45-degree cable tray bends can be achieved using pre-fabricated fittings or field-fabricated bends, with the bend radius determined by cable size, tray width, and manufacturer recommendations.

Methods for 45-Degree Bends

Pre-fabricated fittings: Most manufacturers offer 45° flat or adjustable bends for light, medium, and heavy-duty trays. These fittings are available in various widths (50mm–900mm) and materials such as pre-galvanized steel, hot-dip galvanized steel, or stainless steel 316L, with closed or ventilated covers for protection and cable support (Metsec) . Field-fabricated bends: A 45° bend can be created by cutting the side rails of a straight tray section. The cut length is calculated using the formula: Cut = Tan(22.5°) × Tray Width. After cutting, the sections are bolted together to form the bend . NEC 392.18(A) allows field bends, but care must be taken to avoid sharp angles that could damage cables .

Bend Radius Considerations

The bend radius is critical to prevent cable damage and ensure ease of installation. While there is no universal NEC-specified minimum radius for cable trays, manufacturers often provide bends with radii such as 12", 24", 36", or 48" depending on tray width and cable type . The radius should accommodate the minimum bending radius of the largest cable in the tray, which can be referenced from standards like BS6622 or BS7870 for specific cable types . Key factors affecting bend radius:

• Tray width and type (ladder, ventilated, or solid bottom)
• Cable diameter and flexibility
• Available installation space
• Ease of cable pulling and future maintenance
• Cost and material constraints

Best Practices

• Use pre-fabricated bends whenever possible to maintain consistent radius and reduce installation effort.
• Ensure the bend radius is at least equal to the minimum bending radius of the largest cable.
• Avoid sharp angles in field-fabricated bends; smooth curves reduce stress on cables.
• Verify compliance with manufacturer guidelines and applicable standards such as NEMA VE-1 for metallic trays . By following these guidelines, a 45-degree cable tray bend can be safely installed while protecting cable integrity and ensuring compliance with industry standards.