Cable tray support crossarms are typically U- or L-shaped steel members with thicknesses of 2.5–4 mm, lengths matching tray width (300–500 mm), and spacing of 500–1000 mm, designed to meet static and dynamic load requirements.

Material and Construction

Crossarms are generally made from Q235 low-carbon steel and are hot-dip galvanized for corrosion protection, following GB/T 13912-2022 standards . The galvanization process includes cooling and passivation to seal zinc coating pores, ensuring durability in industrial environments .

Cross-Section and Thickness

• Shapes: U-shaped or L-shaped cross-sections .
• Thickness: Classified into 2.5 mm, 3 mm, and 4 mm, depending on the load level .
• Flange Width (for heavy loads): 60–80 mm for stiffened crossarms in high-load scenarios .

Dimensions

• Length: Matches the cable tray width, commonly 300 mm, 400 mm, or 500 mm .
• Spacing: Crossarms are typically installed at 500–1000 mm intervals along the tray span .
• Deflection Limit: Maximum sag should not exceed L/200, e.g., 5 mm for a 1000 mm span .

Load Capacities

• Light-duty trays (control cables): 50 N/m .
• Power cable trays: 150–200 N/m .
• Heavy industrial loads: Over 300 N/m, requiring stiffened crossarms .
• NEMA-rated spans: Individual rungs support 200 lb (90.7 kg) concentrated load with a 1.5 safety factor .

Design Considerations

• Crossarms must accommodate both static and dynamic loads .
• For continuous spans, deflection is reduced by up to 50% .
• Compliance with GB 50217, NEC, NEMA VE 1, and ASTM standards ensures structural integrity and safety .
• Crossarms are bolted to tray side connectors, forming secure support nodes .

Summary

When selecting or designing cable tray crossarms, consider material, shape, thickness, length, spacing, load rating, and compliance with standards. Proper sizing ensures structural stability, minimal deflection, and long-term reliability in industrial, commercial, or heavy-duty installations .