For circular cables: (or use: Diameter² × 0.7854)

:

The most important rule:

| Nominal Conduit Size (mm) | Approx. Internal Diameter (mm) | Approx. Internal Area (mm²) | Max 40% Fill Area (mm²) | |---------------------------|--------------------------------|----------------------------|--------------------------| | 16 | 12.5 | 123 | 49 | | 20 | 16.1 | 203 | 81 | | 25 | 20.7 | 336 | 134 | | 32 | 26.6 | 556 | 222 | | 40 | 33.4 | 876 | 350 | | 50 | 42.4 | 1,412 | 565 |

Developing a feature for "Conduit Size for Cable" within the Australian market context requires strict adherence to Australian Standards (specifically and AS/NZS 3008 ).

return "recommended_size": "50mm+ or Multiple Conduits", "status": "Exceeds standard single conduit capacity"

These are for short, straight runs (under 10m, minimal bends). For long runs or multiple 90° bends, drop one size.

When in doubt, go one size larger. The cost of 32mm vs 25mm conduit is minor compared to a failed pull or non-compliant installation.