Detailed Explanation of Cable Tray Large Elbow Fabrication

A large elbow in a cable tray system is fabricated to provide smooth directional changes for cable runs, ensuring mechanical support, proper bend radius, and compliance with load and safety standards.

Purpose of Large Elbows

Large elbows are used in cable tray systems to change the direction of cable runs, typically at 45°, 60°, or 90° angles, without compromising the integrity of the cables. They are essential in maintaining bend radius requirements, preventing cable damage, and ensuring smooth cable pulling during installation .

Material Selection

Cable tray elbows are fabricated from materials consistent with the main tray, such as galvanized steel, stainless steel, aluminum, or pultruded fiberglass. Material choice depends on environmental conditions, corrosion resistance, and mechanical strength. For example, stainless steel (AISI 316L) is preferred in corrosive environments, while aluminum offers lightweight and corrosion-resistant properties .

Fabrication Process

1. Cutting and Shaping: The tray sections are cut to the required length and angle. For large elbows, the side rails and bottom panels are bent using press brakes or roll forming machines to achieve the desired curvature.
2. Bending Radius: The bend radius must comply with cable manufacturer specifications to avoid cable stress. Typically, the radius is 1.5 to 2 times the tray width for large elbows .
3. Joining and Welding: Sections of the elbow are welded or bolted together. Welded joints provide higher strength, while bolted joints allow modular assembly and easier field adjustments.
4. Reinforcement: Large elbows may include gussets or stiffeners to maintain structural integrity under heavy cable loads.
5. Finishing: After fabrication, the elbow is galvanized, powder-coated, or otherwise treated to prevent corrosion and ensure durability .

Diagram Components

A typical large elbow fabrication diagram includes:

• Top and bottom views showing the bend angle and radius.
• Side elevation indicating tray width, height, and flange dimensions.
• Sectional views highlighting weld locations, stiffeners, and bolt holes.
• Dimensional annotations for cut lengths, bend radii, and flange extensions.
• Material specifications and finish notes.

Installation Considerations

• Ensure alignment with straight tray sections to maintain continuous cable support.
• Verify load ratings for the elbow, as large bends may carry concentrated cable weight.
• Maintain minimum bend radius to prevent cable insulation damage.
• Use support brackets at the elbow ends if the span is long or heavily loaded .

CAD and Technical Resources

For precise fabrication, CAD drawings and templates are often used. Manufacturers like ApexTray and Hubbell provide downloadable CAD files and technical manuals for large elbows, which include exact dimensions, bend angles, and assembly instructions . By following these guidelines, a large elbow can be fabricated to ensure mechanical stability, proper cable management, and compliance with electrical and safety standards.