Ensure cable can withstand fault current until protection operates. Adiabatic equation (IEC 60364-4-43):

How the cable is installed drastically changes its ability to dissipate heat. A cable clipped directly to a wall stays cooler than one buried in thermal insulation or pulled through a conduit.

Correct cable sizing follows a logical sequence: Designers must always consult local codes (IEC, NEC, BS 7671, AS/NZS 3008) and apply safety margins for reliability.