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Intruder Alarms - Avoiding False Alarms [Hardfacts]


The main purpose of an intruder alarm is to raise an appropriate human response after any activation or critical fault.

That response can come locally via the provision of a site warning device (sounder) intended to alert staff, neighbours or friends who may be working/residing at or adjacent to the alarm protected premises or, more usually, remotely via a suitable signal being sent to an Alarm Receiving Centre (ARC), who will then contact nominated keyholders and, for suitably registered systems which generate a Qualifying Activation, the police.

Note. UK police forces will provide a response to intruder alarm activations only where the system, and the ARC that monitors it, complies with a formal set of police rules – either the National Police Chiefs’ Council (NPCC) rules in England, Wales and N Ireland or the Police Scotland rules in Scotland. See ‘Hardfacts’ 3008: Police Response to Security Systems for more details.

In the spirit of the story about ‘the boy who cried wolf’ it is very important to maintain the credibility of your alarm system by avoiding false alarms.

The Need to Avoid False Alarms

Avoiding false alarms is clearly important to avoid inconvenience to those expected/tasked with responding, but assumes greater significance where an alarm system has a police Unique Reference Number (URN), and is thus eligible for police response. This is because such systems are required to not exceed a set threshold of false alarms over a rolling 12 month period, as outlined in the relevant police forces Security System Policy (SSP).

These false alarm thresholds are shown below, together with the police sanctions that follow if they are breached:

NPCC Forces
- 3 false intruder or 2 false Hold Up Alarm (HUA) calls and response is withdrawn.

Police Scotland Forces
- 4 false intruder or HUA calls and response moves to Level 2.
- 3 further calls and response is withdrawn.

Note. The police response levels referred to above are:

  •      Level 1 – An Immediate/Priority Response.
  •      Level 2^ – Police response is desirable, but attendance may be delayed.
  •      Level 3 – No police attendance, i.e. response has been formally withdrawn.

^Level 2 is no longer provide by most NPCC forces.

The Consequences of False Alarms

Where you are relying solely upon a local response to alarm activations, too many false alarms can easily lead to those expected to respond becoming immune to the call for help; and at worst this can lead to a complaint being made to the Local Authority about the nuisance caused by an alarm, which in turn can lead to legal enforcement action against you.

With tight false alarm thresholds now being applied by the police, systems with police response can very quickly find it downgraded or lost. If this occurs, alarm users may face considerable cost and inconvenience associated with:

  • Providing a premises guard/commercial response service in place of police.
  • Revising safety arrangements for staff keyholders attending alarm activation's without the police, e.g. ensuring they attend in pairs or with a commercial response company.
  • Upgrading older non-confirmation system to become able to provide ‘confirmed activations’. See ‘Hardfacts’ 3022: Intruder alarms – Confirmation Systems for more information.
  • Upgrading HUA facilities to include confirmation (Intervention) technology/procedures.
  •  Insurers withdrawing insurance cover or applying restrictions whilst the situation is resolved.

Common Causes of False Alarms

False alarms will generally relate to environmental factors affecting alarm equipment, or the actions/omissions of users. In most cases these causes can be readily avoided if system users have sufficient information/training to be able to identify possible problems in advance and an adequate understanding as to how the alarm system works.

A list of typical false alarm causes and related remedial actions is provided below. It may be helpful to print this out and either give it to alarm users or display it by alarm setting points.

