Factor Table !new!: Cable Derating

To correctly size a cable, the engineer must select a cable whose base ampacity ($I_base$) is high enough to withstand the reduction caused by the derating factors.

Although the load is only 75 Amps, the installer must use a 25 mm² cable. A 16 mm² cable would overheat under these specific installation conditions, despite being rated for currents higher than 75A in isolation. cable derating factor table