Intruder alert

The professional electrical contractor has always had a measured interest in intruder alarms and the documents that relate to them. With the influence of the recently introduced EN 50131 becoming very much apparent, a basic overview of this range of European Standards can help firms keep abreast with new assessment methods.

The withdrawal of the traditional BS 4737 and the introduction of the EN 50131 suite of standards introduced a rather different approach to the way in which the UK intruder alarm industry was to be governed. It meant that the particular security grades for the installation were to be in relation to the risk faced and determined by the installer through risk assessment.

In effect, the engineer had to be trained to assess risks in a much more formal capacity than that demanded of the original generation British Standard.

There is no particular method for conducting a risk assessment, but it is necessary to ensure that all risks are considered and a system designed to protect them. It is worth noting that the EN 50131 application guidelines state that all persons responsible for the risk assessment and the design, installation, maintenance and repair of intruder alarm systems should hold appropriate qualifications. Although there’s no defined and agreed qualifications structure, it clearly means that all parties must be capable of demonstrating competence.

It should also be appreciated that a specification known as PD 6662 was introduced in the UK as a ‘wrapper document’ because, although BS 4737 had to be withdrawn under the European agreement, not all of the EN 50131 documents were completed at the introduction date. For this reason, a parallel interim running period needed to be implemented.

Risk assessment

To establish the level of risk and subsequent security grade for the premises to be protected, the installation company needs to consider different criteria involving:

• location;
• contents;
• building design;
• minimum supervision levels of the detection devices required.

Evaluation of the need must be carried out in a structured format. A simple industry technique is the ABC of risk, where:

A = area;

B = boundaries/buildings;

C = contents.

The equipment and components for installation in the intruder sector must actually be declared as compliant to a particular EN grade by the manufacturer or distributor.

This means the electrician must then select appropriate manufacturers’ graded parts that correspond to and suit the grade for the supervised premises determined at the time of the risk assessment. In terms of the main detection wiring techniques, these make up the most comprehensive part of the installation with Grade 2 non-communicating the most practised.

It’s important not to forget that regular preventative maintenance is mandatory at every grade and, although different approval Inspectorates may have their own criteria, there is an industry policy. The 2004 Code of Practice stipulates that Grades 1 and 2X should receive a site visit each year. Grades 2 and 3 should either be visited twice a year, or receive one site inspection and one remote system check per year. Grade 4 warrants two site visits per year.

A full description of risk assessment guidance is given in the UK document: DD CLC/TS 50131-7:2003 Intruder Alarm Systems – application guidelines.