Why Does My Fire Alarm Keep Going Off Unexpectedly

Is your fire alarm’s incessant chirping driving you crazy? If so it is best that you assume the worst before you start thinking of further reasons why the alarm may be going off. Besides the obvious reason (having a fire in your home), there are a few potential causes to your fire alarm going off unexpectedly including dust, insects crawling inside your smoke detector, humidity and low batteries. 


Much like every room in your house, over time, dust can build up on your smoke alarm’s sensor. This obstruction of the sensor can cause it to confuse dust for smoke, setting your alarm off. The best way to check this is by opening the device. Use a vacuum cleaner nozzle to either suck or blow the dust. Be warned that while doing so it may go off again, which is absolutely normal, so don’t worry about it. If this was what was setting the smoke alarm off in the first place this should resolve it.

Vaccum cleaner to stop fire alarm going off

Humidity and Steam

Humidity and steam from showers or cooking appliances are also common triggers. Much like with dust, ionisation models are highly susceptible to moisture particles. It is possible that your smoke detectors have not been placed in optimal locations. They shouldn’t be located close to kitchens as the smoke from burning food or the steam from boiling water can be the cause of false alarms. Or it may just be the fact that you simply live in an area with high humidity in the air.

Steam causing fire alarm to go off unexpectedly


In general smoke detectors are insect-proof but exceptions can occur. There are two types of smoke detectors photoelectric and ionisation models as we previously mentioned. In Photoelectric models it is more likely for a small insect to crawl inside and set off the alarm. This is because of the way they are programmed to work. If a room gets smoky enough to block the light beam the alarm will go off. They are quite big but not very sensitive. While ionisation models go off once enough smoke has entered the alarm and it has protective insect screens to impede small bugs from entering.

insects stuck in fire alarm causing it to go off

Low batteries

This one you may already know. It is a very simple cause but it can be one of the most annoying,  as your smoke detector will ‘chirp’ once a minute when your battery starts getting weak and needs replacing. It is recommended to change a smoke detector’s batteries every 12 months. You may not want to wait until it gets really annoying so you can just change the batteries yourself before it goes off. However, we understand that this can represent some trouble which is why there is no need to change the batteries of the East Midlands Security & Fire smoke and carbon monoxide detectors as they are connected to the alarm system.

low batteries causing fire alarm to go off


End of life

Have you ever considered that it is not just the food you buy that expires but your smoke alarm does as well? The sensors are bound to degrade over time, reducing their effectiveness and sensitivity. A Smoke alarm certified to British Standard EN14604:2005, will have a “replace by” date that you can check, but in general smoke detectors should be replaced every 10 years.

man trying to fix a broken fire alarm

It is important to provide maintenance with some regularity. At East Midlands Security and Fire we perform annual maintenance visits to ensure the highest standard of protection to you and your family. Get in touch to find out more at 01455 698 964 or send us an enquiry via our online contact form.