Cable tray connection plate size requirements

Cable tray connecting plates (splice plates) should match the tray width and be installed with at least two bolts per side, positioned near the tray ends, with one plate per support span to ensure structural integrity.

General Guidelines

Splice plates are used to join two sections of cable tray and maintain both mechanical strength and electrical continuity. The key requirements include:

• Plate Width and Length: The connecting plate should match the width of the cable tray to ensure full support along the side rails. The length should be sufficient to allow at least two bolts per side, typically positioned near the ends of the tray sections for maximum stability (Eaton B-Line series guide) .

• Bolt Requirements: Each splice plate should be secured with two bolts per side, which ensures proper clamping and maintains structural integrity. Some designs, like Eaton's KwikRail, feature a splice-retention groove to guide the plate and simplify installation .

• Placement Relative to Supports: It is recommended to place only one splice plate per support span. The splice plate should be positioned close to the support point, ideally at 1/4 of the span from the support, to minimize stress and deflection at the joint .

• Material and Finish: Splice plates are typically made of the same material as the tray (steel, aluminum, or stainless steel) to maintain corrosion resistance and mechanical compatibility. Aluminum trays should not be used as grounding conductors for circuits above 600 A unless specified .

• Compliance: Installation should follow NEMA BI 50015 and 50016 standards and comply with the National Electrical Code (NEC) or Canadian Electrical Code (CEC) for load, grounding, and safety requirements .

Practical Considerations

• Ensure the tray length is equal to or longer than the support span to allow proper placement of the splice plate .
• For long or extra-long spans, the location of splice plates becomes critical to maintain tray strength and prevent sagging .
• Use appropriate fasteners and torque specifications recommended by the manufacturer to maintain both mechanical and electrical continuity . By following these guidelines, cable tray systems will maintain structural integrity, proper alignment, and compliance with electrical safety standards.