How to model a double-layer cable tray

A double-layer cable tray can be modeled by stacking two cable tray runs on a shared support system, ensuring proper spacing, load capacity, and connectivity in CAD or BIM software.

Design Considerations

When modeling a double-layer cable tray, start with design planning:

• Tray Type and Material: Choose the appropriate tray type (ladder, perforated, or solid-bottom) and material (aluminum, steel, or fiberglass) based on load, environment, and corrosion resistance .
• Load and Fill Capacity: Calculate the allowable cable fill for each tray layer. For example, an 18-inch wide tray may have a fill area of 21 square inches, which must be distributed across both layers .
• Spacing Between Layers: Maintain sufficient vertical clearance between the two layers to allow cable installation, heat dissipation, and maintenance access .
• Supports: Use trapeze or other support systems to hold both layers securely. Trapeze supports can carry multiple trays on a single support structure, optimizing space and reducing the number of supports .
• Thermal Expansion: Account for thermal contraction and expansion, especially in long runs or outdoor installations .

Modeling Workflow in CAD/BIM

1. Import or Create Base Tray: Start by importing a standard cable tray CAD file or creating a tray in your software (SOLIDWORKS, AutoCAD, Revit, etc.), .
2. Set Parameters: Define tray dimensions, material properties, and connectivity parameters. In Revit, this includes width, height, and bend radius .
3. Duplicate for Second Layer: Copy the first tray and position it above the first layer, maintaining the required vertical clearance.
4. Add Accessories: Include bends, tees, couplings, junction boxes, and other fittings for both layers to ensure continuity and proper routing .
5. Support Placement: Model trapeze or bracket supports that can hold both layers. Ensure supports are spaced according to load and manufacturer recommendations .
6. Annotation and Documentation: Label each tray layer, add cable fill schedules, and generate drawings for construction or coordination with other disciplines .

Best Practices

• Plan for Future Expansion: Leave extra space in the upper layer for additional cables.
• Coordinate with Other Systems: Ensure the double-layer tray does not interfere with HVAC, piping, or structural elements.
• Optimize Tray Layout: Minimize bends and intersections to reduce installation complexity and voltage drop.
• Use CAD Libraries: Utilize supplier-certified CAD models for accurate dimensions and fittings . By following these steps, you can create a precise, professional double-layer cable tray model that meets both design and installation requirements, while optimizing space and ensuring safety.