Connecting jumpers between cable trays

Connecting jumper cable trays requires secure mechanical joining and proper bonding jumpers to ensure electrical continuity and system safety.

Mechanical Connection of Cable Trays

Splice Plates and Bolted Connections: Use flat metal splice plates with pre-drilled holes to join two tray sections in a straight line. Bolt the plates securely to each tray end using the recommended fasteners, ensuring a tight fit to maintain system stability and load support. This method is strong, reliable, and allows for future maintenance or adjustments.

Quick Connect Systems: Some manufacturers offer snap, slide, or twist-lock systems that reduce installation time and require minimal tools. These are ideal for large projects where speed is important, but they may only be compatible with specific brands. Angle or Junction Plates: For L, T, or cross-shaped connections, use specialized plates to route cables around corners or splits.

These plates ensure proper alignment and maintain structural integrity.

Installing Bonding Jumpers

Bonding jumpers are essential for maintaining electrical continuity, especially in painted, powder-coated, or expansion-joint-equipped trays. Follow these steps: Select the Correct Jumper: Use a flexible copper bonding jumper, typically 2 AWG soft-drawn tin-plated copper with flame-retardant insulation. Standard lengths are around 36 inches, but longer options are available for larger gaps.

Attachment Points: Bolt each lug of the jumper to a square hole at the end of the tray channel. Do not attach the jumper to splice plate bolts or pins; it must connect directly to the tray channel. Expansion Joints and Adjustable Splices: Always install jumpers across expansion splices or adjustable fittings to maintain continuity during movement or vibration.

Resistance Check: Ensure the connection resistance is below 0. 0003 ohms to comply with safety standards and pass inspections.

Grounding Considerations

All metallic cable trays should be grounded according to local electrical codes, regardless of whether they are used as the equipment grounding conductor (EGC),. Avoid placing bare copper conductors in aluminum trays to prevent electrolytic corrosion; use insulated conductors with exposed ends at bonding points. For stainless steel or aluminum trays, verify that the bonding jumper and fasteners are compatible with the material to prevent corrosion and ensure reliable grounding.

Best Practices

Plan for bonding jumpers during the ordering phase to avoid delays or inspection failures. Ensure all mechanical connections are tight and aligned to prevent sagging or cable damage. Use UL-rated splice plates when possible, but supplement with jumpers for painted or coated trays.

Regularly inspect connections for looseness, corrosion, or wear, especially in high-vibration environments. By following these steps, you can ensure that jumper cable trays are mechanically secure, electrically continuous, and compliant with safety standards, providing long-term stability and ease of maintenance.