Specifications for use of cable tray supports

Cable tray supports are designed to provide mechanical stability, maintain proper spacing, and ensure safe routing of electrical cables, with specifications determined by load, span, material, and installation method.

Support Elements and Types

Cable tray supports include wall brackets, suspended supports, center suspensions, and trapeze hangers, which connect the tray to ceilings, walls, floors, or structural beams (OBO CMS), . Common support methods are:

• Trapeze hangers: Used for ceiling suspensions, supporting long runs of cable trays.
• Cantilever wall brackets: Mounted directly to walls for vertical or horizontal runs.
• Center suspensions: Provide support at midpoints for long spans to prevent sagging.

Material and Finish

Supports are typically made from steel, aluminum, or fiberglass-reinforced plastic (FRP) depending on environmental conditions (ABB, Legrand), :

• Steel: High strength, suitable for heavy loads; may be galvanized or powder-coated for corrosion resistance.
• Aluminum: Lightweight, excellent corrosion resistance due to natural oxide layer.
• FRP: Non-conductive, corrosion-resistant, ideal for chemical or high-moisture environments.

Load Capacity and Support Span

The load-carrying capacity of a cable tray depends on the tray type, material, and support spacing. Manufacturers provide load charts to determine the maximum weight per span. Typical rung spacing for ladder trays is 6–9 inches (150–230 mm) to support cables and maintain minimum bend radius (ABB), . Support spans are calculated based on:

• Total anticipated cable weight
• Tray type (ladder, ventilated trough, solid bottom)
• Environmental factors (vibration, wind, seismic activity)

Installation Considerations

• Mounting elements such as plates or clamps are used to attach junction boxes or devices to the tray (OBO CMS), .
• Spacing and alignment must prevent sagging and maintain proper cable bend radius.
• Compliance with standards: NEC Article 392 and NEMA VE 1 specify installation, load, and material requirements to ensure safety and reliability (ExpertCE), .
• Environmental factors: Supports must account for water, oil, corrosive substances, and temperature variations, though external mechanical forces like snow or wind are typically considered separately (OBO CMS), .

Summary

Cable tray supports are critical for mechanical stability, safety, and compliance. Proper selection involves:

1. Choosing the correct support type for the installation environment.
2. Selecting material and finish based on corrosion and load requirements.
3. Calculating support spans and load capacity using manufacturer charts.
4. Ensuring installation follows NEC and NEMA standards for safe and reliable cable management.