NEWS

The emphasis on technical excellence in the cabling industry has never been greater with the increasing demands of legislation and standards. Technical Director of AEI Cables Bill Davis takes a look at the issues.

Cable design and performance standards are becoming increasingly demanding and are driven by changes in building standards, health and safety legislation, environmental mandates and liability issues.

Additionally, “systems” are becoming much more complex and there is a growing dependence on integrated systems to provide expanded services to satisfy public and industry expectations.

As requirements increase, the design and performance of electrical and electronic cable can no longer be taken for granted. Electrical cable plays a significant role in any system and must stand up to conditions that were unthinkable in the past. This is particularly true with respect to fire performance where cabling systems must continue to perform in extreme fire situations.

Cable materials used for insulating, filling, and sheathing are fundamental to a cable’s performance and its ability to survive in demanding environments.

Whether it is fire performance, environmental conditions, volatile chemical attack, UV exposure, radiation, or other hostile conditions, the selection of appropriate cable materials is critically important.

No longer can a cable manufacturer depend on “off the shelf” generic compounds to satisfy the needs of a demanding application.

Instead, custom engineered polymeric compounds are frequently required to achieve challenging performance characteristics. As polymer science and materials technology take on greater importance in the cable industry, the development of in-house facilities becomes more important.

Indeed, strict regimes throughout the manufacturing process are fundamental to ensuring that the products meet and exceed needs.

In these days of increasing compliance requirements, neither the manufacturer, the specifier or the contractor want any issues which lead to stoppages and loss of time.

For all of these reasons, weighing the risk of safety in fire performance is becoming a major issue.

Critical control systems require secure power supplies, perhaps for the duration of a major fire. These systems will be used for safety and security and often for building monitoring, providing intelligence on a range of subjects, with phased evacuation where relevant.

The only way to assess the most appropriate products and systems for each project is to consider the specific requirements of each on a case-by-case basis.

To be in a position to make informed decisions, however, we should be aware of all the options available and what is most appropriate.

Functional safety relies on the overall safety that in turn depends on a system or equipment operating correctly in response to installation.

The revised BS 5839-1 (02) for fire detection and alarm equipment includes the requirement that cables for addressable alarms must be - and remain - data compatible.

Data integrity requirements are becoming increasingly important as fire safety systems become more intelligent and integrated. Many of today’s modern commercial buildings incorporate fire detection, intrusion alarms, environmental controls, heat, lighting, and energy management all in a single system or in stand alone systems that communicate shared data for a co-ordinated response to an alarm situation.

As a result, data transmission is a critical parameter in the selection of cable and much more so in fire performance applications.

Where there is a need for critical data links to function in a fire situation, mineral cable is the only acceptable choice.

It is recognised as the cable of choice for fire alarms, detection equipment and emergency lighting and the risk of anything going wrong is greatly reduced because of its key features.

It has the ability to withstand temperatures over 1,000 degrees centigrade, can continue data transmission during a real fire and there is reduced need for maintenance.

Where risk assessments have been completed and all involved parties agree, an enhanced cable with a lower survival capability than a mineral insulated product can be installed in that particular specific application.

These products are designed for fire performance qualities which are flame retardant, robust and meeting the higher end requirements in BS 5839-1 (02).

Where the project can be served with softskin cables which meet the desired criteria of for standard applications, and a risk assessment has been completed involving all parties, then standard cabling is the ideal choice.

There are many products now available in the fire performance sector and the sheer number and choice can make the selection process difficult, especially with so much legislative change.

Ultimately, it is down to each organisation and each person in the supply chain to meet their relative responsibilities and know they are not compromising the safety of others.

With expert help and guidance, they can make considered judgements during the selection process, knowing they have made the correct choice without compromising the relevant standards and regulations.

Bill Davis is Technical Director of AEI Cables Limited. Contact: AEI Cables Limited, Chester-le-Street, Co. Durham DH3 2RA, Tel: 0191 410 3111, Fax: 0191 410 8312, E-mail: info@aeicables.co.uk