( I_z \ge I_b ) AND ( I_z \ge I_n ).
If ( V_d > V_d(max) ), the conductor size increases by one step, and the algorithm repeats from Step 1. armoured cable size calculator
Many electricians and DIYers rely on standard heuristics. For example, "Use 2.5mm² for lights and 4.0mm² for sockets." ( I_z \ge I_b ) AND ( I_z \ge I_n )