Requirements for cable tray screws

Cable tray support screws must be selected and installed according to IEC 61537 standards, considering tray width, load, and environmental conditions.

Screw Selection and Standards

Cable tray support screws are used to secure trays and fittings, ensuring mechanical stability and safe cable routing. They must comply with IEC 61537, which governs cable tray systems and ladder systems, ensuring they can handle expected loads, environmental factors, and maintain electrical continuity when required . Screws should be compatible with the tray material (steel, stainless steel, or aluminum) and any corrosion protection applied, such as galvanization or coatings .

Screw Size and Type

• Common screw type: FRS M6 truss-head bolts with combination nuts are recommended for joint plates and tray connections .
• Drill hole diameter: Holes in the tray rail and base should be ≥ 7 mm to accommodate screws and prevent transverse bending under load .
• Number of screws:
  • For a tray side height of 60 mm, use 4 screws per connector.
  • For a tray width of 300 mm, use 3 screws per joint plate. Wider trays (≥ 400 mm) require a joint plate to prevent bending .

Installation Guidelines

• Joint plates: Place centrally on the joint area and fasten after connectors are mounted. For trays ≤ 300 mm, joint plates are optional; for trays ≥ 400 mm, they are mandatory .
• Edge protection: Attach edge protection strips at cut edges to prevent cable damage if no joint or end plates are used .
• Load considerations: Screws must be selected based on the expected cable load and environmental conditions, including indoor/outdoor use and temperature ranges from ‒20 °C to 120 °C .
• Spacing: Follow manufacturer recommendations and standard guidelines to ensure proper support spans and prevent sagging or mechanical failure .

Safety and Compliance

• Only trained personnel should perform installation to avoid injury from sharp edges or improper fastening .
• Ensure all screws and connectors are compatible with the tray system to maintain structural integrity and compliance with IEC 61537 .
• For high-load or wide trays, additional support elements and joint plates are required to distribute forces evenly . By following these requirements, cable tray support screws will provide secure, code-compliant, and durable support for electrical cables in industrial and commercial installations.