Method for Positioning Cable Tray Tees

Cable tray tees should be positioned with proper alignment, supported at appropriate intervals, and installed according to manufacturer and standard guidelines to ensure structural integrity and electrical safety.

Tee Positioning and Alignment

When installing a cable tray tee, the branch should be aligned with the main tray run to maintain a smooth cable path and avoid sharp bends. The tee should be positioned so that the connector between the main tray and the branch falls between the support point and the quarter-point of the span, avoiding placement at the center of unsupported spans or directly on supports, which can cause stress on the tray and connectors .

Support Requirements

• Support spacing: Both the main tray and the tee branch must be supported according to the manufacturer's specifications and standards such as BS EN 61537 or NEMA VE 2. Supports should be installed at intervals that prevent sagging and maintain the tray's structural integrity .
• Hanger installation: Use threaded rods, brackets, or other approved hangers. Elevations should be determined using a laser level or transit to ensure the tee aligns with the main tray run .
• Pre-cut supports: For efficiency, threaded rods and horizontal supports can be precut to the required lengths, ensuring that threads are not damaged during installation .

Connection and Expansion

• Connector installation: Use compatible connectors designed for the tray system. Ensure that the tee allows for longitudinal movement to accommodate thermal expansion and contraction .
• Expansion joints: Provide expansion connectors at building expansion points and in long outdoor runs, typically every 30 meters (100 ft), to prevent stress on the tray system .
• Bonding and grounding: Install bonding jumpers at each expansion joint and ground the tray at intervals of 15 meters (50 ft) and at both ends to maintain electrical continuity .

Practical Tips

• Visual alignment: Ensure the tee branch is level and properly oriented to avoid cable strain.
• Avoid overloading: Do not use the tray as a walkway or support for personnel, as this can damage the system .
• Material considerations: Select tray materials (steel, stainless steel, aluminum) suitable for the environment to prevent corrosion and maintain mechanical strength . By following these guidelines, cable tray tees can be positioned safely and efficiently, ensuring reliable cable support and compliance with electrical installation standards.