Which factor most significantly affects the tension in overhead power lines?

Environmental temperature changes are a critical factor influencing the tension in overhead power lines. As temperatures fluctuate, the materials used in the conductors, typically metals like aluminum or copper, expand when heated and contract when cooled. This thermal expansion and contraction affect the overall length of the power lines, leading to variations in tension.

When the temperature increases, the wires tend to elongate, which can decrease the tension in the line if the sag is not adjusted accordingly. Conversely, in colder temperatures, the contraction of the wires can lead to increased tension. Properly accounting for temperature changes is essential in line installation and maintenance to ensure safety, prevent sagging or excessive tension, and avoid undue stress on the poles and insulators.

The other factors, while they do have an influence on power line integrity, are generally less impactful in terms of tension changes due to varying environmental conditions. For instance, the diameter of the cable affects its strength and ability to carry current but does not directly influence how temperature affects tension. Similarly, the type of insulators and distance between poles are more relevant to line support and stability than to tensions resulting from temperature variations.