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Puget Sound Energy substation project

Sedro-Woolley substation upgrades

Spring 2009 project completion
  • PSE completed the Sedro-Woolley major substation upgrades in May 2009

Project overview

To increase capacity and improve reliability of our electric system in Sedro-Woolley and surrounding areas of Skagit County, Puget Sound Energy in 2004 began a $20 million project to upgrade our Sedro-Woolley substation, located at 24972 Minkler Lake Rd. in Sedro-Woolley. PSE completed the project in May 2009, which involved:

Download full-size map

Project map (160 KB PDF)

  • Adding three 230 kilovolt (kV) circuit breakers to increase transmission reliability.
  • Installing a new 115 kV auxiliary bus to enable PSE to work on a line or transformer without taking the line or transformer out of service.
  • Replacing an aging transformer to increase capacity and improve reliability.
  • Replacing the substation's communications equipment and upgrading the system protection.
  • Constructing the new, five-mile Sedro-Woolley - Big Rock 115 kV transmission line to improve reliability to four substations in south Skagit County.


The electric grid works as one unit, so improvements to a substation or transmission line greatly improve the operation of the entire electric system. Recent upgrades to March Point substation have contributed to the increased capacity and improved reliability at the upgraded Sedro-Woolley substation and the surrounding area. Visit the March Point substation page to learn more about the substation upgrades.

What is a substation?

Substations are critical links in the electricity distribution system, containing utility circuit protection, voltage regulation, and equipment that steps down higher voltage to lower voltage. Before reaching homes and businesses, power is routed through our transmission system to a substation where it is changed to a lower voltage that can be utilized by customers.


What is a transmission line?

Transmission lines are key elements in the electrical distribution system. The lines safely transport high voltage electricity from power generation sources like dams and wind generating facilities to substations in local communities. Transmission normally takes place at voltages of 55 kV and higher.


Download the information

Download these PDF files for more detail on PSE's Sedro-Woolley substation project.
Project map (160 KB PDF)