Several environmental and mechanical factors cause the sag and tension to change over time, requiring careful design and calculation.

• Temperature: This is the most significant factor. As temperature increases, the conductor material expands, causing the conductor to lengthen. This reduces tension and increases sag. As temperature decreases, the conductor contracts, increasing tension and reducing sag.

• Wind and Ice Loading: High winds can exert a horizontal force on the conductor, increasing the overall tension and causing the conductor to sway. Ice buildup adds significant weight to the conductor, increasing both the sag and the vertical tension.

• Conductor Weight: The weight of the conductor itself is a primary driver of sag. Heavier conductors naturally have more sag for a given tension.

• Span Length: Sag is directly proportional to the square of the span length. Longer spans will have significantly more sag for the same tension compared to shorter spans.