Copper conductors are commonly used to ground cable trays, providing a safe path for fault currents and ensuring compliance with electrical safety standards.

Purpose of Grounding Cable Trays

Grounding cable trays is essential to prevent electric shock, reduce electrical noise, and safely channel fault currents to the earth. Proper grounding ensures that any stray electricity from damaged or leaking conductors is safely directed away from personnel and sensitive equipment, and it facilitates the operation of over-current protective devices like circuit breakers .

Using Copper as the Grounding Conductor

Copper is preferred for grounding due to its excellent electrical conductivity, corrosion resistance, and mechanical strength. A bare copper equipment grounding conductor (EGC) should not be placed in aluminum trays because of the risk of electrolytic corrosion in moist environments; instead, an insulated copper conductor is recommended, with insulation removed at bonding points using tin- or zinc-plated connectors . Copper grounding wires can be run parallel to the cable tray or connected at each tray section to ensure continuity .

Cable Tray as Grounding Conductor

In some installations, the metallic cable tray itself can serve as the EGC, provided it meets NEC requirements and is electrically continuous. Steel trays are less conductive than copper, so they may need to be thicker or supplemented with copper bonding. Aluminum trays conduct well but require careful bonding at joints and removal of paint or coatings to maintain electrical continuity . All metallic trays must be grounded according to NEC Article 250.96, regardless of whether they are used as the EGC .

Installation Best Practices

• Bonding: Use grounding clamps to bond copper conductors to each or alternate tray sections. This ensures mechanical stability and electrical continuity under fault conditions .
• Continuity: Ensure the grounding path is permanent, electrically continuous, and capable of safely carrying fault currents .
• Corrosion Prevention: Use insulated copper conductors in aluminum trays and remove insulation only at bonding points to prevent galvanic corrosion .
• Resistance: Maintain low grounding resistance, ideally 4 ohms or less, to ensure effective fault current dissipation .
• Compliance: Follow NEC sections 250-51, 250-95, 318-3, and 318-6 for grounding and bonding requirements .

Material Selection

• Copper Wire: Excellent conductivity and corrosion resistance; preferred for most installations.
• Hot-Dip Galvanized Steel: Durable and corrosion-resistant, but less conductive than copper.
• Stainless Steel: Suitable for harsh environments with high corrosion potential . By following these practices, copper grounding of cable trays ensures electrical safety, regulatory compliance, and reliable operation of the electrical system.