How To Size A Cable

The cable must be protected by a circuit breaker or fuse. The rating of the protective device ($I_n$) must be selected such that: $$I_n \geq I_b$$ The chosen cable must be capable of carrying this current continuously without exceeding its temperature limits.

During a short circuit, heat is generated faster than it can dissipate (adiabatic process). The cable must survive until protection clears the fault. how to size a cable

The cable must be able to withstand the thermal energy of a short circuit fault until the protective device trips. The cable must be protected by a circuit breaker or fuse

If the selected cable size from Step 5 is smaller than $S$, the cable size must be increased. the cable size must be increased.