Cable Tray Funnel Size Specification Table

Cable tray funnels are designed to transition cable runs between different tray widths or directions, with dimensions based on standard tray widths, side rail heights, and bend radii to ensure proper cable fill and compliance with NEC/NEMA/IEC standards.

Standard Dimensions

Cable tray funnels are typically sized according to the nominal inside width of the trays they connect. Standard widths range from 100 mm (4 in) to 600 mm (24 in) for small to medium applications, and up to 1200 mm (48 in) for large power or solar DC trunk runs. The side rail height (depth) usually ranges from 50 mm (2 in) to 150 mm (6 in), depending on cable stacking requirements and heat dissipation needs.

Material thickness varies by tray type: 1. 2–2. 0 mm for steel, 1.

5–2. 5 mm for aluminum, and wire mesh diameters of 4–6 mm for mesh trays.

Funnel Geometry and Parameters

Transition Angle: Funnels often use a tapered design to gradually reduce or expand tray width. A typical taper angle is 15°–30°, which minimizes cable stress and allows smooth cable pulling. Bend Radius: The minimum bend radius for cables exiting the funnel should be at least 8–12 times the cable diameter to prevent damage and maintain NEC compliance.

Length: The funnel length is determined by the width difference between the trays and the taper angle. For example, a transition from 600 mm to 300 mm with a 20° taper requires a funnel length of approximately 450–500 mm. Material and Finish: Funnels are made from the same material as the connected trays (galvanized steel, stainless steel, or aluminum) to maintain structural integrity and corrosion resistance.

Perforated or solid-bottom designs are chosen based on heat dissipation and cable protection requirements. Cable Fill Considerations: Funnels must maintain the maximum allowable cable fill as per NEC/NEMA guidelines. Overcrowding can lead to overheating and inspection failures.

Typically, the funnel cross-sectional area should match or slightly exceed the smaller tray's capacity.

Installation Notes

Ensure alignment with the main tray to avoid sharp bends or cable kinks. Maintain support spacing consistent with the main tray (usually every 1. 5–2 m for straight runs, closer for transitions).

Use covers or guards if the funnel is in areas with potential mechanical damage or electromagnetic interference. By following these parameters, cable tray funnels can provide a smooth, code-compliant transition between different tray sizes while protecting cables and maintaining structural integrity.