How to match bolts to cable trays

Select bolts based on tray type, fitting, load, and mounting method to ensure secure and stable cable tray connections.

Understanding Cable Tray Bolt Requirements

Cable trays are connected and secured using bolts, nuts, and clamps. The type of bolt depends on the tray system, tray width, height, and the type of fitting being used. Common bolt types include truss-head bolts (FRS) and combination nuts, which are used to fasten tray rails and fittings securely.

For certain fittings, such as vertical bends or adjustable bend elements, only screw-on methods are allowed.

Steps to Match Bolts to Cable Trays

Identify the Tray Type and MaterialPerforated trays (e.g., MKS, SKS, DKS, EKS, IKS) and unperforated trays (MKSU, SKSU, EKSU) may require different bolt sizes or types. Material (steel, aluminum) affects corrosion resistance and bolt selection; stainless steel bolts are often preferred for aluminum or outdoor trays.

Determine the Fitting or Connection

Straight runs typically use splice plates with bolts and nuts. L, T, or cross-shaped junctions may require multiple bolts to secure the fitting and maintain load stability. Covers may have pre-mounted turn buckles or require additional bolts depending on the design.

Select Bolt Size and Type

Use truss-head bolts (FRS) with combination nuts for most tray-to-tray and tray-to-fitting connections. For double clamps, type DOP A2 may be used to secure fittings to the tray rail. Ensure the bolt diameter matches the tray hole size and the load requirements.

Check Load and Span Requirements

Heavier cable loads or longer spans may require closer bolt spacing or larger bolts to prevent sagging. Standard spacing for mounting brackets is typically 4–5 feet, but closer spacing is recommended for heavy-duty installations.

Ensure Proper Torque and Tightening

Bolts must be tightened to the manufacturer's recommended torque to prevent loosening due to vibration. Use appropriate tools such as wrenches or torque wrenches for consistent fastening.

Additional Tips

Always use bolts and nuts compatible with the tray manufacturer to ensure proper fit and warranty compliance. Inspect connections periodically for loosened bolts or worn components to maintain long-term stability. For quick installations, some systems offer snap, slide, or twist connectors, but these are usually brand-specific.

By following these steps, you can ensure that the bolts you select are matched correctly to your cable tray system, providing a secure, durable, and safe installation.