Cable Tray Binding

Cable tray binding should ensure mechanical stability, electrical continuity, and proper grounding using splice plates, nuts and bolts, and bonding jumpers according to NEC and manufacturer guidelines.

Mechanical Connection

Splice Plates and Fasteners: Cable tray sections are typically joined end-to-end using splice plates, which are flat metal plates with pre-drilled holes. These plates are secured with nuts and bolts, ensuring a strong mechanical connection that prevents sagging or misalignment under load . Proper torque control is essential to avoid loosening due to vibration . Quick-connect systems may also be used for faster assembly, snapping or sliding sections together with minimal tools . Support Placement: Supports should be positioned so that connectors between horizontal tray sections fall between the support point and the quarter-point of the span, avoiding placement at the center or directly on supports . Expansion connectors must be installed at building expansion joints and in long outdoor runs at intervals of approximately 30 meters (100 ft) to accommodate thermal expansion .

Electrical Bonding and Grounding

Bonding Jumpers: All metallic cable tray systems must be bonded together using bonding jumpers to maintain electrical continuity . Grounding should be provided at least every 15 meters (50 ft) and at both ends of the tray system . For expansion joints, a bonding jumper should be installed to ensure continuity . Equipment Grounding Conductor (EGC): Metallic cable trays can serve as the EGC if they meet the minimum cross-sectional area requirements specified in NEC Table 392.60(A), . If a separate EGC is used, it should be bonded to each or alternate tray sections using grounding clamps. For aluminum trays, use insulated conductors with tin or zinc-plated connectors to prevent electrolytic corrosion . Conduit Drop-Outs: Any conduit entering or leaving the tray should be bonded to the tray using a compression lug or grounding bushing to maintain continuity .

Installation Best Practices

• Inspect all materials and obtain approval from the consulting engineer before installation .
• Ensure all personnel are trained and follow safety procedures .
• Avoid placing bare copper EGCs in aluminum trays; use insulated conductors instead .
• Verify that all tray sections are level, aligned, and securely fastened before cable installation .
• Maintain proper spacing and protection for cables outside the tray using conduit or other approved methods . Following these practices ensures mechanical stability, electrical safety, and long-term reliability of the cable tray system while complying with NEC and manufacturer requirements.