Cable tray jumper wires left and right

Bonding jumpers on cable trays are generally not required if standard metallic splice plates provide continuous electrical conductivity, but they are necessary for painted, coated, or movable sections.

Standard Cable Tray Splice Plates

For most rigid aluminum or steel cable trays, the bolted splice plates connecting the left and right side rails are designed to maintain electrical continuity. Properly installed, these plates meet NEC requirements for grounding and bonding, and additional copper jumpers are not required under normal conditions . Tests have shown that standard splice plates often perform better than separate bonding jumpers in terms of temperature rise and fault current handling .

When Jumpers Are Required

Bonding jumpers become necessary in certain situations:

• Painted or powder-coated trays: Coatings can block electrical continuity, so a flexible copper jumper ensures a reliable path .
• Expansion joints or movable sections: If the tray needs to accommodate thermal expansion or vibration, jumpers maintain continuity across gaps .
• Non-continuous tray sections: When trays are installed in separate segments, a jumper or external equipment grounding conductor (EGC) may be required to bond the sections together .

Installation Considerations

• Ensure tight bolting of splice plates with no paint or debris between metal surfaces. Use serrated nuts or star washers to improve contact .
• For high-vibration environments, jumpers provide additional safety and reduce the risk of loose connections .
• The size of the jumper should be based on the largest breaker feeding the tray if used as an EGC .

Practical Guidance

For typical indoor installations using galvanized steel or aluminum trays, if the splice plates are UL Classified and properly bolted, jumpers on the left and right sides are optional. However, for painted, coated, or movable trays, or where continuity is critical for inspection compliance, installing flexible copper jumpers is recommended to ensure safety and code compliance . In summary, evaluate the tray type, coating, and installation conditions to determine whether left and right side jumpers are necessary. Properly installed standard splice plates often suffice, but jumpers provide extra assurance in challenging conditions.