Which factor directly affects the required conductor size?

The size of a conductor is primarily determined by the amount of current it needs to carry. When current flows through a conductor, it generates heat due to resistance, and if the current is too high for the conductor size, it can lead to overheating and potential damage. Therefore, the conductor must be sized appropriately to handle the maximum expected current safely without exceeding the temperature limits specified for the insulation.

While factors like voltage drop, distance, and temperature do play a role in the overall design of an electrical system, the current is the direct factor that dictates the necessary conductor size. Voltage drop is related to the distance and current but is a secondary consideration that affects system performance rather than conductor sizing directly. Temperature considerations are important too but mainly influence the material properties and the ratings of the conductor rather than establishing size requirements based solely on electrical current capacity.