Cable trays are not connected with jumpers

Standard metallic cable tray splice plates often provide sufficient electrical continuity, so bonding jumpers are not always required.

Electrical Continuity and Safety

For standard rigid aluminum or galvanized steel cable tray splice plates, bonding jumpers are generally not necessary. Properly installed splice plates, when UL Classified and tightly bolted, provide a reliable electrical path between tray sections, meeting the National Electrical Code (NEC) requirements for grounding and bonding (NEC 250 and 392. 60) and ensuring personnel and facility safety.

Using additional bonding jumpers in these cases does not significantly improve safety and can increase material and labor costs.

Situations Requiring Bonding Jumpers

Bonding jumpers become necessary in specific conditions: Painted or powder-coated trays: Coatings can block electrical continuity, so a copper bonding jumper ensures a reliable path. Expansion joints or movement points: Flexible jumpers accommodate tray movement while maintaining grounding. Non-UL-rated or non-classified splice plates: If the splice plates are not tested for grounding, jumpers are required to maintain compliance.

High-vibration environments: Jumpers help prevent loosening of connections that could compromise continuity.

Installation Considerations

When bonding jumpers are used, they should be connected to dedicated grounding holes or bare metal surfaces, ensuring the serrated washer bites into the metal for reliable contact. Adequate slack must be provided to accommodate movement at expansion joints. For standard indoor installations using galvanized steel or aluminum trays without coatings or expansion joints, the splice plates alone are typically sufficient.

Summary

If your cable trays are standard, UL-rated, and properly bolted, you can safely omit bonding jumpers. However, painted trays, expansion joints, non-UL splice plates, or high-vibration areas require jumpers to maintain electrical continuity and code compliance. Always verify that the connection resistance is below 0.

0003 ohms to ensure safety and pass inspections.