Cable tray ground tee installation

A ground tee in a cable tray system should be installed using proper bonding clamps to ensure electrical continuity and mechanical stability, following NEC grounding requirements.

Purpose of a Ground Tee

A ground tee is used to provide a reliable grounding point at a branch or intersection in a cable tray system. It ensures that all sections of the tray maintain electrical continuity and that the equipment grounding conductor (EGC) is properly bonded to the tray, enhancing safety and reducing electrical noise in control or signal cables .

Installation Steps

1. Position the Tee: Align the tee section with the main cable tray run, ensuring proper support and spacing according to the tray manufacturer's guidelines .
2. Secure the Tray Sections: Use the manufacturer-recommended hardware to connect the tee to the main tray. Ensure that the metal-to-metal contact is clean and free of paint or corrosion to maintain conductivity .
3. Bonding the EGC: If an EGC conductor is present, attach it to the tee using grounding clamps. This provides both electrical continuity and mechanical anchoring, preventing the conductor from being displaced under fault current conditions .
4. Material Considerations: Avoid using bare copper conductors in aluminum trays to prevent electrolytic corrosion. Use insulated conductors and remove insulation only at bonding points with tin- or zinc-plated connectors .
5. Verify Continuity: After installation, test the continuity of the grounding path to ensure the tee and all tray sections are electrically bonded and meet NEC Article 250 requirements .

Best Practices

• Bond each or alternate tray section to the EGC for enhanced safety, even if not strictly required by the NEC .
• Ensure the metal area of the tray meets the minimum cross-sectional requirements if the tray itself is used as the EGC, as specified in NEC Table 392.60(A), .
• For wire mesh trays, a separate grounding conductor is generally not required, but a low-impedance path to a non-system ground is recommended to reduce noise .

Safety and Compliance

• All metallic trays must be grounded regardless of whether they serve as the EGC .
• Steel trays should not be used as EGCs for circuits with ground-fault protection above 600 A, and aluminum trays above 2000 A .
• Follow manufacturer-specific installation guides, such as Cablofil manuals, for proper cutting, bending, and tee installation techniques . By following these steps and best practices, a cable tray ground tee can be installed safely, ensuring both mechanical stability and electrical grounding compliance.