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Puget Sound Energy electric transmission line project

Cottage Brook - Moorlands 115 kV transmission line

Fall 2013 project complete
  • Construction took place in two phases. Phase 1 of the project began in May 2012 and was completed in early November 2012
  • Phase 2 of construction began in June 2013 and was completed in late 2013
Project overview

Puget Sound Energy’s existing 50-year-old 115 kilovolt transmission line between the Cottage Brook substation, 14401 188th Ave. NE in Woodinville, and the Moorlands substation, 8010 NE 185th St. in Kenmore, needed to be replaced. In addition to being old, the line was approaching capacity, putting it at risk of overloading in certain conditions. If the line were to overload, more than 56,000 customers served by 12 local substations in Woodinville, north Kirkland, Bothell, Kenmore and unincorporated King County were at risk of an outage.


To solve these problems, increase the reliability of the electric system, and help meet customers’ current and future demand for electricity in the area, PSE rebuilt the existing 7.6 mile 115 kV transmission line by installing higher-capacity wire, replaced many of the existing wood poles with new single wood poles, and added a new fiber-optic line. The fiber-optic line will help PSE monitor and coordinate our electric transmission system remotely through instantaneous communication and provide the ability to flip switches from a remote control room. Previously, PSE managed the existing transmission line through static data points, which required manual manipulation of switches to operate the system—a utility worker had to physically go out to the line to flip the switches.

Download full-size map

Project map

What is a transm​ission 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.

What is a fiber-optic line?

A fiber-optic line or optical fiber is a glass fiber that is designed to direct light along its length and is used for communication purposes within the electrical transmission system. The fiber-optic lines used in our electric system are small, half-inch in diameter lines. Fiber-optic is light, less expensive, and able to carry much more information at a quicker pace making your lights more reliable.

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.

Download information

Download these PDF files for more detail on PSE's Cottage Brook - Moorlands electric transmission project.

Construction notice, corrected April 2013
Project map, revised November 2012
Construction notice, May 2012
Project notice, April 2011
Fact sheet, May 2011
Project map