Spacing of cable tray tee supports

Cable tray tees should be supported at intervals that prevent undue stress on cables, typically with supports every 6 feet for tees, in line with NEC 392 and manufacturer guidelines.

General Tee Support Guidelines

Cable tray tees, which branch off from the main tray to equipment or devices, require proper support to maintain structural integrity and prevent mechanical stress on the cables. Unsupported spans for tees should generally not exceed 6 feet (1.8 meters); if the span is longer, additional supports are required to prevent sagging and strain on the conductors (Electrical Trader, NEC 392) .

Support Spacing Considerations

• Manufacturer Specifications: Always consult the tray manufacturer's load capacity chart, as spacing may vary depending on tray type, material, and cable weight .
• Straight Runs vs Tees: Standard straight trays typically require supports every 6 to 10 feet, while heavy-duty or long-span trays can extend up to 20 feet between supports. Tees, however, are shorter and carry branching loads, so 6 feet is a common maximum span .
• Vertical and Angled Runs: Cables should be fastened to transverse members to maintain stability and prevent shifting. Hanging rod supports for vertical runs should be at least 8 mm in diameter .

Additional Installation Practices

• Cable Ties: When binding cables within the tee, the distance between ties should not exceed 1.5 meters to maintain order and prevent sagging .
• Clearances: Maintain at least 12 inches of vertical clearance above trays for installation and maintenance access, and ensure proper spacing from ceilings or other obstructions .
• Fill Rate: Do not exceed 50% of the tray's cross-sectional area to allow airflow and prevent overheating .

Environmental and Safety Considerations

• Hazardous Areas: In fire-resistant or explosion-proof zones, spacing may need adjustment to maintain safe distances from surrounding structures .
• Material Selection: Aluminum, steel, or FRP trays should be chosen based on environmental conditions and load requirements to ensure long-term stability . By following these guidelines, cable tray tees will remain structurally sound, maintain proper cable support, and comply with NEC and industry standards, ensuring both safety and operational efficiency.