Kgb connection to cable tray

A KGB connection refers to using a grounding/bonding clamp to connect the Equipment Grounding Conductor (EGC) to a metallic cable tray, ensuring electrical continuity and safety.

Purpose of the KGB Connection

The KGB connection is used to bond the EGC to the cable tray, which may itself serve as the grounding path in qualifying installations. This connection ensures that fault currents are safely conducted to ground, reducing the risk of electric shock and facilitating the operation of overcurrent protection devices . It also mechanically secures the EGC to the tray, preventing displacement under magnetic forces during fault conditions .

Installation Guidelines

• Clamp Placement: The EGC should be bonded to each or alternate cable tray sections using a KGB clamp. While not strictly required by the NEC, this is considered a best practice .
• Material Considerations: Avoid using bare copper conductors in aluminum trays to prevent electrolytic corrosion. Instead, use insulated conductors and remove insulation at bonding points with tin- or zinc-plated connectors .
• Tray Continuity: Cable trays must be electrically continuous. The KGB connection helps maintain this continuity across tray sections, even if mechanical continuity is not required .
• Sizing: The clamp and bonding conductor must meet the minimum cross-sectional area requirements based on the maximum fuse or breaker rating, as specified in NEC Table 392.60(A), .

Compliance with NEC

• NEC Section 318-3(c) allows the cable tray to serve as the EGC in qualifying facilities .
• NEC Section 250-96 requires all metallic cable trays to be grounded, regardless of whether they are used as the EGC .
• NEC Section 250-51 specifies that the grounding path must be permanent, electrically continuous, and capable of safely conducting fault currents .

Practical Tips

• Use insulated conductors for aluminum trays and remove insulation only at bonding points.
• Ensure mechanical stability of the clamp to prevent EGC displacement.
• Verify that the clamp material is compatible with the tray to avoid corrosion.
• Check that the cross-sectional area of the tray or conductor meets NEC requirements for the specific circuit rating . In summary, the KGB connection is a critical component in cable tray installations, providing both electrical safety and mechanical stability for the grounding system. Proper selection, placement, and bonding of the clamp ensure compliance with NEC standards and reliable operation of the electrical system.