When several wires with small wire diameters are used to replace wires with large wire diameters, it is better to replace aluminum wires with copper wires as long as the sum of the cross-sectional areas of the wires with small wire diameters is not less than the sum of the cross-sectional areas of the replaced wires, as long as the current carrying capacity of the replaced copper wires is not less than that of the replaced aluminum wires. With the decrease of wire diameter, it is best to leave the production line. As for the data, it is in the electrician's manual or motor maintenance materials.