Conduit fill calculator

The tool totals the cross sectional areas, cable by cable, for the whole bundle. It divides that total by the internal area of the conduit to get the fill percent. It compares the fill with the permitted limit and suggests the smallest nominal conduit that fits the bundle.

The tool uses 50 percent for one cable, 33 percent for two cables and 40 percent for three or more. These are the space factors in AS/NZS 3000:2018 Appendix C, Paragraph C6.2. Tables C10 to C12 of the same Appendix give a maximum cable count method instead.

The nominal conduit size sets the internal area. The conductor size, the core count and the cable count set the cable area. At the same conductor size, a single core cable and a multicore cable have different overall diameters. The core choice therefore changes the result.

The tool uses the fill percentage method, not the cable count method. Overall diameters are derived from manufacturer data and vary by brand. Bends and draw in force are not modelled. The conduit size and the cable rows sit in the page address, so a link reproduces the bundle.