Spacing of cable tray riser supports

For vertical cable tray risers, supports should generally be spaced at intervals of 1.5 to 2 meters to ensure stability and prevent sagging.

Vertical Riser Support Guidelines

Vertical cable tray runs, also known as risers, require proper support to maintain structural integrity and prevent undue stress on cables. Supports should be fixed to the building structure at intervals preferably less than 2 meters, ensuring the tray remains stable and the cables inside are not exposed to mechanical stress or sagging . Hanging rod supports should have a minimum diameter of 8 millimeters to provide adequate strength . At corners or bends, one support should be installed on each side symmetrically to maintain stability .

Horizontal vs Vertical Support Spacing

• Horizontal runs: Supports are typically spaced 1.5 to 3 meters apart, depending on tray type, load, and material. For ladder-type trays, the NEC recommends a maximum of 5 feet (approximately 1.5 meters) between supports, with rungs no more than 9 inches apart .
• Vertical runs: Supports should be closer together than horizontal runs, generally 1.5 to 2 meters, to prevent sagging and maintain cable alignment .

Key Considerations

1. Tray Type and Load: Ladder, perforated, and wire mesh trays have different load capacities. Heavier cable loads may require closer support spacing .
2. Material and Environment: Stainless steel or aluminum trays may allow slightly longer spans, but environmental factors like wind, vibration, or seismic activity may necessitate shorter intervals .
3. Fixed Supports: Install supports at the beginning and end of the riser, at corners, T-junctions, and when the tray exceeds 30 meters in length .
4. Compliance: Ensure spacing aligns with NEC, BS EN 61537, and BS 7671 standards for safety and fire resistance . Fire-resistant supports are recommended to prevent premature failure in case of fire .

Practical Tips

• Secure cables at the top of the riser and every 1.5 meters along the vertical run .
• Avoid cable crossings or overlaps within the tray to maintain organization and airflow.
• Use proper banding and balanced bundling to distribute weight evenly .
• Consider thermal expansion and environmental loads when determining final support spacing .

By following these guidelines, vertical cable tray risers will remain structurally sound, safe, and compliant with electrical installation standards.