Conduit Fill
Check that a cable bundle fits in a conduit.
Questions
Each answer describes what this tool calculates. The result is a design aid. Verify against the current standard.
What does the conduit fill calculator do?
The tool adds the cross sectional area of every cable in the bundle. It divides that area 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.
What fill limit does the tool use?
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.
Which inputs matter most?
The nominal conduit size sets the internal area. The conductor size, the core count and the number of cables set the cable area. Single core and multicore cables of the same conductor size have different overall diameters, so the core choice changes the result.
What are the common gotchas?
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.