Cable tray jumper diameter

Cable tray jumpers are typically sized between 6 AWG and 2 AWG copper, with the exact size determined by system voltage, current rating, and NEC requirements.

Jumper Sizing Guidelines

The size of a cable tray jumper should comply with the National Electrical Code (NEC), particularly Section 250. 64(E)(3), which states that a bonding jumper must be the same size as or larger than the enclosed grounding electrode conductor to ensure proper grounding and safety. For industrial applications, jumpers sized 3/0 AWG or larger may be required depending on the system's current rating.

NE

C Table 250-95 can also be used to determine the minimum conductor size based on the highest fuse or breaker rating in the tray system.

Typical Jumper Sizes and Materials

In practice, earthing jumpers for cable trays are commonly made of stranded copper and range from 6 AWG to 2 AWG, with lengths from 12 inches to 120 inches depending on the installation layout. Aluminum conductors may be used in moisture-prone environments to prevent galvanic corrosion when bonding aluminum trays.

Installation Considerations

Connection Points: Use 2-hole compression lugs with 1/4″ or 3/8″ studs for secure attachment to the tray and grounding points.

Painted or Powder-

Coated Trays: Additional copper jumpers are recommended because paint can block electrical continuity. Expansion Joints: Flexible jumpers are required to maintain grounding across moving sections. Number of Bolts: Typically, four bolts per joint (two on each side) ensure a solid electrical connection.

Resistance Check: Ensure connection resistance is below 0. 0003 ohms to pass inspection and maintain safety.

Summary

To select the correct cable tray jumper: Determine the grounding conductor size per NEC Table 250-95. Choose a copper or aluminum jumper equal to or larger than the grounding conductor. Adjust length to span the tray sections, including expansion joints.

Ensure secure connections with proper lugs and bolts, and verify low resistance. Following these guidelines ensures electrical continuity, compliance with NEC, and safe grounding of the cable tray system.