Elbows for horizontal and vertical cable trays

Horizontal and vertical elbows in cable tray systems are connected using properly supported fittings that maintain cable bend radius, structural integrity, and electrical continuity.

Purpose of Elbows

Elbows in cable tray systems allow the routing of cables around corners or changes in elevation. Horizontal elbows change the direction of the tray along the same plane, while vertical elbows transition the tray between different elevations or floors. Proper connection ensures smooth cable transitions, prevents damage, and maintains the tray's load-bearing capacity.

Connection and Support

Positioning: Elbows should be installed so that the connectors between straight tray sections and elbows fall between support points or near the quarter-point of the span, avoiding placement directly on supports or at the center of spans. This prevents undue stress on the tray and maintains alignment. Support Hangers: Both horizontal and vertical elbows require adequate support.

Vertical hangers or rods should be positioned to allow proper alignment and minimal horizontal adjustment. The shorter the vertical rod, the less horizontal adjustment is possible, so careful planning is essential. Clamps and Fasteners: Ladder tray systems often use clamps (e.g., SC or DC clamps) to secure elbows to the tray rails.

Washers and hex nuts are used to ensure the tray is lifted to the correct elevation and remains stable. Cable Bend Radius: Elbows must maintain the minimum bend radius for the cables to prevent damage. Smooth, gradual bends are preferred, especially for sensitive instrumentation or control cables.

Electrical Continuity

Bonding Jumpers: Each elbow connection should include a bonding jumper to maintain electrical continuity across the tray system. This is particularly important at expansion joints or where elbows connect to different tray sections. Grounding: Cable trays, including elbows, should be grounded at intervals (e.g., every 15 m or 50 ft) and at both ends to ensure safety and compliance with electrical codes.

Installation Tips

Precut rods and supports can save time, but care must be taken to avoid damaging threads. Use a string or wire to establish elevations for vertical transitions. Ensure connectors and elbows are aligned before tightening fasteners to prevent misalignment and stress on the tray system.

Standards Compliance

Installation should follow NEC, NEMA VE 2, and manufacturer guidelines to ensure mechanical support, proper cable management, and safety. Properly installed elbows contribute to a reliable, durable, and code-compliant cable tray system. By following these practices, horizontal and vertical elbows can be effectively integrated into cable tray systems, ensuring smooth cable routing, structural stability, and electrical safety.