Multi-constraint LV cable selection: a review-oriented algorithm from tabulated ampacity to a complete design decision

A cable may satisfy current-carrying capacity and still fail protective-device coordination, voltage drop, short-circuit thermal withstand, automatic disconnection under the minimum fault current, or conductor-specific requirements. This report presents a review-oriented workflow that treats each criterion as a separate lower bound on conductor size, identifies the largest lower bound, then performs a closing verification on the selected standard size.

The method does not introduce new normative equations; its contribution is the ordering, integration and reporting of established checks so that the reason for the selected section remains visible. A worked 400 V three-phase feeder demonstrates the method using a synthetic but fully reproducible project dataset. Ampacity and overload coordination permit a 70 mm² copper phase conductor, short-circuit thermal withstand requires 95 mm², and voltage drop requires 120 mm²; the selected 120 mm² conductor therefore passes because the voltage-drop criterion governs.