Cable tray crossarm specifications and sizes

Cable tray crossarms are typically sized based on tray width, load requirements, and material thickness, with standard spans ranging from 1.5 to 3 meters and side rail heights from 50 mm to 150 mm.

Standard Dimensions

Cable tray crossarms, also called support arms or brackets, are designed to hold the tray securely while maintaining proper spacing for cable fill and airflow. Key dimensions include:

• Span/Length: Crossarms usually span 1.5 m to 3 m between supports, depending on the tray type and load requirements .
• Side Rail Height: The vertical height of the crossarm or tray side rail typically ranges from 50 mm to 150 mm, influencing cable stacking capacity and heat dissipation .
• Material Thickness: Crossarms are commonly made from steel or aluminum, with thicknesses from 1.5 mm to 3 mm for light to medium loads, and up to 5 mm for heavy-duty applications .
• Rung/Support Spacing: For ladder trays, rungs welded to the crossarm are spaced 150 mm (6") to 300 mm (12"), affecting structural strength and cable support .

Design Considerations

• Load Capacity: Crossarm size must accommodate the weight of cables, trays, and any additional equipment. Ladder trays with I-beam crossarms provide 15–20% more strength than C-shaped channel crossarms .
• Tray Type Compatibility: Ladder, perforated, channel, and wire mesh trays require different crossarm designs. Ladder trays prioritize width and rung strength, while wire mesh trays rely on crossarm spacing and wire diameter for load support .
• Environmental Factors: Material selection and crossarm thickness should consider corrosion, temperature, and exposure conditions, especially in industrial or outdoor installations .
• Installation Flexibility: Crossarms should allow for adjustable height and angle to accommodate cable entry/exit points and maintain proper bend radius .

Practical Tip

When selecting a crossarm, start with the tray width and expected cable load, then choose a crossarm with sufficient span, side rail height, and material thickness to meet NEC, NEMA, or IEC standards. Proper sizing ensures structural stability, heat dissipation, and long-term reliability .