The cable tray support quota is calculated based on the total length of the tray divided by the support spacing, plus one, with adjustments for fittings and special sections.

Calculating Support Quantity

To determine the number of supports required for cable tray removal or replacement, the following formula is commonly used: Support Quantity = (Total Length ÷ Support Spacing) + 1 For example, a 20-meter cable tray with supports spaced every 2 meters would require: 20 ÷ 2 + 1 = 11 supports .

Key Considerations

1. Tray Type and Material: Ladder, perforated, or mesh trays have different load capacities, which influence support spacing .
2. Load and Installation Standards: Support spacing typically ranges from 1.5 to 3 meters depending on the tray type, cable weight, and environmental conditions .
3. Fittings and Special Sections: Elbows, tees, and crosses require additional supports. Each fitting may need extra splice plates or hardware, which should be included in the quota .
4. Removal and Reinstallation: When removing existing trays, supports may need to be temporarily removed or replaced. The support quota should account for both the removal and the reinstallation process, including any new supports required for upgraded or refurbished trays .

Practical Steps

• Measure the total length of each straight section and each fitting separately.
• Determine the appropriate support spacing based on tray type, load, and standards.
• Apply the formula to calculate the number of supports for each section.
• Add extra supports for elbows, tees, and cross sections as specified by the manufacturer or project guidelines. By following these steps, you can accurately estimate the support quota for cable tray removal and reinstallation, ensuring structural stability and compliance with installation standards .