Installation steps for long-span cable trays

Long-span cable trays are installed using properly spaced supports, trapeze or swing hangers, and level cross members to ensure structural stability and safe cable management.

Planning and Design

Before installation, a system designer or engineer should plan the layout, considering building codes, equipment specifications, clearances, and load requirements . The design must account for:

• Tray type and material (steel, stainless steel, aluminum, or galvanized) based on environmental conditions .
• Cable load and width to determine tray size and spacing .
• Support spacing for long spans, typically using trapeze or swing hangers .
• Thermal expansion and contraction allowances for long runs .

Support Structures

Trapeze or swing supports are commonly used for long-span installations. The procedure includes:

1. Install vertical hangers at calculated intervals along the span. Thread hex nuts 25–50 mm above the tray bottom.
2. Attach cross members with square washers and ensure vertical hangers pass through the cross member holes, which should be slightly larger than the all-thread diameter for adjustment .
3. Level the cross member using the bottom set of hex nuts, then adjust the top nuts to snugly secure the tray.
4. Attach tray clips to the cross member, allowing minimal horizontal adjustment once hangers are in place .

Tray Installation

• Bundle and transport straight lengths on flat deck trailers to prevent damage .
• Use splice plates at joints to maintain structural integrity and alignment .
• Ensure proper rung spacing (typically 150–230 mm) to support cables and maintain minimum bend radius .
• Cables may enter or exit from the top or bottom of the tray, and tie-downs should be used in vertical or horizontal runs to maintain cable positions .

Safety and Compliance

• Installation must comply with local electrical codes (e.g., CEC, NEC, BS EN 61537) and safety standards .
• Cable trays are supports, not walkways, and should not carry personnel .
• Ensure adequate grounding and bonding to prevent electrical hazards .

Best Practices

• Minimize field alterations; follow the engineer's layout for optimal performance .
• Consider environmental factors such as corrosion, temperature extremes, and electromagnetic interference when selecting materials .
• Maintain clearances from other services and allow for future cable additions .

By following these steps, long-span cable trays can be installed safely, efficiently, and in compliance with industry standards, ensuring reliable cable management for industrial and commercial applications.