Sag is essential for the safe and reliable operation of power lines. It serves several critical purposes:

• Reduces Tension: By allowing the conductor to curve, sag reduces the mechanical tension on the line and the supporting structures. Without sag, the conductor would be under extreme stress, making it susceptible to breaking, especially in cold weather when the conductor contracts.

• Thermal Expansion and Contraction: Sag provides a buffer for the conductor to expand and contract with temperature changes. As temperatures rise, the conductor expands and the sag increases. As temperatures fall, the conductor contracts and the sag decreases. This prevents excessive tension in cold conditions and maintains safe ground clearances in hot conditions.

• Wind and Ice Loads: Sag allows the line to withstand additional loads from wind and ice. The extra give in the line prevents it from snapping under the added weight and pressure.