Cable tray and metal connection

Metal cable trays must be properly connected, grounded, and bonded to ensure mechanical stability and electrical safety.Material and Connection ConsiderationsMetal cable trays are typically made from steel (galvanized or stainless), aluminum, or pultruded composites depending on environmental conditions and corrosion resistance requirements . Connections between tray sections can be made using splice plates, screws, or innovative plug systems like OBO's Magic plug, which allow faster installation without additional hardware . Splice plates should ideally be installed at ¼ of the gap between supports rather than at midpoints or directly above supports to maintain structural integrity .Grounding and BondingMetal cable trays can serve as an Equipment Grounding Conductor (EGC) if installed by qualified personnel . All metallic trays must be grounded according to electrical codes (e.g., NEC Article 250.96), regardless of whether they are used as the EGC. When using a separate EGC, it should be bonded to each or alternate tray sections using grounding clamps, which also mechanically secure the conductor to prevent displacement under fault currents . For aluminum trays, bare copper conductors should be avoided to prevent electrolytic corrosion; insulated conductors with stripped ends at bonding points are recommended .Installation Best PracticesMaintain a minimum clearance of 300mm above or between trays for cable installation and maintenance .Ensure electrical continuity across tray sections using proper connectors and bonding methods .Observe the minimum bending radius of cables when installing trays with bends, and place supports no more than 600mm from bends .Store trays in a ventilated, elevated area to prevent corrosion or staining before installation .SummaryProper metal connection in cable trays involves selecting the right material, using appropriate splice plates or plug systems, and ensuring robust grounding and bonding. Following these practices ensures mechanical stability, electrical safety, and compliance with standards while preventing corrosion and potential hazards.