Why do conductors sag and sway?

The UVM Podcast, hosted by Stephen Cieslewicz and Nick Ferguson, has the goal to spread innovative ideas and knowledge in Utility Vegetation Management. The show aims to facilitate knowledge sharing within the industry and to raise awareness of the value of the profession with the wider public. Sponsored by LiveEO.


This episode features an interview with a Professional Engineer, Otto Lynch, President & CEO of Power Line Systems. Conductors can move during the course of a day under different electrical loading and weather scenarios, a phenomenon known as sag and sway, which is not always well understood. Sag and sway can have a major impact on vegetation management as the movement envelope needs to be taken into account to ensure that acceptable clearances between conductors and vegetation are maintained during all operating conditions. In today’s episode Otto provides a 101 on sag and sway and the impact this has on the work of UVM staff. They cover several topics in detail including:

  • What conductors are made of and why they expand and contract with temperature
  • How expansion and contraction affects tension and sag
  • Weather and electrical load variables that contribute to sag and sway (blow out)
  • Why knowing the conductor movement envelope is essential for UVM
  • Structure deflection in response to weather
  • The impact of ice storms on sag and sway, including conductor elongation
  • The role of PLS-CADD in modeling clearances
  • Thoughts on the future direction of technology
Click here to go to UVM Podcast’s homepage

Learn more about LiveEO’s Satellite-Based Vegetation Management Solution!