False Fire Alarms Waking You Up?

This post was written in 2011. Please read our new guide to troubleshooting beeping smoke alarms.

A common complaint we hear about are smoke alarms that go off in the middle of the night. There are a number of reasons and steps you can take to minimise the possibility of nuisance alarms waking you up.

Smoke alarms with low batteries will emit a beeping sound to indicate that the batteries require replacement. Batteries are at their weakest at night when it is cooler and you can therefore get low battery warnings which can wake you up. If it is a low battery warning sound (every few minutes or so), change your batteries. Make sure you use good quality batteries, as cheap batteries may not be strong enough to power the alarm and again cause the alarm to bleep during the night .

The issue of low batteries may  also apply if you have mains powered smoke alarms, as most mains powered alarms contain a backup battery to power the alarm in case of power failure.

If a mains powered smoke alarm gives an irregular warning sound, it might also indicate that the mains power supply is interrupted. Some smoke alarms have a green LED light on the outer case to show that the smoke alarm is connected to the mains power. If the green LED is not lit it can be an indication that there has been an interruption in the mains power supply and that the alarm will be using the back up battery as the power source.

Should the alarm emit a continuous sound, check first of all that there are no signs of a fire. False alarms can be caused by condensation or insects finding their way into the alarm. To eradicate this type of false alarm try to vacuum out the inside of the smoke alarm as thoroughly as possible and ventilate the room to reduce the condensation present.

When a smoke alarm has reached the end of its life it might also start to sound an intermittent beep as and when the alarm starts to become faulty. Check the manufacturing date of the smoke alarm. Smoke alarms need replacing after ten years.

In all cases of nuisance beeping or false alarms do not disconnect your alarm or leave the alarm without batteries fitted. This would leave you unprotected in the event of a fire and you would not receive any warning to evacuate the building.

To ensure that you have done everything possible to minimise the chances of false alarms and nuisance beeping take advantage of our free reminder service to alert you to replace batteries or replace the smoke alarm unit.


  1. We have an intermittent beep – we have two alarms Aico EI141RC & Aico EI144RC. I have replaced batteries in both – and now replaced the removeable part of the EI141RC (not the base). And we still have intermittent beeps and an occasional four beep pattern.

    I have ordered a replacement for the EI144RC as well because it is 8 years old, but as the beeping is coming from the EI141RC I am not sure this will help either!

    Any suggestions?

    1. Hi Chris, one of the most common causes for unexplainable beeps like yours is a carbon monoxide in the vicinity with a low battery beep, maybe in a drawer or just hidden away a bit. It is really difficult to locate the true origin of these beeps! If it’s not that it could be an interrupted mains power supply; is the green light on? If it is then you might have to get electrician out to check the wiring and communication cable between units. Fingers crossed it is just a CO alarm nearby beeping away. Harry

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