Intruders are expected to have little knowledge of the system and may be restricted to a limited range of easily available tools Grade 1 is for a low risk of theft. It applies to a property which is not likely to attract burglars. In the application guide (DC CLC/TS 50131-7), it assumes that a thief is likely to be opportunistic rather than planning a theft and will simply break open a door.
Intruders are expected to have a little more knowledge of the system and use a general range of tools and some specialist equipment. Grade 2 is for a higher risk of theft. Such a property is likely to have something of interest to an experienced thief who is likely to have some knowledge of how your systems work and possibly carry some tools to help him overcome a simple home alarm system. The thief is likely to check the building for easy access through doors, windows and other openings, therefore these are the principle areas of detection.
Intruders are expected to be conversant with the system and have a comprehensive range of tools and portable electronic equipment.. Grade 3 is for a property. which is a reasonably substantial risk, one which, might well contain objects of high value so there is good reason to assume it may be broken into. An intruder is likely to be knowledgeable about intruder alarm-systems and may attempt to overcome the system. The thief is likely to get in by penetrating doors, windows or other openings but can also be expected to gain access by penetration of floors, walls and ceilings so additional protection is required.
To be used when security takes precedence over all other factors. Intruders are expected to have the resources to plan an intrusion in detail and have a full range of equipment, including the means to substitute vial components in the system.. Grade 4 is for highest-risk properties. Such properties are likely to be targeted by a gang of thieves who will probably have planned the burglary in advance. They will know some techniques for preventing detection or tampering with burglar alarm systems, and therefore, the levels of sophistication need to be that much greater to prevent this happening.