Whether you choose a free online tool, a custom spreadsheet, or commercial software, make sure it’s based on the (currently 2017 with 2019 amendments). Standards update—your tools should too.
Select cable type, insulation, and installation method (buried – Table 4 or 5). Base current for 70mm² Cu XLPE is around 235A.
Disclaimer: This post is for educational guidance. Always refer to the current AS/NZS 3008 standard and engage a qualified electrical engineer for final design decisions.
For a 10kA fault, 1s clearing time, 95mm² Cu easily withstands the temperature rise.