Cable trays should be inserted at a 45-degree angle directly into the cable tray

Cable trays can be installed at a 45-degree angle by ensuring proper support, maintaining minimum bend radius, and following NEC and manufacturer guidelines.

Mechanical Considerations

When installing a cable tray at a 45-degree angle, it is essential to treat the sloped section as a diagonal in a right triangle, where the vertical elevation change and horizontal run define the slope. The centerline length of the tray along the slope can be calculated using the Pythagorean theorem, and the angle can be verified using the arctangent of the vertical offset divided by the horizontal run. For field bends, ensure that cut points are deburred and that any pre-made elbow fittings account for tangent lengths to maintain proper alignment.

Support and Stability

Structural hangers or supports should be placed within 24 inches (600 mm) of both ends of the 45-degree transition to maintain mechanical stability. For longer transitions or deeper trays, additional supports may be required, particularly at the top of bends or where multiple sections join. Shallow or narrow trays may require fewer supports, but always follow manufacturer recommendations for your specific tray type.

Bend Radius and Cable Safety

Maintain a minimum bend radius compatible with the thickest cable in the tray to prevent insulation damage. For example, ASP 45° cable trays provide a 24-inch bend radius for ease of coaxial cable installation. Ensure that the tray depth and width are suitable for the cable fill and ampacity requirements specified by NEC Article 392 and NEMA VE 2 standards.

Electrical and Code Compliance

Cable trays must be installed in accordance with NEC and CE codes, including proper bonding and grounding. Use UL-classified splice kits or no-splice supports to join tray sections, and remove any plastic masking to expose pre-galvanized wire for bonding. If the tray is not suitable as an equipment grounding conductor, provide a separate grounding means using approved conductors and connectors.

Always ensure that load ratings, cable fills, and ampacities are not exceeded.

Manufacturer Recommendations

Follow the specific manufacturer's installation instructions for angled trays. For example, U-style horizontal bends at 45 degrees typically have a 24-inch bend radius and standard tray heights of 4 inches, with optional depths available. Proper cutting, splicing, and support placement are critical to prevent cable damage and maintain system integrity.

By carefully calculating the slope, providing adequate support, maintaining minimum bend radius, and following code and manufacturer guidelines, a 45-degree cable tray installation can be both safe and efficient.