Fire Retardant Fibreglass Cable Tray 100mm-1200mm Width GB8624 for Metro Tunnels

Fire Retardant Fibreglass Cable Tray For Tunnels Or Metro

BENDIN Fire retardant fibreglass cable trays achieve their flame-resistant properties through a carefully engineered composite formulation that combines glass fibre reinforcement with specialised thermoset resins and flame-retardant additives. The pultrusion process embeds continuous glass fibre rovings in a resin matrix containing brominated or phosphorus-based flame retardants, along with hydrated mineral fillers such as aluminium trihydrate that release water vapour when exposed to heat, cooling the material and diluting combustible gases. This formulation produces a material with an oxygen index of 26 or higher, classifying it as B1 grade flame retardant, and self-extinguishing performance rated to UL 94 V0, meaning the material stops burning within seconds after the ignition source is removed. The absence of halogens in the resin system means that in the event of a fire, the tray does not release toxic or corrosive fumes—a critical safety requirement in enclosed tunnel environments where evacuation and firefighting operations are severely constrained. Fire propagation testing to BS 476 Part 6 and spread of flame classification to BS 476 Part 7 Class 1 or 2 further validate the material's performance under realistic fire conditions, while smoke emission testing to BS 6853 confirms low smoke density that preserves visibility during emergency egress.

In tunnels and metro systems, the functional role of fire retardant fibreglass cable trays extends far beyond simple cable support. These enclosed environments present a unique combination of challenges: high humidity from groundwater infiltration, limited ventilation, restricted access for maintenance, and the presence of thousands of passengers who must be protected in the event of an emergency. Fibreglass trays address these challenges through their complete immunity to corrosion—the material does not rust or degrade in the presence of moisture, salt-laden air, or chemical runoff, eliminating the maintenance burden that plagues steel trays in tunnel installations. The lightweight nature of fibreglass, approximately 40% lighter than steel of equivalent capacity, facilitates installation in the confined spaces of tunnel ceilings and cable galleries where heavy lifting equipment cannot be deployed. Critically, the non-conductive and anti-magnetic properties of fibreglass mean the tray does not interfere with signalling circuits, electromagnetic pulses, or traction power systems, and no earthing is required—a significant advantage in metro environments where electrical isolation is paramount. The material maintains full structural integrity across a temperature range of −80°C to +130°C, ensuring reliable performance in both the cold drafts of tunnel ventilation shafts and the heat generated by train operations.

Certification requirements for fire retardant fibreglass cable trays in tunnels and metro systems are among the most stringent of any application, reflecting the high life-safety stakes involved. In North America, NFPA 130—the Standard for Fixed Guideway Transit and Passenger Rail Systems—governs fire safety requirements for underground stations and trainways, addressing cable flame spread, smoke release, and structural component fire performance tested per ASTM E162 and ASTM E662. Cable trays installed in these environments must demonstrate compliance with NEMA FG 1 for fibreglass tray systems and ANSI/UL 568 for non-metallic trays, with fire performance verified to ASTM E84 Class 1 flame spread. In the United Kingdom and Commonwealth countries, BS 6853 is the definitive standard for fire performance of materials in railway vehicles and infrastructure, with Category 1B requirements for smoke emission and toxicity being commonly specified for tunnel installations; London Underground maintains its own Products Register that lists approved cable management systems meeting its specific fire safety criteria. European projects typically reference EN 13501-1 for reaction-to-fire classification, alongside BS 476 Parts 6 and 7 for fire propagation and surface spread of flame, and DIN 4102 Part 12 for fire resistance of cable systems. The French M1 classification under NF P 92-501 is also widely cited for tunnel projects, with M1 representing the highest fire performance rating for building materials. In the Middle East, metro projects in Dubai, Riyadh, and Doha commonly reference NFPA 130, BS 6853, and IEC 61537, while in the Asia-Pacific region, projects reference GB 8624 in China, AS/NZS 1530 in Australia, and IEC 60332 for cable fire testing alongside the relevant national building codes.

BENDIN Fire retardant fibreglass cable trays for tunnel and metro applications are available in ladder, perforated, solid-bottom, and trough configurations, with the choice determined by cable type, ventilation requirements, and protection needs. Ladder-type trays are preferred for power cable runs where heat dissipation is critical, while solid-bottom trough trays with covers provide maximum protection for communication and signalling cables in areas subject to water ingress or dust accumulation. Standard fibreglass cable tray widths range from 50 mm to 1,000 mm, with common side rail heights of 50 mm to 150 mm, wall thicknesses of 3 mm to 6 mm, and standard section lengths of 3,000 mm or 6,000 mm. Pressed GRP trays typically range from 50 × 50 mm to 400 × 80 mm, while pultruded GRP cable ladders span from 200 × 53 mm to 900 × 150 mm, with load characteristics verified in accordance with IEC 61537. The load capacity of a given tray depends on the support span and side rail height, with typical safe working loads of 70 kg/m to 150 kg/m under IEC 61537 testing. For tunnel applications, cable fill ratios should not exceed 40–50% for power cables and 50–70% for control and communication cables, with temperature derating applied for ambient conditions exceeding 75°F (24°C). The table below summarises the principal certification requirements and commonly specified dimensions for fire retardant fibreglass cable trays across major global tunnel and metro markets.

Installation of fire retardant fibreglass cable trays in tunnels and metro systems requires careful attention to support spacing, thermal movement, cable segregation, and fire stopping. Support spacing should be determined by the load class and the manufacturer's load-deflection curves, with typical horizontal intervals of 1.5 m to 3 m in tunnel installations and shorter spans in areas subject to vibration from train operations. An 8 mm expansion gap must be provided at each coupler to accommodate thermal movement, and expansion splice plates should be installed at calculated intervals to prevent buckling or joint separation in long straight runs. The tray should be anchored at the support nearest the midpoint between expansion joints to allow controlled movement in both directions. In metro tunnels, power cables and communication cables must be installed on separate trays or separated by divider panels within the same tray to prevent electromagnetic interference and to comply with fire segregation requirements. Cable trays must be protected by cover plates within two meters of the ground and in areas vulnerable to mechanical damage, with covers secured using stainless steel clips at a minimum density of 3 clips per 3 metres under normal conditions and 7 clips per 3 metres where wind speeds exceeding 60 km/h may occur. Fire stopping is critical at tunnel wall penetrations: all tray penetrations through fire-rated walls and floors must be sealed with approved fire-stop materials to maintain the integrity of the compartmentation. Field cutting of fibreglass trays must be followed by sealing of all cut edges with a compatible resin to restore the resin-rich surface and prevent moisture ingress. When these installation practices are followed, a fire retardant fibreglass cable tray delivers reliable, maintenance-free cable support in tunnels and metro systems for decades, providing essential fire safety performance for the protection of passengers, personnel, and critical infrastructure.