnout in 26 years. 10 years is nothing, lots of parts have an
average life span of 150,000 to 200,000 hours. Heck lots of light
bulbs last 20 or more years of continous duty and some last as long as
40 years. Same is true of lots of electric and electronic parts,
e.g., 40 years is nothing for a transformer.
I had eerily similar scenario happen to me!
I also have BRK smoke detectors, and after a year of living in my current
home, they started going off randomly (always in the middle of the night of
If they are the same model as mine, and it sounds like they are at least
close if not exactly the same (mine has same wires and battery), then you
can tell the one that is going off by the red flashing light IIRC. That
said, the damn things are so loud (especially since, as you said, once one
goes off they all go off) that I couldn't stand to sit there and figure out
which one was the culprit.
I tried vacuuming them out, but then after they started going off again I
plugged my ears and looked to find the one with the light. I made the
mistake of just replacing that one. The others started going off within a
I advise you replace all three with exactly the same brand/model. If you
have a Lowe's near you, I know they carry BRK detectors. I've lived in my
current house for almost 4 years and I've had to replace all of the 3
detectors once, and then another one had to be replaced. BRK is junk IMO,
but the local big box stores only carried BRK or a few other cheesy looking
brands, and nothing but the BRK matched the plug IIRC.
Do yourself a favor and replace all three, and hope that the ones you buy
weren't returned by someone else. That's what I think happened to me for the
one of the three that I had bought originally. That's the problem with an
open return policy though : )
A few years back, I worked on the installation of alarm systems in a 12
story high rise building for the elderly. The building management wanted a
separate smoke alarm system -- separate from the general life safety system
-- with a smoke alarm in each bedroom and an indicator in the control office
indicating which floor it came from. That was easy enough, and we suggested
a particular alarm, but the building personnel had their own suggestions,
and decided on their own brand of alarm. After installation, and while the
building personnel were in the process of bringing in tenants, the smoke
alarms would go off randomly, turning on the main board light and buzzer,
which had to be reset. After checking for smoke, no smoke could be found.
They called me back to find out what the problem was. I made up a box with
some resistors and capacitors and test leads and connected first to the
floor lines. A day later I would go back and take a reading on the leads to
see which capacitors had charged up and then traced the alarm to the floors
with the problem, and then to a specific room. At one location, the
supervisor was with me when we went into the room. I was just about to go
to the bedroom, which was unoccupied, to examine the detector, when it
beeped for just an instant. I looked at the building supervisor; he looked
at me; and we both arrived at the conclusion at the same time that these
detectors were all unstable. He contacted the corporate headquarters, and
they OK'd replacement of all of the detectors with the one's that we had
suggested in the first place. No more problems after that.
They all have a plug on them that connects to the system. Unplug one
of them and keep unplugging one till you find the culprit.
You probably have to also remove the battery on the one you unplug
To get to that plug, you probably have to take the thing off the
ceiling (or wall).
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