How to connect the cable tray ground wire

Connect the cable tray ground wire by securely bonding a properly sized equipment grounding conductor (EGC) to the tray using clamps or bolts, ensuring continuity and low impedance to safely carry fault currents.

Steps to Connect the Ground Wire

1. Choose the Right Grounding Method

• Full-Length Grounding Conductor: Run a continuous EGC along the entire cable tray length for a reliable path for fault currents .
• Cable Tray as Ground: For metal trays that meet conductivity and strength requirements, the tray itself can serve as the EGC .
• Bonding at Joints: Connect the grounding wire at each tray section using clamps, bolts, or welds to maintain electrical continuity . 2. Select Appropriate Materials
• Copper Wire: Excellent conductivity, corrosion-resistant, ideal for most installations .
• Hot-Dip Galvanized Steel: Durable and corrosion-resistant, suitable for industrial environments .
• Stainless Steel: Best for harsh or corrosive environments .
• Avoid bare copper in aluminum trays to prevent electrolytic corrosion; use insulated conductors with exposed bonding points and tin or zinc-plated connectors . 3. Bonding and Securing the Wire
• Use UL-listed grounding clamps or bolts to attach the EGC to the tray every 50–100 feet, or at each tray section for maximum safety .
• Secure the wire to the tray every 10–20 feet to prevent movement under fault conditions .
• Ensure all connections are mechanically strong and electrically continuous to maintain a low-impedance path . 4. Verify Grounding Effectiveness
• Check for continuity along the entire grounding path.
• Measure grounding resistance, ideally 4 ohms or less, to ensure effective fault current dissipation .
• Confirm compliance with NEC requirements for conductor sizing and tray bonding (NEC Sections 250-51, 250-95, 318-6(a)), . 5. Additional Considerations
• Keep grounding wires away from flammable or corrosive materials .
• Ensure compatibility of materials to prevent corrosion and maintain long-term performance .
• For multiconductor cables with individual EGCs, parallel the EGCs with the tray and bond as needed to maintain a low-impedance path . By following these steps, the cable tray grounding system will provide a safe, continuous, and low-resistance path for fault currents, protecting personnel and equipment from electrical hazards.