Cable tray jumper connection standard

Bonding jumpers are generally not required for standard metallic cable tray splice plates unless the tray is painted, has expansion joints, or is in a high-vibration environment.

General Guidelines

For standard rigid aluminum or galvanized steel splice plates, bonding jumpers are typically not necessary because the splice plates themselves provide sufficient electrical continuity between cable tray sections, meeting NEC grounding requirements (NEC 250 and 392.60) and NEMA standards . Properly installed UL-classified splice plates with tight bolted connections can safely carry fault currents without additional jumpers .

Situations Requiring Bonding Jumpers

Bonding jumpers should be installed in the following cases:

• Painted or powder-coated trays: Coatings can block electrical continuity, so a flexible copper jumper ensures proper grounding .
• Expansion joints: Trays that require movement need flexible jumpers to maintain continuity across joints .
• High-vibration environments: Braided copper jumpers are preferred to prevent breakage and maintain reliable grounding .
• Resistance concerns: If the connection resistance exceeds 0.0003 ohms, a jumper is recommended to ensure safety and compliance .

Installation Practices

• Bolting: A minimum of four bolts (two per side) is recommended for each splice plate to ensure tight contact and electrical continuity .
• Jumper type: Use UL-approved braided copper jumpers rather than solid wires, especially in areas subject to vibration .
• Testing: Verify electrical continuity and resistance to ensure compliance with NEC and project specifications.

Compliance and Safety

All metallic equipment enclosures and supports that may become energized must be bonded back to the system's equipment grounding conductor. Cable tray systems acting as grounding conductors must comply with NEC Article 250 and 392.60, ensuring personnel and facility safety . Properly installed splice plates alone are sufficient in most indoor applications using galvanized steel or aluminum, but jumpers provide additional assurance in special conditions .

Summary

• Standard metallic splice plates: Usually sufficient; jumpers not required.
• Painted, coated, or movable trays: Bonding jumpers required.
• High-vibration areas: Use flexible braided copper jumpers.
• Bolting: Minimum four bolts per splice plate.
• Compliance: Follow NEC 250/392.60 and NEMA VE-2 guidelines for grounding and bonding . By following these standards, cable tray systems maintain electrical continuity, ensure safety, and pass inspections efficiently.