How to install supports for double-row cable trays

Double-row cable tray supports require careful planning, proper spacing, and secure mounting to ensure safe and efficient cable routing.

Planning and Layout

Before installation, determine the types of cables, their total weight, and the anticipated fill for each tray row. Double-row configurations are typically used to separate power and control cables or to increase capacity while maintaining proper ventilation and access for maintenance . A detailed layout plan should be prepared by a qualified designer or engineer, considering building codes, clearances, and structural constraints .

Support Methods

Double-row cable trays can be supported using:

• Trapeze hangers: Ideal for ceiling-mounted trays, providing a rigid horizontal support for both rows .
• Cantilever wall brackets: Suitable for vertical or sidewall installations, allowing trays to extend from the wall while maintaining stability .
• Strut channels and threaded rods: Common for industrial installations, offering flexibility in height adjustment and alignment . Supports should be aligned with the tray rungs and spaced according to the manufacturer's load capacity charts. Typical spans range from 1.5 to 3 meters for steel ladder trays, but exact spacing depends on tray type, cable weight, and environmental conditions .

Installation Steps

1. Mount the supports: Secure trapeze hangers or wall brackets to the building structure using anchors or bolts suitable for the substrate. Ensure supports are level and aligned for both tray rows .
2. Install the lower tray row first: Position the first tray row on the supports, ensuring proper alignment and secure attachment with tray clamps or bolts.
3. Install the upper tray row: Place the second tray row above the first, maintaining a minimum vertical clearance between rows to allow cable access and heat dissipation. Typically, a 150–200 mm clearance is recommended, but check manufacturer specifications .
4. Secure trays together: Use cross-bracing or inter-row connectors if provided by the manufacturer to prevent lateral movement and maintain structural integrity .
5. Check level and alignment: Ensure both rows are parallel and level along the entire run. Adjust supports as necessary before cable installation.

Cable Routing and Fill

• Calculate the maximum fill for each tray row according to NEC 392.22 or local standards to prevent overheating .
• Route cables neatly, grouping by type and function. Use cable ties or straps at regular intervals to maintain organization.
• Avoid overfilling trays, and ensure cables do not sag between rungs or supports.

Material and Environmental Considerations

• Steel or stainless steel trays are common, with galvanization or coatings for corrosion protection .
• In corrosive or high-moisture environments, consider FRP or stainless steel trays for durability and safety .

Safety and Compliance

• Only qualified personnel should perform installation, following local electrical codes and occupational safety regulations .
• Ensure all components are compatible and tested as a system to withstand mechanical loads, including cable weight, wind, and potential short-circuit forces . Properly installed double-row cable tray supports provide efficient, safe, and maintainable cable management, supporting both operational reliability and future expansion.