The major differences between EN 50131 and BS 4737 are:

• Structured standards
• Grading of systems
• Classification of equipment
• Risk based

This provides a structured approach to:

• Assessment of risk
• Technical survey
• System design
• Installation of the system in accordance with agreed specification
• Installation of equipment in accordance with manufacturers recommendations

A significant advantage for insurers and surveyors applying European Standards to systems is the specification of grades appropriate to the associated Risk. One of the major differences in the European Standards is the grading of systems, which is not a feature of BS 4737.

The grading of a system based on a structured risk analysis will determine the:

• Extent of the system
• Signalling
• Tamper security

Within the new European Standards there are four security grades:

• Grade 1 - low risk
• Grade 2 - low to medium risk
• Grade 3 - medium to high risk
• Grade 4 - high risk

For a Grade 1 system intruders are expected to have little knowledge of intruder alarm systems and be limited to a range of easily available tools.

A Grade 2 system expects intruders to have a limited knowledge of intruder alarm systems and the use of a general range of tools.

A Grade 3 system expects intruders to be conversant with intruder alarm systems and have access to a comprehensive range of tools.

Finally, a Grade 4 system is where security takes precedence over all other factors. At this level intruders are expected to have the ability and resources to plan an intrusion in detail and have a full range of specialised equipment, including means of substitution of vital components within the intruder alarm system. As you can see systems are evaluated against the risk of the level of intruder that may attack the system hence the requirement that system design meets the appropriate grade.

The will be defined by a security surveyor, customer or insurers. It is most likely that insurers will specify systems at Grades 3 and 4.

A further inclusion in European Standards is the classification of components that are used for the intruder alarm system installations. These will be classified, which in turn will determine where they are installed. There are four classifications of components:

• Class 1 = Indoors controlled temperature
• Class 2 = Indoors uncontrolled
• Class 3 = Outdoors sheltered
• Class 4 = Outdoors exposed

System specifications, as we currently refer to them, will in European Standards terms be known as the System Design Proposal and will propose the optimum system available by the installing company.

As systems will be graded the number of maintenance visits will vary. Depending on the grade of system the number of maintenance visits will be:

• Grade 1 - 1 site visit per annum
• Grade 2X - 1 site visit per annum
• Grades 2 & 3 - 2 site visits per annum OR

1 site visit plus 1 remote

• Grade 4 - 2 site visits per annum

Power Supply Standby Requirements

The table shows power supply requirements for the grade of system. Type A and B power supplies refer to the standby power type; Type A are mains and rechargeable batteries, and Type B are mains and non-rechargeable batteries.

* For Grade 3 systems under the latest revision of the standards, the 24 hour battery standby time can be reduced to 12 hours if the control and indicating equipment is capable of sending a "mains fail" to the Alarms Receiving Centre.