A portion of the energy transmitted through a cable is converted into heat and lost due to the conductor’s resistance. The amount of lost energy can be expressed with the formula:

Similarly, the resistance inside the cable also causes a voltage drop. The voltage drop between the two ends of the cable is expressed as:

It should be noted that the higher the conductor’s resistance inside the cable, the greater both the voltage drop and the energy loss.

The resistance of a wire is inversely proportional to its cross-sectional area. That is, provided the conductor material remains the same (copper if copper, aluminum if aluminum), as the cross-section increases, the resistance decreases proportionally. Therefore, when the cross-section increases, losses will be reduced.

In addition, the heat generation and voltage drop caused by high current draw will also decrease, contributing to the safety of the environment. As the cross-section increases, the current-carrying capacity of the cable also increases.

When selecting a cable, the potential and current required by the circuit to be supplied must be considered. The acceptable voltage drops between the power source and the circuit, the amount of energy loss in the cable, and the effects of these factors on operating costs and system safety must be calculated.