Length of ladder-type cable tray

Standard ladder cable tray lengths typically range from 12 to 30 feet, with some manufacturers offering lengths up to 40 feet, selected based on support span and load requirements.

Standard Lengths and Selection Criteria

Ladder cable trays are available in standard NEMA lengths of 12, 20, 24, and 30 feet, while some manufacturers, such as Eaton, offer lengths up to 40 feet for special applications. The choice of tray length depends primarily on the support span, which is the distance between supports, and the load the tray must carry, including cable weight and environmental factors like wind, snow, or ice. Short Span Trays: Typically supported every 6 to 8 feet; commonly use 10 or 12-foot tray sections.

Intermediate Span Trays: Supported every 10 to 12 feet; 10 or 12-foot sections are also common. Long Span Trays: Supported every 14 to 20 feet; 20-foot sections are popular.

Extra-

Long Span Trays: Supported at intervals exceeding 20 feet; lengths up to 40 feet may be used, especially for outdoor installations or to reduce the number of supports.

Additional Considerations

Rung Spacing: Wider rung spacing reduces overall strength; small-diameter control cables may use 6, 9, or 12-inch spacing, while large power cables often require 9-inch or wider spacing. Width and Side Rail Height: Wider trays and taller side rails increase load capacity and reduce cable stacking, which is important for heat dissipation and future expansion. Splice Plates: When connecting multiple tray sections, splice plates must be positioned according to the support span to maintain structural integrity.

Material and Duty Class: Steel thickness and tray class affect maximum allowable span and load; heavier-duty trays can span longer distances without additional supports.

Practical Tip

Always select a tray length equal to or longer than the support span to ensure proper mechanical support and prevent sagging. For long outdoor runs, extra-long sections can reduce the number of expensive supports while maintaining structural integrity. By considering support span, load, rung spacing, and material strength, you can select the optimal ladder cable tray length for both indoor and outdoor installations.