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CABLE TRAY SELECTION GUIDE
How Are Cable Load and Support Spacing Determined?
Cable-tray capacity is determined by evaluating cable weight, tray width, profile, sheet thickness, joint design and support spacing together. As support spacing increases, deflection rises and the same tray may carry a lower safe load.
Direct answer
Cable-tray capacity is determined by evaluating cable weight, tray width, profile, sheet thickness, joint design and support spacing together. As support spacing increases, deflection rises and the same tray may carry a lower safe load.
Technical review: MDES Engineering Technical TeamUpdated: 2026-08-05
How is total cable load calculated?
Calculate the mass per metre of every cable and add the tray, cover, divider and fittings. A suitable allowance should be included for future cable additions defined by the project.
Why does support spacing matter?
A longer span increases tray deflection. Capacity must be checked against the manufacturer's load table for the selected span, not by sheet thickness alone. Joints and fittings should be located near supports where practical.
Fill ratio and cable separation
The tray should not be packed completely. Space is required for heat dissipation, installation, maintenance and future expansion. Power, control and data cables should be separated where the project requires it.
Values to check together
| Parameter | Check |
|---|---|
| Cable load | Total kg/m |
| Support spacing | Span in the manufacturer's load table |
| Fill | Cable area and ventilation allowance |
| Environment | Corrosion and temperature |
Key points
- Include cable and tray-system weight.
- Read load and support span together.
- Allow for future cable capacity.
- Place bends and joints close to supports.
Frequently asked technical questions
Does thicker sheet always permit a longer support span?
No. Profile geometry, tray width, joints and tested load data also determine capacity.
Can a cable tray be filled completely?
It is not recommended; space is needed for ventilation, installation, maintenance and expansion.
Is the cover included in the load?
Yes. Covers, dividers and accessories must be included in the support-system load.
Which information is required for a cable tray quotation?
Specify the tray or ladder type, width and height, material and finish, total length, cable load, support spacing, fittings, project standard and delivery location. Final product selection and load capacity must be technically confirmed before ordering.
Technical references
- IEC 61537 cable management systems
- Project cable-load, fill-ratio and support-spacing calculations
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