The most direct source of stress on power transmission towers is the conductors suspended above them. These conductors experience immense tension due to their own weight, icing, and wind forces. This tension is not evenly distributed across the tower but is concentrated at three key points: the conductor suspension point, the insulator string connection, and the end of the crossarm.
The design length of the crossarm (the horizontally extending portion) of the tower is directly related to the conductor arrangement. For example, the crossarms of double-circuit towers are typically longer because they need to support two sets of three-phase conductors simultaneously, with sufficient spacing between the conductors to prevent wind-induced discharge. The crossarm itself is not a solid structure but a lattice truss made of angle steel-a design that achieves innovative bending stiffness with minimal material usage.