Cable tray ground wire connection copper plate

A copper plate can be used to bond a cable tray to the ground by providing a secure, low-resistance connection between the tray and the equipment grounding conductor (EGC).

Purpose of Grounding Cable Trays

Grounding a cable tray ensures that any stray electrical currents are safely directed to the earth, preventing electric shocks, equipment damage, or fire hazards. The cable tray itself can serve as an EGC if it meets NEC requirements, but a separate grounding conductor is often used for added safety and reliability .

Using a Copper Plate for Grounding

A copper plate acts as a bonding interface between the cable tray and the grounding system. The plate provides a large contact area, ensuring a low-resistance path for fault currents. Key points include:

• Material Compatibility: Use copper or tin/zinc-plated connectors when bonding to aluminum trays to prevent electrolytic corrosion .
• Connection Method: The copper plate is typically bolted or clamped to the tray at splice points or sections where grounding is required. The grounding wire is then attached to the plate using a secure mechanical connection, such as a bolt or grounding clamp .
• Insulation Considerations: If using an insulated copper conductor, remove insulation at the bonding point to ensure direct metal-to-metal contact .
• Mechanical Stability: The copper plate helps anchor the grounding wire, preventing it from being displaced by magnetic forces during fault conditions .

Installation Guidelines

• Ensure the cable tray system is electrically continuous; gaps between sections should not exceed 6 feet (1.8 meters) without bonding jumpers .
• Verify that the tray's metal cross-sectional area meets NEC 392.60(A) requirements if the tray is used as an EGC .
• For aluminum trays, avoid bare copper wires in moist environments; use insulated conductors with proper bonding connections .
• Clean the tray surface at the bonding point to remove paint, rust, or oxidation to maintain a reliable electrical connection .

Best Practices

• Use UL-classified trays and connectors to ensure compliance with safety standards .
• Consider running a full-length grounding conductor along the tray for continuous protection .
• Inspect connections periodically for corrosion or loosening, especially in harsh environments . By following these practices, a copper plate can provide a reliable and safe connection between a cable tray and the grounding system, ensuring effective fault current management and compliance with electrical codes.