Grounding of flat iron for vertical shaft cable tray

Metallic cable trays, including vertical shaft installations, must be properly grounded and bonded to ensure electrical safety and code compliance.General Grounding RequirementsAll metallic cable trays, including flat iron trays used in vertical shafts, must be grounded according to NEC Article 250.96 regardless of whether the tray itself serves as an equipment grounding conductor (EGC) . Grounding ensures that any fault current is safely conducted to the building's grounding system, reducing the risk of electric shock or equipment damage.Using the Tray as an Equipment Grounding ConductorA metallic cable tray can serve as the EGC if it is electrically continuous and properly bonded at all splice points . For vertical shaft installations:Bond each tray section using grounding clamps or bonding jumpers to maintain electrical continuity.Ensure mechanical tightness to prevent separation under fault current conditions.If an EGC conductor is installed inside the tray, it should be bonded to each or alternate tray sections to enhance safety and prevent the conductor from being displaced by magnetic forces during a fault .Material ConsiderationsAluminum trays: Avoid bare copper EGCs due to potential electrolytic corrosion in moist environments. Use insulated conductors with insulation removed only at bonding points, and employ tin- or zinc-plated connectors .Steel or iron trays: Standard bonding clamps or jumpers can be used to connect tray sections and the building grounding system.Vertical Shaft SpecificsEnsure continuous grounding along the vertical run to prevent potential differences between sections.Use mechanical clamps or bonding jumpers at each splice or support point to maintain continuity.Maintain proper clearances and support spacing to comply with NEC Article 392 and facilitate safe installation and maintenance .Best PracticesVerify that all tray sections are mechanically and electrically continuous.Use bonding jumpers where mechanical connections alone may not provide reliable continuity.Inspect connections periodically, especially in vertical shafts where vibration or thermal expansion may loosen clamps.Follow manufacturer guidelines for tray-specific grounding methods, as outlined in technical guides such as those from Legrand or BEAMA . By following these practices, a flat iron cable tray in a vertical shaft can be safely grounded, ensuring compliance with NEC standards and minimizing electrical hazards.