Wood poles are primarily used for transmission lines operating at what voltage?

Wood poles are commonly utilized for transmission lines operating at voltages of 345 kV or below due to their strength, availability, and cost-effectiveness. At these voltages, wood poles can adequately support the weight of the conductors and withstand environmental stresses such as wind and ice loading.

For transmission systems, materials are chosen based on the balance of mechanical strength, electrical insulation properties, and the economic feasibility of installation. Wood serves well in lower voltage applications because it has sufficient mechanical properties for the required span lengths and is capable of effectively isolating electrical components from the ground, given proper treatment to prevent decay and insect damage.

At voltages above 345 kV, alternative materials, such as steel or concrete, are typically preferred due to their ability to handle greater mechanical stresses and enhanced durability against environmental conditions. These materials can provide the necessary support for larger and heavier conductors used in higher voltage applications without the risk of mechanical failure or excessive sag. Thus, the preference for wood poles becomes limited to lower voltage standards.