What Causes False Alarms in Your Security System

One of the main concerns using sensor-based traditional alarms is […]

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Date Posted:

February 3, 2024

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One of the main concerns using sensor-based traditional alarms is the number of false alarms.

False Alarms (also known as) a Nuisance Alarm via PIRS

1. The first cause of PIR false alarms is a low unstable voltage at the detector. Test to make sure the voltage at each PIR is above 13 VDC and stable.

2. The second cause is sudden infrared movement heat changes in view of the detector.  Check behind and inside the PIR for insects and identify objects that can move or rapidly change temperature (e.g. pets, vermin, radiator or boiler etc.).  You can adjust the sensitivity of some standard motion sensors. Movement is required to sound an alarm. However, they still cannot tell the difference between a person walking around and a four-legged friend. 

3. The third cause of false alarms is white light momentarily blinding the detector.

4. The fourth cause of false alarms is a direct draught striking the detector.

This causes air convection inside the PIR.  Seal the cable and secret holes. Furthermore, don’t forget the hole where the cable comes through the cavity wall or ceiling.

5 The fifth cause of false alarms is RF/EMI signals. To test susceptibility, you can use a mobile. Simply place the aerial against the PIR casing. Fit an ACT 1376 stabiliser inside the PIR to eliminate RFI.


NoEntry by Sonis – the world’s first plug-and-play, self-installing, all-in-one Intruder alarm which eliminates the need for PIR motion, door and window sensors with pet-friendly intelligence that detects intruders – not pets.  

Other Factors Contributing to False Alarms 

Human Error

This is usually due to the homeowner setting off the alarm by mistake, then forgetting the code or taking too long to enter the code. Guests in your home, including cleaners, tradesmen or babysitters can cause false alarms.

Poorly designed security systems

False alarms are likely if the installer doesn’t consider who lives in the home and how it’s used.  Therefore, having bad wiring and incorrectly placed sensors can also cause false alarms.  

Unlocked or loose doors and windows

Door and window sensors are activated when the connection between the two sensors is disrupted. If a door or window is loose, it can easily be rattled by the wind and trigger an alarm. 

Lack of Maintenance/ Upkeep.

Although security system equipment generally does not need much maintenance, it does require some.  If it stops detecting, this may be because the sensor is faulty. Or, if faulty they can also cause false alarms as they detect intrusions even when there are none.  Thus, correct installation and regular maintenance can prevent issues with your sensors.

Most wireless home security systems contain batteries that occasionally need to be changed and replaced.  These system components typically give audible warnings that the battery levels are low but in some cases, a low battery can trigger a false alarm.

Outdated or old security equipment

You should consider if your equipment needs updating, especially if it has been a long time since your house alarm was installed.

Curtains and other movable objects

In the locations of motion sensors, ensure ceiling fans are turned off and there are no hanging banners or balloons.  You should also close and lock all doors and windows. This is because a breeze can move the curtains and plants causing a false alarm


NoEntry by Sonis has achieved the ability to protect a whole house from one single and attractive device helping to reduce false alarming in domestic properties.  

Police Response 

If you have a monitored alarm system with Police response, it’s not just the installer, maintainer and monitoring company’s responsibility to filter out false alarms, it is yours too.  Police response may be revoked if you have too many false alarms!

The police work on a ‘3 strikes and you are out’ system.  This means that, if you experience a false alarm three times within 1 month, the Police will downgrade you and not treat your alarm alerting as a priority.

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