At what voltages are sub-transmission lines energized?

Sub-transmission lines are typically energized at voltages that are higher than distribution voltages but lower than high-voltage transmission levels. The correct range for sub-transmission lines generally falls between 44 kV and 138 kV. These voltages are suitable for the transfer of electrical power from transmission facilities to substations that distribute electricity to end-users.

Sub-transmission lines serve as a bridge between the high-voltage transmission network and lower-voltage distribution systems, thereby ensuring efficient power flow and reducing transmission losses. Voltages like 69 kV and 115 kV are commonly used in sub-transmission applications, making the specified range accurate for this classification of lines.

The other options mention either much lower voltages, which are typically for distribution lines, or excessively high voltages used for long-distance transmission, which do not fit the criteria for sub-transmission. Thus, the selected choice accurately represents the voltage levels at which sub-transmission lines are energized.