Length of cable tray connecting plate

Cable tray connection (splice) plates typically span the width of the tray and are designed to fit within the support span, with lengths varying based on tray width and type.

Standard Guidelines

Cable tray splice plates are used to connect two sections of cable tray while maintaining structural integrity and electrical grounding. The length of the splice plate is generally determined by the width of the cable tray and the support span between supports. It is recommended that only one splice plate be used per support span to minimize stress and deflection at the connection point (Eaton B-Line series guide).

For example, Eaton's KwikRail cable tray uses a splice-retention groove that allows the splice plate to snap into position and be secured with two bolts, ensuring proper alignment and grounding. Flexible horizontal adjustable splice plates are also available for angled or non-standard installations, and these require supports within 24 inches (600 mm) on both sides of the splice plate.

Practical Considerations

Tray Width: The splice plate must match the tray width (e.g., 12", 18", 24", 36") to ensure full coverage and stability. Support Span: The tray length should be equal to or longer than the support span, and the splice plate should be positioned at the midpoint or as recommended by NEMA standards to reduce deflection. Adjustable Plates: For installations requiring horizontal adjustments, splice plates can be cut or adjusted in the field to fit the desired angle, but proper support spacing must be maintained.

Thermal Expansion: In areas with significant temperature variation, expansion splice plates may be used, with supports located within 2 feet of each side to allow for thermal contraction and expansion.

Summary

While there is no single fixed length for all cable tray splice plates, the plate should span the tray width and fit within the support span, typically secured with two bolts. Adjustable and expansion splice plates provide flexibility for angled installations or thermal movement, but proper support spacing is critical to maintain structural integrity and compliance with NEMA standards.