What size electrical jumper wire is needed for cable trays

Cable tray jumper wires are typically sized between 6 AWG and 2 AWG, depending on system voltage, current, and grounding requirements.

Typical Jumper Sizes

For standard cable tray grounding, earthing jumpers usually range from 6 AWG to 2 AWG using stranded copper conductors, with lengths from 12″ to 120″ depending on the tray layout and spacing between grounding points (Tuling Cable Tray Earthing Jumper). The jumper should be flexible enough to accommodate expansion joints or movement in the tray system.

NEC and Safety Considerations

According to NEC Article 250. 96(A), all metal raceways, cable trays, and non-current-carrying metal parts must be effectively bonded to ensure they can safely conduct any fault current likely to occur. When sizing a jumper wire, it is recommended to follow Table 250.

102 of the NEC, which bases the equipment grounding conductor size on the largest overcurrent protection device (OCPD) in the circuit. For example, a 30A circuit would typically require a #10 AWG copper grounding conductor.

Situations Requiring Jumpers

Painted or powder-coated trays: Coatings can block electrical continuity, so a copper bonding jumper is necessary. Expansion joints or high-vibration environments: Flexible jumpers ensure continuous grounding across moving sections. Non-UL-rated splice plates: If the tray connections are not UL-classified or cannot carry fault current safely, jumpers are required.

Installation Tips

Use stranded copper conductors for flexibility. Attach jumpers with compression lugs (1/4″ or 3/8″ studs) to ensure a solid connection. Ensure all bolts are tight and contact surfaces are free of paint or corrosion to maintain low resistance (