Fire Detection

Dr Jeremy Hodge, chief executive of the British Approvals Service for Cables (BASEC) discusses fire detection.

Focus on low smoke cables

More people are specifying and using low smoke halogen free (LSHF) cables. There are four main types:

• Large power cables to BS 6724. Used where loss of human life and material assets must be prevented, e.g. in industrial plant, multi-storey buildings, airports and tunnels.

• Small wiring cables to BS7211. Used where smoke and toxic emissions pose a hazard in the event of a fire in domestic and commercial environments. Enclosed in trunking or conduit where mechanical protection is required.

• Fire protection cables to BS 5839-1. Used in fire alarm and other emergency systems.

• Flexible cables to HD 21.14. Used where flexibility and LSHF performance is needed, such as commercial lighting.

Fire resisting cables

Fire safety engineering techniques permit a more open building structure and ensures safe evacuation in the event of a fire by a combination of traditional and modern, active fire systems. Many of these systems require electrical power supplies and control circuitry to remain functional throughout a potentially serious fire. Examples include fire-fighting lifts and smoke extraction systems. Robust fire resistant cables are needed here to continue to work in a fire. For this you need special fire resistant cables such as BS 7846 armoured cable or mineral cable to IEC 60702-1. These fire resistant cables can also be described as LSHF as they use the appropriate materials (optional oversheath for mineral cables), but they have additional construction features to provide circuit integrity throughout a fire.

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