What is the primary cause of line sagging in overhead power lines?

The primary cause of line sagging in overhead power lines is thermal expansion due to increased current flow. When electrical current passes through the conductors, it generates heat due to the inherent resistance of the materials. As the temperature of the conductors increases, the metal expands, causing the line to stretch and sag. This sagging effect is particularly pronounced during high-load conditions when more current is flowing through the wire, leading to greater thermal expansion.

Understanding this phenomenon is essential for linemen, as it can affect the clearance of power lines from the ground and surrounding structures. Additionally, this sagging can impact the mechanical integrity of the lines, making it crucial for linemen to monitor and manage conditions that lead to excess sagging, ensuring the safety and reliability of the power distribution system.

Other factors such as the weight of the line itself, improper installation techniques, and wind load effects can contribute to or exacerbate sagging but are not the primary cause. The dominant influence remains the thermal expansion due to current flow, making it vital knowledge for those working in the field.