Cable tray bends are calculated using the tray width, desired bend angle, and centerline measurements, with practical construction involving cutting, filing, and overlapping tray lips.

Calculating Bend Dimensions

For a flat 45° bend in a cable tray:

1. Determine the tray width (e.g., 100 mm).
2. Take the desired bend angle (e.g., 45°) and divide it by 2 to get the offset angle for marking (22.5° in this case).
3. Measure from the centerline of the tray to mark the points where the tray lip will be removed. For a 100 mm tray, this results in approximately 41.42 mm on each side of the centerline .
4. This formula can be applied to different tray widths and angles by adjusting the half-angle and corresponding side measurements. For a flat 90° bend:
5. Measure 2 3/4 of the tray width; half of this measurement is removed on either side of the centerline to create the bend .
6. Cut down the centerline carefully, flatten the tray lip at the bend point, and then bend the tray to the desired angle.
7. Use a gusset to reinforce the bend by cutting a piece of tray to fit the internal edges and bolting it in place .

Bend Radius Considerations

• Always respect the minimum bend radius of the cables to prevent damage. A common rule of thumb is 10 times the cable diameter, though this varies by cable type .
• Wider trays with small centerline radii can crowd the inner rail, reducing usable space, so plan bends to maintain proper cable fill .
• For multiple bends or offsets, remember that arc length and fill penalties stack, which may affect future cable additions .

Practical Construction Steps

1. Mark the tray according to the calculated measurements.
2. Remove the tray lip using a hand grinder or file, taking safety precautions .
3. Cut along the centerline without letting the tray fall open.
4. Flatten the lip at the bend point.
5. Bend the tray to the desired angle and secure with bolts.
6. Install a gusset if needed to maintain structural integrity . By combining these geometric calculations with careful physical construction, you can create precise bends in cable trays while maintaining cable integrity and tray capacity.