Causes of False Alarms – Equipment related
Attention to the matters outlined below can help reduce the risk of false alarms related to equipment:

  • Damage to Alarm Equipment - Alarm sensors or cables prone to damage by moving vehicles or objects should be protected by cages or cable conduit, or otherwise be relocated. 
  • Detectors/Sensors Loose - All detection devices should be securely mounted.
  • Dirty Movement Sensors - Sensors should be kept clean, as dirt both impairs detection ability and encourages spiders and other insects to reside in, on or around them. 
  • Doors/Windows - Poorly maintained or loose windows and doors may move and activate sensors
  • Changed Environments - Installation of new doors, windows, heaters or machinery/plant – especially those that may switch on or be left operating when the alarm is set, can create heat sources that may activate movement sensors.
  • Sensors Obscured - Installing new signs (especially hanging ones), racking or partitions may reduce sensor range or create the risk of false alarms.
  •  Inappropriate Sensors Installed - Sensors need to be carefully selected e.g. installing vibration sensors to doors or windows adjacent to a busy road is very likely to result in false alarms.
  • Hold Up Buttons - These should not be installed on personnel traffic routes, i.e. where they may be bumped into and inadvertently operated, and should also be of a ‘twin button’ type to prevent accidental operation.

Causes of False Alarms – User related

Attention to the matters outlined below can help reduce the risk of false alarms related to users:

  • Training to operate the system - Alarm system users should understand how the system works and in particular how to deal with any problems encountered. Periodic refresher training is advisable.
  • Training in the use of HUA facilities – This is critical, as police have a very strict interpretation of what constitutes legitimate use, i.e. an immediate attack or threat of one involving personnel at the alarm protected premises. This means, for example, that HUA facilities should not be used in relation to events that have concluded or where staff may view events occurring outside, e.g. a street fight or robbery. In such circumstances, telephoning for police assistance is the expected course of action.
  •  User Codes/Fobs - The use of individual rather than shared alarm codes, or specific allocated operating ‘fobs’, allows ‘problem’ users to be identified from the control panel log and, if required, re-trained.
  • Testing Movement Sensors - Most movement sensors contain indicator lights, enabling users to walk through the area of coverage and check that they are operating correctly. This should be done regularly.
  • Keys to the Premises - Only trained alarm users should have keys to the premises.
  • Entry/Exit Route - Keep to a minimum the number of alarm unsetting/setting points.
  • Locking Up Procedure - Before setting an alarm the premises should be checked to ensure that no one is inside, any movement sensors are unobstructed, no temporary heaters have been left on and that all doors and windows are closed and secure.
  • Opening Up Procedure - Ensure nobody enters the rest of premises, i.e. departs from the designated Entry/Exit route, until the alarm is fully un-set.
  • Access to Telephones - Should users need to urgently contact the ARC e.g. to cancel a false alarm, they need access to a phone by the alarm control panel or keypad.

Key Action Steps

  •  Check your current false alarm record and police response status with your alarm company.
  •  Adopt measures to avoid false alarms, and ensure that if they do occur prompt and thorough steps are taken to resolve any problem.
  •  Ensure alarm users understand the need to properly secure and check premises for potential problems before leaving
  •  Ensure alarm users understand the correct operation of the alarm system.
  • Where insurance cover is conditional upon an alarm receiving police response, ensure that insurers are notified of response being downgraded or lost; noting that it is likely that they will wish to discuss and agree any proposed changes to your alarm system – in particular any change to provide confirmed activations, and may also wish to discuss and agree any proposed temporary, or longer term, alternative security measures.

Sources of Further Information
Other Hardfacts in the Property Protection - Security Series, which are available in our
‘Knowledge Store’ at

Your intruder alarm company
The National Security Inspectorate (NSI) - Tel 0845 006 3003 or
The Security Systems and Alarms Inspection Board (SSAIB) - Tel 0191 296 3242 or  
The British Security Industry Association (BSIA). Tel 0845 389 3889 or see

Next Steps:

  • Source discounted products, available to Aviva insured customers and brokers only, via our Specialist Partners - click here to find out more about the savings you could make
  • View our Tools and Templates
  • Call our Risk Helpline on 0345 366 66 66
  •  Email us at

Please Note
This document contains general information and guidance and is not and should not be relied on as specific advice. The document may not cover every risk, exposure or hazard that may arise and Aviva recommend that you obtain specific advice relevant to the circumstances. AVIVA accepts no responsibility or liability towards any person who may rely upon this document.

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