Requirements for Cable Tray Installation in Tunnels

Cable tray supports in tunnels must meet mechanical, fire, corrosion, and installation standards, ensuring safe and reliable cable management under tunnel-specific conditions.

Material and Corrosion Resistance

Cable tray supports in tunnels are typically made from stainless steel, galvanized steel, aluminum, or GRP (glass-reinforced plastic) depending on environmental conditions and corrosion risk. Stainless steel (EN 10088-2) is preferred for high humidity or chemical exposure, while GRP offers halogen-free, self-extinguishing properties suitable for fire-sensitive areas. Proper surface treatment or coatings are essential to prevent corrosion over the system's lifespan.

Mechanical Strength and Load Requirements

Supports must withstand the weight of cables, environmental loads, and short-circuit forces. Standards such as IEC 61537 and BS EN 61537 define load testing methods to validate tray strength. Span lengths and support spacing should be designed to prevent sagging or deformation, typically with rung spacing of 150–230 mm for ladder-type trays and 2-meter spans for wire mesh trays.

Supports must not be used as walkways or for personnel support to avoid injury and system damage.

Fire Safety and Resistance

Tunnel installations require fire-resistant cable trays and supports to maintain critical systems during a fire. Standards like DIN 4102-12 and national equivalents specify that the complete system (trays, supports, and cables) must maintain functionality for 30, 60, or 90 minutes under fire conditions. Firestop modules, such as EZ-Path, can be installed to prevent fire spread through walls or penetrations.

Installation Guidelines

Supports must be securely anchored to tunnel walls, ceilings, or beams, accommodating tunnel geometry such as curves, slopes, or downward runs. Cable trays should be installed without damaging conductors, maintaining minimum bend radii and proper fill ratios to prevent overheating. Use compatible accessories (bends, risers, brackets) designed for the specific tray system to ensure mechanical integrity and compliance with standards.

Installation should be performed by competent personnel familiar with electrical installation practices and safety requirements.

Compliance and Certification

Cable tray supports must comply with IEC 61537, BS 6946, and relevant national standards.

C

E marking or third-party certification (UL, IMQ, LCIE) ensures compliance with mechanical, electrical, and fire safety requirements. Regular inspection and maintenance are recommended to ensure long-term performance in tunnel environments.

Summary

Installing cable tray supports in tunnels requires careful consideration of material selection, mechanical strength, fire resistance, proper anchoring, and compliance with international and national standards. Following these requirements ensures safe, durable, and reliable cable management for critical electrical and communication systems in tunnel environments.