Copper wire used at cable tray connections

Copper wire is commonly used as an equipment grounding conductor (EGC) at cable tray connections, but proper bonding, insulation, and corrosion prevention are essential for safety and code compliance.

Grounding Practices

Copper wire can serve as the EGC in or on a cable tray system, providing a safe path for fault currents to the ground. When installed, the copper wire should be bonded to each or alternate cable tray sections using grounding clamps. This ensures electrical continuity and mechanically secures the wire so that magnetic forces during fault conditions do not dislodge it from the tray .

Material Compatibility

A bare copper conductor should not be placed in an aluminum cable tray due to the risk of electrolytic corrosion in moist environments. In such cases, it is recommended to use an insulated copper conductor and remove the insulation only at bonding points, using tin- or zinc-plated connectors to attach to the tray, raceways, or equipment enclosures .

Connection Methods

Copper grounding wires can be connected using:

• Grounding clamps or brackets at tray joints to maintain electrical continuity.
• Bolts or welds to secure the wire at each connection point, preventing breaks and ensuring low-resistance paths .
• Full-length continuous conductors along the tray for consistent grounding, especially in long runs .

Code Considerations

• All metallic cable trays must be grounded according to NEC Article 250.96, regardless of whether the tray itself is used as the EGC .
• The minimum cross-sectional area of the tray or wire must meet NEC Table 392.60(A) requirements for the circuit's protective device rating .
• Aluminum trays should not be used as EGCs for circuits with ground-fault protection above 2000 amperes, and steel trays are limited to 600 amperes .

Best Practices

• Use insulated copper wire in aluminum trays to prevent corrosion.
• Bond the wire at every tray section or at alternate sections for mechanical and electrical reliability.
• Ensure low grounding resistance, ideally 4 ohms or less, to maintain effective fault protection .
• Avoid placing the wire near flammable or corrosive materials to maintain safety and longevity . By following these practices, copper wire at cable tray connections will provide a reliable, code-compliant grounding path that protects both equipment and personnel from electrical faults.