Smoke Detector

Smoke Detector Trouble

Jesse Kuhlman Uncategorized

Smoke Detector Trouble!

It’s 2am and the smoke detectors are going off! Is it a fire? I don’t smell smoke as I walk around the house.  What is it? Why are the smoke detectors going off in the middle of the night again?

Does this sound familiar? We have all been there. Our smoke detectors are going off for seemingly no reason and quite honestly, driving us crazy!

This article will discuss issues with hard wired photoelectric detectors with battery backup.  These are the units currently required in Massachusetts and most commonly found in residential homes.

First things first, how do these things work?

By today’s code, the detectors in a home must be interconnected. This means if one detector initiates an alarm (or falsely initiates, more on this later) all the smoke detectors on the system will go into alarm.  The obvious reason for this is that if the alarm in the basement goes off and you are in your bedroom, you will be alerted to the issue.

Massachusetts requires photoelectric smoke detectors which are great at detecting slow burning / smoldering fires. Within the smoke detector there is a smoke chamber with a light source aimed away from a light sensor.  When smoke enters the chamber, the light is reflected into the light sensor causing the alarm to go off. 

Something to keep in mind with interconnected systems:

If you live in a single family home, all your smoke detectors will be connected together. (If they are up to today’s code)

If you live in a multifamily, it will work a little different.  Let’s take a 3-family home for example.  Each unit will have its own interconnected system, which does NOT connect to the other units or the common space.  The common space (think stairways, basement space, anywhere that is outside the units and still within the building) will have its own interconnected system that does NOT connect to any units.

You may be asking yourself, why don’t they all connect? Nuisance issues! Imagine every time your upstairs neighbor is cooking and burns their rice, YOUR smoke detectors would go off!  This would be a nightmare and the main reason for them being separate.

Distinguishing the different sounds

Low Battery Chirp

The detector with the low battery will chirp once every minute or so.  NO other detectors will chirp unless they have a low battery as well.  The sound they make while chirping is not super loud (not even close to the sound they make in full alarm) but loud enough to be annoying and prompt you to change the battery sooner than later.  Once the battery is changed in the smoke detector, the chirp will stop.

Full Alarm

Once a smoke detector detects smoke, it will set all the smoke detectors off that are interconnected to it.  The sound they make in full alarm is ear piercing and cannot be mistaken with the “low battery” chirp sound.

There is NO SMOKE, what the..?

Remember when we talked about how the smoke chamber works, reflecting light into a light sensor? Well dust (maybe even insects) can cause the light to be reflected and the alarm to go off.

Keeping these babies CLEAN is a big part of smoke detector maintenance.   We recommend vacuuming around the smoke detector regularly. This helps keep any potential dust from entering the smoke chamber.  When you look at your smoke detector on the ceiling, you will see some slots on the face, and some more on the side. Use a vacuum with a brush end and hit the face, then around the outside a couple times.

What else can go wrong with these things?

But wait, there’s more good news!

We have found that fluctuations in voltage can cause smoke detectors to randomly go off.  Why this is, I’m not sure but it happens.  This is usually the cause of those middle of the night false alarms. The power company may be changing something on their end, causing the voltage to drop a small percentage which the smoke detectors are sensitive to, throwing them into full alarm.

Figuring out which alarm is causing the false alarm:

Alright, so you understand the difference between the low battery chirp and full alarm. You have been keeping them clean, but they still have a false alarm. 

This will be tricky to do, but try your best – While they are going off, look for the smoke detector with a fast blinking red light.  Most brands work this way, the alarm initiating them all to go off will have a fast blinking light.  The others will not.  If you can find this one, you can press and hold the silence button on the detector, which will silence the whole system.  If you press silence on the detector that is not initiating, it will only silence that one detector, not them all.

Once you find the detector that is causing the issue, it will most likely need replacing. You can twist off the detector from the wall (the face of the detector will have an arrow for direction to twist for removal), which will detach the detector from the ceiling plate.  Now there will be a three wire connector coming out the box and connecting to the detector.  This connector needs to be pulled off.  The brand pictured below has a connector which needs to be pinched to disconnect, while some other brands will be just pull out without pinching.

If all of this seems to confusing, you can go the old school route and grab a broom and whack all the detectors off the ceiling until they stop going off!! Yes I’ve seen this many times, no judgment J

Removing Alarm:

The detector pictured (Kidde brand) detaches from the ceiling by twisting to the right (clockwise)

Once the detector is removed from the ceiling, the three pin connector will be revealed.   This brand requires you to pinch the connector, releasing it from the detector.

And just like that, it’s removed!

How old are my smoke detectors?

A good recommendation is to replace your smoke detectors every 7 years.  All smoke detectors have a date on the back on them. Simply remove one and check the date.

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Calling an electrician to fix smoke detectors that have false alarms:

We get these calls from customers all the time.  By the time we get to the home, the detectors will have stopped going off. How are we to determine the one causing the issue if they are no longer in an alarm state? We can’t.

THE BEST thing you can do as a homeowner is to find the one initiating the alarm when they are going off.  This way that one can be replaced.