Formula for a 45-degree bend in a 200-meter cable tray

For a 45-degree bend in a cable tray, the rise equals the offset distance, and the bend radius can be calculated as R = (W × C) / 2, where W is tray width and C is the bend coefficient (1.5 for 45°).

Basic Calculation

To create a 45-degree bend in a cable tray, you can use trigonometric relationships based on the offset distance and rise:

Bend Angle = arctan(Offset / Rise)

For a standard 45-degree bend, the rise equals the offset distance, simplifying the calculation. This ensures the tray changes direction smoothly without exceeding cable bend limits .

Bend Radius

The minimum bend radius is critical to prevent cable insulation damage. For metallic trays, it is typically 6–8 times the tray depth. A practical formula for the bend radius is:

R = (W × C) / 2

Where:

• W = tray width
• C = bend coefficient (1.5 for a 45° bend)

This ensures the bend is gradual enough for safe cable installation .

Cut-Out or Offset Sections

If you are making a field bend in a tray, you can calculate the cut-out section using the tray width and the number of bends required to achieve the total angle. For example, a 90° bend can be made with two 45° bends, and the cut-out length for each bend can be estimated as:

Cut-Out Section = Tray Width ÷ (90° ÷ Bend Angle)

For a 45° bend in a 600 mm tray: 600 ÷ (90 ÷ 45) = 300 mm .

Practical Considerations

• Ensure the bend radius meets or exceeds the cable manufacturer's minimum bend specifications.
• Consider tray material: hot-dip galvanized steel, aluminum, or stainless steel may require slight adjustments in bend allowance.
• For long runs like a 200-meter tray, plan bends at intervals to maintain structural integrity and ease of cable pulling.
• Use industry standards such as NEMA VE 1, IEC 61537, or BS EN 61537 for load ratings and bend compliance .

By applying these formulas and considerations, you can accurately design and implement a 45-degree bend in a cable tray while ensuring safety and compliance.