False alarms can be frustrating, disruptive and costly. They can disturb neighbours, interrupt your business, cause unnecessary callouts and reduce confidence in your security system.
For monitored systems, repeated false alarms can also create issues with alarm response, so it is important to understand what may be causing them and how to reduce them.
At MES Systems, we install, maintain and monitor intruder alarm systems for homes, businesses, schools and organisations across Nuneaton, Warwickshire and the wider Midlands. In our experience, many false alarms can be avoided with good system design, regular maintenance and simple day-to-day checks.
Here are some of the most common causes of false alarms.
1. Lack of regular maintenance
One of the most common causes of false alarms is an intruder alarm system that has not been properly serviced or maintained.
Over time, detectors can become dusty, batteries require changing, and equipment can develop faults. Regular maintenance helps identify these issues before they lead to unwanted alarm activations.
During a routine service, an engineer can check the condition of detectors, contacts, batteries, control equipment, signalling and other key parts of the system.
2. Doors or windows left open
False alarms can occur when a door or window is left open, unlocked or not properly secured before the alarm is set.
This can allow movement from people or animals to trigger the system.
Before setting your alarm, check that:
- Doors are properly closed and locked
- Windows are closed and secure
- Patio doors and bi-fold doors are locked
- Roller shutters, gates or external doors are secure where relevant
- No one is still inside the protected area
- The correct entry and exit route is being used
This is especially important in commercial premises where several people may be responsible for closing the building.
3. Insects and spiders near detectors
Insects and spiders can cause false alarms if they crawl across or near a detector lens. This can be more common during warmer months when doors and windows are left open and insects are more likely to enter the property.
To reduce the risk:
- Keep detectors free from insects and cobwebs
- Remove moths, flies, bees and other insects before setting the alarm
- Keep areas around detectors clean and clear
Avoid spraying cleaning products or insect sprays directly onto detectors, as this could damage the equipment.
4. Cobwebs around detectors
Cobwebs can hang in front of or below a detector and move with air flow, creating unwanted activations.
They can be difficult to spot, particularly in corners, warehouses, stockrooms, garages and outbuildings.
As part of your regular checks, gently remove cobwebs from around detectors using a duster or dry cloth. If a detector is in a hard-to-reach area, ask your alarm provider to check it during routine maintenance.
5. Pets moving around the property
Pets are another common cause of false alarms, especially if they are allowed to roam in areas protected by movement detectors.
Pet-sensitive detectors can help in some situations, but they are not a guarantee. False alarms can still occur if pets jump onto furniture, worktops, stairs or other raised surfaces.
To reduce the risk:
- Keep pets away from alarmed areas where possible
- Speak to your installer about pet-friendly detection options
- Review detector positions if pet-related false alarms continue
- You will need to ensure that pets are confined to either areas without detection or areas with ‘pet sensitive’ detection when the system is set or part set.
6. Dust on detector lenses
Dust can build up on detector lenses over time, especially after building work, decorating, sanding, plastering or refurbishment.
If you have recently had work carried out, check that detectors have not been covered in dust or disturbed.
You can gently clean the outside of a detector with a dry cloth or duster. Do not use water, sprays or chemicals on the detector.
7. Storms, wind and bad weather
Heavy rain, strong winds and storms can sometimes cause false alarms, particularly if they cause doors, windows, shutters or lightweight objects to move.
Weather-related false alarms may be caused by:
- A loose door or window moving in the wind
- A poorly fitted contact
- Objects moving inside the building
- Signs, decorations or blinds moving
- External detection affected by poor positioning or environmental factors
If false alarms happen during bad weather, it is worth having the system checked to identify whether a detector, contact or external area needs adjustment.
8. Decorations, signs or hanging items
Decorations and lightweight items can cause false alarms if they move near detectors.
This often happens with Christmas or Birthday decorations and balloons hanging in front of or near a detector that may move or flutter if there is a draft of air through the building.
Before setting the alarm, check that nothing is hanging in front of or close to a detector.
This is particularly important in shops, schools, offices, community buildings and commercial premises where displays may change regularly.
9. Heat sources near detectors
Movement detectors can be affected by changes in heat and movement within their detection area.
A new heat source installed near a detector could create false alarm issues. This may include:
- Radiators
- Heaters
- Fireplaces
- Air conditioning units
- Fans
- Warm air vents
- Portable heaters
If you are changing the layout of a room or installing new heating equipment, consider whether any detectors may need to be repositioned.
10. Obstructed detectors
False alarms can sometimes occur when detectors are blocked, partially covered or affected by stock, boxes, furniture or other items being moved around.
This is common in commercial premises where room layouts change or stock levels increase.
Make sure detectors are not:
- Covered
- Blocked by boxes or shelving
- Obstructed by furniture
- Facing moving objects
- Affected by stock being piled too close
- Accidentally knocked or moved
11. Window cleaners, contractors and visitors
False alarms can happen when window cleaners, contractors, cleaners or other visitors are working on site without knowing how the alarm system is set up.
For example, a window cleaner may trigger a shock detector while cleaning a window, or a contractor may enter an alarmed area without following the correct procedure.
To reduce the risk:
- Make sure contractors know when the alarm is set
- Tell regular contractors about any alarmed areas
- Provide clear instructions for authorised users
- Review cleaning or contractor access arrangements
12. User error
User error is one of the most common and avoidable causes of false alarms.
This can happen when a new colleague, family member, neighbour, cleaner or keyholder does not know how to operate the system correctly.
Common examples include:
- Entering or leaving by the wrong route
- Taking too long to unset the system
- Forgetting the alarm code
- Setting the wrong part-set area
- Opening a protected door after the system has been set
- Not checking that everyone has left the building
- Using an old or incorrect user code
Anyone who uses the alarm should understand the correct entry and exit procedure. It is also helpful to keep a quick user guide available for regular users and keyholders.
How to reduce false alarms
False alarms cannot always be avoided completely, but they can often be significantly reduced.
To help prevent false alarms:
- Have your alarm system serviced regularly
- Keep detectors clean and free from cobwebs
- Check doors and windows before setting the alarm
- Keep pets away from alarmed areas
- Remove insects before setting the system
- Keep decorations and hanging items away from detectors
- Make sure staff, family members and keyholders know how to use the system
- Report repeated false alarms to your alarm company
- Review your system if your building layout changes
When should you contact your alarm company?
You should contact your alarm provider if:
- False alarms happen repeatedly
- The same detector keeps activating
- You cannot identify the cause
- You have recently changed the layout of your building
- You have had building work or decorating carried out
- You have new pets in the property
- You have changed how the building is used
- You are worried your system is no longer suitable
A professional engineer can check whether the issue is caused by user error, environmental factors, equipment condition or system design.
MES Systems provides intruder alarm installation, servicing, maintenance and monitoring for homes and businesses across Nuneaton, Warwickshire and the wider Midlands.
Get in touch with MES Systems today to arrange an alarm service, maintenance visit or system review.
