Correction Wizard for BS 7671 Cable Sizing BS 7671 cable sizing requires applying multiple derating factors depending on the installation method, ambient temperature, grouping, and soil conditions. These are spread across Tables 4B1 to 4B5 and 4C1 to 4C6, which can be complex and time-consuming to interpret. Errors in applying these factors can lead to incorrect cable sizes, safety risks, or costly oversizing. ELEK Cable Pro Web includes a built-in Correction Wizard that automates the selection