UK Cable Trunking Sizes & Capacity
Mini trunking and maxi trunking sizes with cable capacities, compartment options and installation guidance.
Mini Trunking Sizes
| Size W x D (mm) | Internal Area (mm²) | 45% Fill (mm²) | Approx. Cables (1.5 mm² T&E) |
|---|---|---|---|
| 16 x 16 | ~200 | ~90 | 1–2 |
| 25 x 16 | ~340 | ~153 | 2–3 |
| 38 x 16 | ~530 | ~238 | 3–5 |
| 38 x 25 | ~830 | ~373 | 5–7 |
| 40 x 25 | ~870 | ~392 | 5–8 |
Maxi Trunking Sizes
| Size W x D (mm) | Internal Area (mm²) | 45% Fill (mm²) | Typical Use |
|---|---|---|---|
| 50 x 50 | ~2,100 | ~945 | Small distribution runs |
| 75 x 50 | ~3,200 | ~1,440 | Medium distribution |
| 100 x 50 | ~4,400 | ~1,980 | Main distribution runs |
| 100 x 75 | ~6,700 | ~3,015 | Heavy distribution |
| 150 x 50 | ~6,600 | ~2,970 | Wide runs, compartmentalised |
| 150 x 75 | ~10,100 | ~4,545 | Large installations |
Cable Cross-Sectional Areas (for Fill Calculations)
| Cable | Overall Area (mm²) |
|---|---|
| 1.0 mm² T&E (3-core) | ~37 |
| 1.5 mm² T&E (3-core) | ~44 |
| 2.5 mm² T&E (3-core) | ~57 |
| 4.0 mm² T&E (3-core) | ~74 |
| 6.0 mm² T&E (3-core) | ~97 |
| Cat 6 data cable | ~28 |
Related Calculators
See the Conduit Sizes for conduit cable fill, or the UK Cable Sizes for cable current ratings.
How We Calculate This
Frequently Asked Questions
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Last updated: April 2026
All calculations are estimates. Verify with your supplier.