Cable tray connection bolt holes typically require a diameter of 6–7 mm for M6 bolts, with variations depending on tray width and joint plate usage.

Bolt Hole Diameter and Type

For standard cable tray connections, the recommended drill hole diameter is ≥7 mm to accommodate M6 truss-head bolts and combination nuts . Smaller trays (up to 300 mm width) may allow optional joint plates, while wider trays (400 mm or more) require joint plates to prevent transverse bending . The bolt type commonly used is FRS M6 truss-head bolts, paired with combination nuts for secure fastening .

Tray Width and Screw Requirements

• Tray width 100–300 mm: Typically 3 screws per joint plate; joint plate optional for widths ≤300 mm .
• Tray width ≥400 mm: Joint plate mandatory; number of screws increases to ensure structural stability .
• Side height 60 mm: Recommended 4 screws per connector .

Additional Considerations

• Drill holes should be centrally aligned on the tray rail and base to ensure even load distribution .
• Edge protection strips are recommended if joint plates or bottom end plates are not used, to prevent cable damage .
• Clearance holes in perforated trays may follow 20 mm × 7.5 mm dimensions for cable fixing, depending on manufacturer specifications .

Summary

In practice, M6 bolts with ≥7 mm diameter holes are standard for most cable tray connections, with the number of bolts and joint plate usage determined by tray width and height. Always verify with the manufacturer's technical guide for specific tray models and environmental conditions .