Fire performance cable to BS 7629-1 is a screened, low smoke zero halogen cable designed to keep a circuit working while a building burns. The insulation is a cross-linked or silicone rubber compound that chars rather than melts, an aluminium/polyester laminate screen with a tinned copper contact wire provides the circuit protective conductor and electrical screening, and the LSZH sheath keeps smoke and corrosive gas emission low. It comes in standard grade, which survives 30 minutes of fire testing, and enhanced grade, which survives 120 minutes.
Key applications
- Fire alarm and detection circuits to BS 5839
- Voice alarm and public address systems
- Emergency lighting control and monitoring circuits
- Sprinkler and smoke control system wiring
- Firefighters' lift and wet riser control circuits
- Life safety wiring in escape routes and protected shafts
Features and benefits
- Maintains circuit integrity under direct flame, water spray and mechanical shock
- Low smoke, zero halogen sheath reduces smoke obscuration and corrosive gas
- Screen doubles as the circuit protective conductor, so no separate CPC run is needed
- Solid conductors terminate cleanly without ferrules
- Red or white sheath identifies the circuit function at a glance
Specification notes and limitations
Standard grade and enhanced grade are not interchangeable: BS 5839-1 requires enhanced grade in defined circumstances, including larger phased-evacuation buildings and unsprinklered premises, and specifying standard grade in those positions is a design failure, not a cost saving. The minimum bending radius is six times the overall diameter and must be respected — a crushed or sharply bent cable loses its fire performance even though it still tests electrically. Fire rated cable must be supported by metallic fixings along its whole route, because plastic clips and ties fail early in a fire and the cable then falls and shorts, defeating the point of specifying it. Do not install below 0°C, and make the screen off properly at every termination so the CPC remains continuous.
