What kind of pads should be used for cable tray supports

Use isolation or insulating pads made of materials like PVC or nylon to prevent galvanic corrosion and provide electrical separation between cable trays and their supports.

Purpose of Pads

Pads are used between cable trays and their mounting supports to: Prevent galvanic corrosion when dissimilar metals, such as aluminum trays on steel supports, are in contact. Provide electrical insulation to avoid unintended current paths. Reduce friction and mechanical wear between the tray and support.

Recommended MaterialsPVC Pads: Durable and effective for general isolation, especially for aluminum or steel trays. They are commonly used with hold-downs to ensure proper separation. Nylon Pads: Often part of complete insulating assemblies including bushes and washers.

Nylon provides excellent electrical insulation and corrosion resistance, suitable for stainless steel trays on galvanized or painted steel supports.

Design Considerations

Pads should be planar and sized to fit between the tray and support without interfering with fasteners. Some pads include fastener openings and isolation lips to accommodate different mounting methods, such as clamp-on or guide-on trays. Ensure the pad material is compatible with the tray and support metals to prevent chemical reactions.

Installation Tips

Fully encapsulate fixings with insulating components to maintain electrical separation. Use pads consistently across all support points to maintain uniform protection and mechanical stability. Verify that the pad thickness does not compromise the tray's load rating or alignment.

Summary

For cable tray supports, PVC or nylon isolation pads are recommended to prevent corrosion, provide electrical insulation, and reduce mechanical wear. Selection should consider the tray and support materials, mounting method, and environmental conditions to ensure long-term performance and safety.