Diameter of internal thread on cable tray elbow

The internal thread diameter on cable tray elbows typically corresponds to standard conduit or accessory thread sizes, commonly M16, M20, or 3/8"–1/2" NPT, depending on the manufacturer and tray system.

Overview

Cable tray elbows are used to change the direction of cable runs while maintaining support and strain relief. The internal threads on these elbows are designed to accept bolts, studs, or conduit fittings that secure covers, clamps, or accessories. The exact diameter is not universal and depends on the tray manufacturer, material, and size of the elbow.

Common Thread Sizes

Metric threads: M16, M20, M24 are frequently used for aluminum or steel cable tray elbows in industrial and commercial installations. Imperial threads: 3/8"–1/2" NPT or UNC threads are common in North American systems, especially for steel ladder trays. Accessory compatibility: Many manufacturers design elbows to match the thread size of standard clamps, grounding lugs, or cable gland fittings, ensuring interchangeability with the tray system.

Installation Considerations

Always verify the manufacturer's datasheet for the specific elbow model to ensure the correct thread size. Using the wrong thread diameter can compromise mechanical stability and strain relief. For aluminum trays, threads are often tapped directly into the elbow body, while steel elbows may use inserted nuts to achieve the required thread size.

Recommendation

If the exact internal thread diameter is required for a specific cable tray elbow, consult the technical datasheet of the manufacturer (e.g., Unitray, Legrand, ABB, Hubbell) or contact their technical support. This ensures compatibility with clamps, covers, and other accessories while maintaining compliance with CSA, UL, or NEC standards.