No joints are allowed in cable trays

Cable trays can have joints, but they must be mechanically secure and electrically continuous to comply with NEC standards.

Mechanical and Electrical Continuity

Cable trays are often installed in sections that are joined together. While joints are allowed, each joint must be mechanically tight and electrically continuous to ensure proper grounding and system safety . Metallic trays, in particular, can serve as equipment grounding conductors (EGC) if they meet NEC requirements, and bonding jumpers may be used at joints to maintain electrical continuity . This ensures that any fault current is safely conducted and reduces the risk of shock or fire.

NEC Guidelines

The National Electrical Code (NEC) does not prohibit joints in cable trays. Instead, it emphasizes that metallic trays must be electrically continuous and properly bonded at all splice points . Section 318-6(a) of the NEC states that while mechanical continuity is not strictly required, electrical continuity is mandatory, and bonding must comply with NEC Section 250-75 . This allows for safe installation even when multiple tray sections are connected.

Best Practices

• Use proper connectors and fasteners to secure tray sections together.
• Bond each joint to maintain a continuous grounding path.
• Verify electrical continuity using appropriate testing methods.
• Consider expansion splice plates in outdoor installations to accommodate thermal expansion .

Summary

The statement "No joints are allowed in cable trays" is incorrect. Joints are permitted, but they must be mechanically secure and electrically continuous to comply with NEC standards and ensure safety. Proper bonding and grounding at each joint are essential to prevent hazards and maintain system reliability .