Classification Standards for 90-degree Elbows in Cable Trays

90-degree elbows in cable trays are classified primarily by NEMA tray class compatibility, side rail flange width, and splice plate configuration. Overview90-degree elbows are essential fittings in cable tray systems, allowing cables to change direction smoothly while maintaining mechanical support and proper bend radius. They are available in horizontal and vertical orientations and are designed to match the specifications of the straight cable tray sections they connect to.

Classification by NEMA ClassesCable tray elbows are typically classified into three or four classes based on the NEMA standard of the tray system: Class 1: Compatible with NEMA Classes 12B and 12C. These trays have 1-1/8" wide side rail flanges and 4-hole splice plates. They are suitable for light-duty applications.

Class 2: Compatible with NEMA Classes 20A, 20B, and 20C. These trays feature 2" wide side rail flanges and 4-hole splice plates, supporting medium-duty loads. Class 3: Designed for NEMA Classes exceeding 20C.

These systems have 2-3/8" wide side rail flanges and 8-hole splice plates, suitable for heavy-duty applications. Class 4 (optional, depending on manufacturer): Used with 8" high cable tray systems like A820E, featuring 2-3/4" wide side rail flanges and 8-hole heavy-duty splice plates for very high load capacity.

Additional Considerations

Radius Sizes: Standard elbow radii are typically 12", 24", and 36", allowing for smooth cable bends without exceeding the cable's minimum bend radius. Orientation: Elbows can be horizontal (changing direction along the same plane) or vertical (changing elevation), and the classification applies to both types. Material and Finish: Elbows are manufactured to match the tray material (steel, aluminum, or stainless steel) and may have finishes like hot-dip galvanized, bare, or powder-coated to ensure corrosion resistance.

Summary

The classification of 90-degree elbows in cable trays is primarily determined by NEMA tray class, flange width, and splice plate configuration, with additional factors including bend radius, orientation, and material finish. Selecting the correct class ensures mechanical compatibility, proper load support, and safe cable routing in electrical and data installations.