45-degree cable tray distance

The total length of a cable tray at a 45-degree angle is calculated by dividing the horizontal or vertical offset by the cosine or sine of the angle, or by using pre-fabricated 45° fittings for standard offsets.

Calculating Total Length

When a cable tray changes direction at a 45-degree angle, the total tray length along the slope is longer than the horizontal or vertical projection. The general approach is:

1. Identify the horizontal or vertical offset: Measure the distance the tray must move horizontally or vertically to reach the new alignment.
2. Use trigonometry: For a 45° angle, the tray length $L$ along the slope can be calculated as:

This formula applies whether the offset is vertical or horizontal, as the 45° angle creates equal horizontal and vertical components. 3. Two bends per offset: If the tray requires an offset to avoid obstacles, two 45° bends are typically used—one to move laterally and one to return parallel. The total tray section consumed is:

This ensures the tray maintains proper alignment and spacing for cables .

Practical Considerations

• Pre-fabricated fittings: For standard offsets (e.g., 6, 12, 18 inches at 45°), using pre-fabricated 45° fittings simplifies installation and ensures consistent angles .
• Field bending: Non-standard offsets may require field bending, which should be carefully measured to avoid misalignment.
• Support spacing: On sloped or angled sections, ensure supports are spaced according to the tray type and load to prevent sagging or excessive stress.
• Cable fill and heat dissipation: Angled sections may slightly affect cable fill calculations and airflow, so verify that the tray remains within NEC or manufacturer guidelines .

Example

If a tray must rise 500 mm vertically at a 45° angle:

For an offset requiring two bends, the total tray length would be:

This method ensures accurate material estimation and proper installation alignment.