Why are voltages and clearances in substations different from those in distribution lines?

The correct answer highlights the operational procedures in substations that necessitate different voltage levels and clearances. Substations are designed to handle high voltage power and interconnect various transmission lines, which necessitates unique safety protocols. When maintenance or repairs are needed, it may be possible to partially de-energize certain circuits to maintain power to critical areas. This partial de-energization affects how voltages and clearances are managed because all equipment may not be fully turned off, requiring higher clearances to ensure safety and prevent accidental contact with energized components.

Higher voltages present in substations are primarily a function of transmission requirements and not solely related to the equipment standards or types present. While the presence of diverse electrical equipment is true, it’s the maintenance strategy of being able to work on live systems that shapes the voltage and clearance requirements most directly. Additionally, while vegetation can influence clearance requirements, it's not the primary reason for the differences in voltage levels and clearances between substations and distribution lines.