How to connect double-layer cable trays

Two-layer cable trays are connected using vertical risers, support brackets, and modular fittings to securely stack and align the trays while maintaining structural integrity and proper cable management.

Overview of Two-Layer Tray Connections

Two-layer or multi-tier cable tray systems are used when multiple circuits or cable types need separation while conserving space. The connection involves mechanical support, alignment, and electrical continuity.

Mechanical Connection

1. Vertical Risers or Standoffs: The upper tray is supported above the lower tray using vertical risers or standoffs, which are typically made of steel or aluminum. These risers are bolted to the lower tray or its support structure to maintain a fixed separation distance and prevent sagging .
2. Support Brackets: L-shaped or custom brackets attach to the side rails of the lower tray and provide mounting points for the upper tray. Brackets ensure stability and allow for precise alignment of the trays .
3. Modular Fittings: Standard tray fittings such as tees, elbows, and couplers are used to connect sections of the upper and lower trays. These fittings maintain continuity and allow the trays to navigate around obstacles while keeping the two layers properly aligned .

Cable Management Considerations

• Rung Alignment: For ladder-type trays, the rungs of the upper tray should be positioned to avoid interference with the lower tray's rungs, ensuring proper cable support and ventilation .
• Separation Distance: Adequate spacing between layers prevents overheating and allows for easy cable installation and maintenance. The spacing is typically determined by cable size, heat dissipation requirements, and code compliance .

Electrical and Safety Compliance

• Grounding: If the cable trays are metallic, the upper and lower trays should be electrically bonded to maintain grounding continuity. This can be achieved using bonding jumpers or integrated tray connectors .
• Code Compliance: Installation must follow NEC Article 392 or local standards, ensuring proper support, fill capacity, and grounding for multi-tier systems .

Summary

Connecting two-layer cable trays involves stacking trays using risers or brackets, securing them with bolts or modular fittings, and ensuring proper spacing for cable support and ventilation. Electrical continuity and compliance with safety codes are essential for a reliable and safe installation .