How to choose the right cable tray size for your project
Five steps from the Rovana Trade technical catalogue: tray, trunk or ladder, side height, cross-section area with 25% reserve, support spacing and finish.
Choosing the right cable tray size saves cost and protects the cables. These are the steps our technical team follows.
1. Tray, trunk or ladder?
- Perforated cable tray: suits most applications, makes cable laying easy, and the perforations let heat escape.
- Closed trunking: gives the best cable protection and suits cables with very low heat generation.
- Cable ladder: for power cables with higher heat generation, and for all cable types outdoors or in dusty areas.
2. Side height
Depends on the cable size and type. Our standard trays run from 25 to 100 mm high, and ladders from 75 to 150 mm.
3. Cross-section area
- Take each cable's area as a square: outer diameter × outer diameter.
- Add up the areas of all the cables.
- Add 25% reserve for future cables.
- The result is the tray cross-section. Divide by the chosen height to get the width.
Example: 10 cables of 4×35 mm², outer diameter about 25.1 mm.
| Step | Calculation |
|---|---|
| Area per cable | 25.1 × 25.1 = 630 mm² |
| Total for 10 cables | 6,300 mm² |
| + 25% reserve | 7,875 mm² |
| Tray width at 50 mm height | 7,875 ÷ 50 = 158 mm |
| Chosen size | 200 × 50 mm |
4. Support spacing
This is the distance between two support points. We recommend a standard spacing of 1.5 m; the loading diagram shows the deflection for each load.
5. Finish
Chosen by environment and location:
- Dry indoor areas: pre-galvanized to EN 10327
- Outdoor and industrial: hot-dip galvanized to BS EN ISO 1461
- Coastal and chemical: stainless steel
- Extra protection or a specific colour: electrostatic paint over galvanizing
Want us to size it with you? Send us your cable schedule and our technical team will recommend the size.