Cable tray fixing screw techniques

Screw fixing of cable trays involves using bolts, nuts, and clamps to securely join tray sections and fittings, ensuring load stability, safety, and compliance with standards.

Overview of Screw Fixing

Screw-on cable tray systems are designed to support and route cables safely, meeting IEC 61537:2006 standards for low-voltage installations . They can be mounted indoors or outdoors, depending on corrosion protection, and are suitable for ambient temperatures from ‒20 °C to 120 °C . Only trained electrical personnel should perform installation, and protective gloves are recommended due to sharp edges .

Fastening Methods

1. Truss-Head Bolts and Combination Nuts
   • Used to attach fittings to cable tray rails.
   • Provide a strong, reliable connection that can be undone for maintenance or modifications .
2. Double Clamps (Type DOP A2)
   • Secure fittings to the tray without the need for additional welding or complex tools.
   • Suitable for most tray widths (100–600 mm) and side heights (35–110 mm), .
3. Connector Holes
   • Cable trays are pre-drilled with connector holes to align sections and fittings.
   • Fastening material (bolts, nuts, or clamps) is inserted through these holes to join trays securely .

Installation Steps

• Align tray sections: Ensure ends of two tray sections or fittings are properly aligned.
• Insert fasteners: Use bolts, nuts, or clamps through the connector holes.
• Tighten securely: Apply appropriate torque to ensure stability without over-tightening, which could damage the tray.
• Check alignment and load: Confirm that the tray is level and can support the expected cable load .

Types of Fittings

• Straight joins: Use splice plates or flat metal plates with bolts for linear connections.
• Angles and junctions: L, T, or cross-shaped plates allow routing around corners or splits.
• Special fittings: Some systems use snap, slide, or twist mechanisms for faster installation, typically brand-specific .

Safety and Best Practices

• Always follow manufacturer instructions and local electrical codes.
• Design the tray layout according to expected cable load and volume.
• Avoid using trays for unintended purposes, such as walkways, to prevent injury or damage .
• Ensure all connections are tight to prevent sagging, loose joints, or grounding issues . By following these screw fixing methods, cable trays remain secure, durable, and compliant, facilitating safe cable management and easy maintenance.