When determining the specification of wire and cable (conductor cross-section), the selection conditions such as heat generation, voltage loss, economic current density, and mechanical strength should generally be considered.
According to experience, the low-voltage power line has a large load current, so it is generally selected according to the heating conditions, and then the voltage loss and mechanical strength are checked; the low-voltage lighting line has a higher voltage level, and the voltage loss can be adjusted according to the allowable voltage loss condition. Select the cross-section, and then check the heating conditions and mechanical strength; for high-voltage lines, first select the cross-section according to the economic current density, and then check the heating conditions and allowable voltage losses; and the high-voltage overhead lines should also check the mechanical strength. If the user has no experience, the relevant professional unit or person should be consulted.