When are lattice type towers utilized in transmission?

Lattice type towers are primarily utilized in high-voltage transmission lines, particularly for voltages of 345 kV and above, due to their structural advantages and cost-effectiveness. These towers provide sufficient strength to support the heavy loads associated with high-voltage conductors while also being relatively easy to construct and maintain.

The design of lattice towers allows them to withstand significant wind pressure and ice loading, which is vital for maintaining safety and reliability in diverse environmental conditions. Their open structure also minimizes wind resistance, which further enhances stability. Given these features, lattice towers are a preferred choice for extensive and demanding transmission networks, especially at higher voltage levels where efficiency and stability are paramount.

In contrast, using these towers at lower voltages, such as 100 kV or below, may not be necessary or economical, and other structures could suffice. The other options pertain to scenarios that do not typically involve lattice type towers; for example, temporary installations often utilize more lightweight and portable structures, while below-ground installations do not utilize towers at all as they involve underground cabling.