Why are fire resistant cables needed?

UK building regulations make it clear that buildings need a risk assessment conducted early in the design stages to assess the fire risk to people and property. For public buildings this commonly results in the need for fire detection, fire alarms and emergency lighting systems.

There may also be a need for life safety and fire-fighting systems and each of these emergency systems need to maintain circuit integrity during the fire. In such circumstances, only fire resistant cables can do this.

Prysmian fire resistant cables have been produced for almost 50 years and the company is proud to be still leading the development of fire performance cables. Not only can they help save lives in a fire, but they also provide greater property protection. Prysmian have an extensive range of fire resistant cables, that are all independently assessed and certified by BASEC and LPCB to ensure that they are fully compliant with British Standards.

A brief introduction to British Standards

The British Standard Institution (BSI) is a private company incorporated by Royal Charter and publishes British Standards for a wide range of uses underlined by their principle to ‘make excellence a habit’.

The standards, written by experts in their field, are designed for voluntary use. Although they are not law, British Standards are an agreed current best practice which can provide the basis for contract and can improve safety.

British Standards that involve fire resistant cables fall into three categories:

1. Applications Standards – Codes of Practice for applications that need fire resistant cables
2. Construction Standards – Specifications for manufacturing fire resistant cables
3. Test Standards – Procedures for testing fire resistant cables

It is worth noting that new and existing British Standards that involve fire resistant cables continue to be major discussion points amongst clients, consultants and installers.

BS 5839-1

The full title is, ‘BS 5839-1: Fire detection and fire alarm systems for buildings. Code of practice for design, installation, commissioning, and maintenance of systems in non- domestic premises’; it provides considerations and some specific criteria for the lifetime of the system, from inception to operation.

For cables, it specifies the fire performance required of ‘standard’ and ‘enhanced’ fire resistant cables. It also recommends criteria of the building design that helps the designer to select the cable type e.g., the number of evacuation phases or the level of sprinkler coverage. The code of practice recommends a number of details, for example the preferred sheath colour of the cable, cable fixing methods and segregation from other services. It also includes a normative list of associated British Standards which helps designers and installers alike.

In terms of our fire performance cables, Prysmian FP200 GOLD is the most prevalent ‘standard’ fire resistant cable solution for fire detection and fire alarms, which features both fire resistant and flame retardant properties. It exceeds the minimum 30 minutes survival time in flame and impact tests, plus an additional requirement for fire and water spray. In addition, FP200 Gold retains its well-earned reputation as easy to install and terminate on site.

FP PLUS meets the requirements for an ‘enhanced’ fire resistance cable which uses the enhanced Insudite. With its hard skin, FP PLUS is the ideal choice for fire alarm and emergency lighting systems typically for large and complex buildings especially hospitals. It is also used for emergency voice communications, escape lighting, and other control circuits for fire safety.

BS 8519

The full title is ‘BS 8519: Selection and installation of fire resistant power and control cable systems for life safety and fire-fighting applications code of practice. The code defines the requirements for fire resistance and a set of performance criteria for cables: Category 1, 2 and 3 for power cables and the same  for control cables. Life safety and fire fighting systems are different from the Fire Alarm and Emergency Lighting British Standards which detail the performance of evacuation systems, BS 8519 recommends fire performance requirements for cables that power and control systems that can assist the fire and rescue teams that deliberately enter the building for long after occupants have evacuated.

Electrical life safety applications include smoke and heat exhaust ventilation systems designed to manage deadly quantities of smoke and very hot toxic gases to protect people still in the building. Life safety systems include communication links to occupied areas that may have to remain populated as part of the fire strategy, for example intensive care wards in hospitals or disabled refuges in high rise buildings.

BS 8519 addresses cable performance of fire-fighting applications for fire fighters to take control of the fire. For example, sprinkler pump power and control circuits, also power and control of fire-fighting lifts used by the fire-fighters to move around in large and complex buildings. The code also helps designers select the appropriate cable for systems that prolong life and fight fire.

Our ultimate fire resistant, armoured cable Prysmian FP600s meets the highest criteria of the British Standard (Cat 3, power). FP600s is designed to power life safety and fire-fighting systems used in buildings. Its applications also include powering smoke barriers, smoke and heat exhaust ventilation systems, and extinguishing systems such as sprinkler pumps.

FP cables are critical in helping to protect lives and property. Their design makes them an essential asset in public buildings.

Learn more about the components that make fire resistant cables in our next blog…

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