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Intruder Alarm Systems - EN50131

Published 24/08/2012 11:00

From 1st October 2005 New European Standards for Intruder Alarms replaced British Standard 4737. These apply to all Intruder Alarm Systems to be installed to Domestic and Commercial premises alike.


Intruder Alarm Systems have to be security graded. The grading is dependant upon a risk assessment carried out by either the Alarm Company Surveyor or an Insurance Company Surveyor.

The System Design Proposal (Previously Specification) is to be based on a Risk Assessment

One of the fundamental differences between the current British Standards and the new EN standards is the way in which systems are to be designed.

EN standards require system designs to be based on RISK.

To aid this, intruder alarm systems installed in buildings are graded. The grade of system (please refer to next section) will take into account the:

  1. Risk level of the premises/house
  2. Risk level to the occupants (or householders) 
  3. Contents value
  4. Typical knowledge intruders might be expected to have

The risk assessment is a fundamental part of the survey, this will form the basis of the System Design ‘Proposal’.

It is therefore essential that all the risks are considered and that the system as designed is therefore suitable and adequate to protect the particular risks.

Grading of Systems and Grading of Equipment

System grades (1-4) are categorised within the EN standard as:

Grade 1 - Low risk system where intruders are expected to have little knowledge of intruder alarm systems and be restricted to a limited range of easily available tools. (This standard is less than the previous BS4737 and it is expected that grade 1 will not be acceptable to most Insurance Companies. E.g. certain devices are not required to be ‘tamper proof’)

Grade 2 - Low to medium risk system where intruders are expected to have a limited knowledge of intruder alarm systems and the use of a general range of tools and portable instruments.

Grade 3 - Medium to high-risk system where intruders are expected to be conversant with intruder alarm systems and have a comprehensive range of tools and portable electronic equipment.

Grade 4 - High-risk system where security takes precedence over all other factors. Intruders are expected to have the ability or recourse to plan an intrusion in detail and have a full range of equipment, including means of substitution and vital components in the intruder alarm system.

Additional Items

The equipment is now graded according to the level of protection built into the device, with grade 1 being the lowest (least secure) security grade. 12 hours of standby battery power is now mandatory (BS4737 was 8 hours). Control Panels are to have considerably more ‘reporting information’ e.g. for greater event recording and memory

Environmental Classification of Equipment:

As well as the 4 security grades, the equipment now has to conform to one of 4 environmental classes:

Class 1 – Indoor (Even temperature) (e.g. office / living room)

Class 2 – Indoor General (e.g. Garage)

Class 3 – Outdoor Sheltered

Class 4 – Outdoor General (Open to the elements etc)  

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