Expert: Dave Neuweiler - 6/9/2006

Question
I have BRK Electronics Model #4120B smoke detectors.  I've changed all the batteries, and vacuumed the vents, but I still get intermittent false alarms.  The false alarms happen once or twice a day (or night!) and last for a couple of seconds.  How do I trouble shoot this problem?

Answer
Hello David, and thanks for your question. There are a couple of things you can look at.

First, here's a link to the manual for your detectors. (According to the BRK website, your model has been discontinued.)

http://www.brkelectronics.com/downloads/safety_products/user_manuals/smoke_alarm...

On page 6, there is a list of places to avoid for smoke detector installations. If any of your detectors is in or near one of these, then moving it may solve the problem.

Second, since you have more than one detector, and they are interconnected, when one trips, all will sound the alarm. That makes finding the one that's setting everything off difficult.

If you have only a few detectors, and they are several years old, you could consider replacing all of them. Some manufacturers recommend replacing detectors after 7 years.

If you want to try to find which individual detector is falsing, you'll need to do a little work. Each detector is connected to 3 wires. The black and white wires are for 120 volt AC power. The orange wire is the one that interconnects the detectors. If you disconnect the orange wire from each detector, then only the one that is falsing will sound the alarm. Note that this is only useful as a troubleshooting method -- you cannot leave them that way.

Be sure to turn the AC power off to the detectors at the breaker box before doing this kind of work, or call an electrician to do the work.

If you find a single problem detector, BRK should have a replcement that is compatible with the remaining ones.

I hope this helps, and please write again if you have a follow-up question.

Best Regards,

Dave