Clarion Security Systems

Intruder Alarm Grades

One of the most important aspects of the EN 50131 requirements is the concept of a security grade. For each installation the grade of system has to be chosen according to various factors. In the EN the grade is described in terms of the type of intruder and how much effort they would put into a burglary.

What are the Grades?

Grade 1 is for an installation with a low risk of theft. The property is not likely to attract intruders. It is assumed that a thief is likely to be opportunistic rather than bothering to plan things in advance. In the application guide (DD CLC/TS 50131-7) it assumes that an intruder is simply going to break open a door.

Grade 2 is for a slightly higher risk of theft. The property is likely to have something of interest to an experienced thief. In this case the intruder is expected to have some knowledge of how alarm systems work and possibly carry some tools to allow him to overcome a simple alarm system. The thief is likely to check the building for ease of access through doors, windows and other openings.

Grade 3 is for a reasonably substantial risk property. There is good reason to assume it may be broken into and might well contain objects of high value. An intruder is likely to gain access by penetrating doors, windows or other openings. The thief could be very experienced with intruder alarm systems and possess a number of tools and equipment to overcome the system

Grade 4 is for very high-risk properties. Intruders could be expected to plan a burglary in advance and have the knowledge and equipment to alter parts of the intruder alarm system to prevent detection. It is assumed that the intruder could gain access by penetration of floors, walls and ceilings. The intruder is unlikely to be working alone.
The EN standard says that it is not necessary to use the same grade of component throughout an intruder system.

What type of graded system does my install need?

The type of system will depend entirely on a site survey and risk assessment of the premises in question. Intruder alarm installers will perform risk assessment so that the risk associated to the premises can be fully understood this will then determine the correct grading.

  • Grade 1 would only be of interest in domestic properties (without an insurance requirement for an alarm system).
  • Grade 2 would be most domestic properties and low risk commercial (e.g. florists)
  • Grade 3 would be for high-risk domestics and most commercial properties (e.g. Newsagent with cigarette sales)
  • Grade 4 would be for extremely high-risk domestic and higher risk commercial properties (e.g. bullion stores)

If the installation is a grade 2 then there is no problem using, for example, a grade 3 power supply.

If however an installer fits a grade 2 component (such as a detector) in a system then that system is limited to grade 2 at best.

What Maintenance is Required?
Routine maintenance requirements typically involve one check per annum for Audible Only systems, and two checks per annum for ARC monitored systems, one of which can be a remote check – subject to equipment compatibility. Find out more about our maintenance here.

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