Intruder and vehicle alarms

Advice about alarm installations

If you already have an alarm or you are thinking about installing one, there are some things that you need to know.

Alarms are fitted to many vehicles and properties either for reasons of personal security or as an insurance company requirement. Nowadays with premises alarms the old bell type alarm has generally been replaced with far more sophisticated systems that can be split into two categories.

Monitored systems

  • Those that automatically advise a security company that the alarm has been activated.
  • These systems rarely cause noise problems as the security company is able to deal with the incident and silence the alarm.

Audible only systems

  • Those that, if activated, produce an audible sound only.
  • Unfortunately, if these systems misfire and cannot be turned off or the 20 minute cut out fails to operate the noise is intrusive and causes disturbance and nuisance.
  • Vehicle alarms come in many different types, some factory fitted, some fitted as after-market equipment.
  • In a similar manner to premises alarms vehicles should be fitted with a cut-off which ensures they do not sound for more than three minutes to avoid causing a nuisance.

Twenty minute alarm cut-off time

If an alarm continues to misfire and causes a nuisance then the Environmental Protection Act 1990 gives the council powers to serve notice, enter your property or vehicle and silence and make safe the alarm that is causing a nuisance.

If this happens, you will have to pay the council’s expenses for silencing the alarm in your absence (this could be hundreds of pounds) and possibly be fined for causing a nuisance. In addition, with a misfiring vehicle alarm the offending vehicle may be towed away to a place of safety because the security system has had to be disabled by the council's contractors, this will increase the costs.

How to avoid having to pay for the silencing of your alarm

  • Make sure the alarm is properly installed and regularly maintained.
  • Make sure the alarm is fitted with a cut-off device that stops the alarm if it misfires
  • Notify premises alarms to the police contact details:
    Alarms Administration, Thames Valley Police HQ, Oxford Road, Kidlington, Oxfordshire, OX5 2NX
    Telephone 01865 846489 or email Thames Valley Police
  • Fill in the intruder alarm notification form for the police and the council, to register the alarm and provide details of two keyholders who can quickly silence the alarm in your absence. 
  • Remember Environmental Health deals with approximately 150 misfiring alarms each year and, "it could be you".

Installation and existing systems

Although intruder alarm systems should be installed according to British Standard 4737: Specification for Intruder Alarm Systems in Buildings many 'false alarms' are caused by faulty installation, poor maintenance and incorrect use of the alarm. It is advised to install the alarm properly yourself or by getting a National Approval Council Security Systems (NACOSS) or a Security Systems and Alarms Inspection Board (SSAIB) approved company to do it. Check with your insurance company to see if they have any special requirements.

Some classic examples of causes of misfiring alarms Environmental Health have had to deal with include:

  • Power cuts
  • Spiders in the sensors
  • Pets roaming round the house
  • People not knowing how to turn the alarm off
  • Wind or hot sunshine setting off car alarms

If you take over an existing system make sure that:

  • It is installed correctly and working properly
  • It has a cut out device
  • For premises alarms, that the police are aware of your keyholders and the previous keyholders are removed from their records
  • You register any premises alarm with your details

Cut-out devices

  • All current premises alarms should now be installed with a device that stops the alarm sounding after 20 minutes.
  • Also a flashing light that continues after the alarm has stopped sounding may be fitted to assist in identifying the property or act as a warning that the alarm has been activated even if the bell or siren is now silent.
  • Many premises alarm installers now offer a monitoring service with the system.
  • This means that if the alarm is activated a call will be made to a 24 hour manned listening station and the police will automatically be notified, of course, it is still critical to ensure that you have keyholders who can attend and silence the system.


  • These should be local and ideally be able to attend the premises within 20 minutes, should know how to turn off the alarm and be able to help the police if your property has been burgled.
  • If for any reason you change your nominated keyholders, you should notify the police within 24 hours.

Environmental Health contact information

Postal address:, Civic, 1 Saxon Gate East, Milton Keynes MK9 3EJ