Cable tray grounding connection strip

A cable tray grounding connection strip is used to bond metallic cable tray sections and provide a safe path for fault currents, ensuring compliance with NEC grounding requirements.

Purpose of a Grounding Connection Strip

A grounding connection strip serves as a mechanical and electrical bonding point for metallic cable trays. It ensures that all sections of the tray are electrically continuous and connected to the equipment grounding conductor (EGC), providing a low-impedance path for fault currents to safely flow to ground, reducing the risk of electric shock, equipment damage, or fire .

Installation and Best Practices

• Bonding Cable Tray Sections: Each tray section should be bonded to adjacent sections using grounding clamps or connection strips. This maintains electrical continuity across the entire tray system .
• Connection to EGC: If a separate EGC conductor is installed in the tray, it should be connected to the grounding strip to ensure proper fault current path .
• Material Considerations: Use tin- or zinc-plated connectors when bonding to aluminum trays to prevent electrolytic corrosion. Bare copper conductors should generally be avoided in aluminum trays .
• Mechanical Stability: Grounding strips also help anchor the EGC, preventing it from being displaced by magnetic forces during fault conditions .
• Compliance with NEC: All metallic cable trays must be grounded according to NEC Article 250.96, regardless of whether the tray itself is used as the EGC. Aluminum trays should not be used as EGCs for circuits with ground-fault protection above 2000 A, and steel trays above 600 A .

Design Considerations

• Cross-Sectional Area: The grounding strip and tray metal must meet minimum cross-sectional area requirements to safely carry fault currents. This is typically specified in manufacturer catalogs or NEC tables, such as Table 392.60(A) for ladder or trough trays .
• Insulation: When using insulated EGC conductors, remove insulation at bonding points to ensure a solid metal-to-metal connection .
• Labeling: If the tray is intended to serve as an EGC, it should be marked or labeled by the manufacturer to indicate its classification and metal area available for grounding .

Safety and Maintenance

• Low Grounding Resistance: Ensure the grounding system has a resistance ideally 4 ohms or less to maintain effective fault current diversion .
• Environmental Protection: Keep grounding strips and connections free from moisture, corrosive environments, and flammable materials to maintain long-term reliability .
• Periodic Inspection: Regularly inspect bonding connections for corrosion, looseness, or damage to maintain electrical continuity and safety . By following these practices, a cable tray grounding connection strip ensures electrical safety, NEC compliance, and reliable operation of the cable tray system in industrial, commercial, or data center environments .