Most sub-transmission circuits operating in the voltage range of 34.5 - 115kv are constructed on which type of wood poles?

Sub-transmission circuits that operate within the voltage range of 34.5 - 115 kV are typically constructed on single wood pole structures. This design is common because single wood poles are cost-effective, lightweight, and can support the required electrical load while maintaining adequate insulation from the ground.

Single wood pole structures are generally sufficient for these voltage levels due to their ability to provide effective support and stability in various environmental conditions. They are often used in situations where the electrical load does not require the extra support that might come with double or reinforced pole structures.

Double wood pole structures are more suited for higher load applications or where additional structural integrity is needed due to environmental factors, such as high wind or ice loading. Composite and reinforced wood structures also offer benefits for specialized applications, but they are less common for standard sub-transmission levels needed in typical distribution networks. Hence, the efficiency, practicality, and cost savings of single wood poles make them the preferred choice for this voltage range.