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Puget Sound Energy transmission and infrastructure project

North Kitsap and Bainbridge Island electric system improvements

Fall 2014 project updates

  • For information about other projects on Bainbridge Island, visit
  • The Agate Pass tower replacement project was completed in late November. Site restoration and landscaping will take place in early December.
  • The Port Madison 115 kV transmission line upgrade and pole replacement project is anticipated to begin as early as summer 2015.

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Project map

Agate Pass tower replacement project overview

All of PSE’s electric power to Bainbridge Island is supplied via two medium-capacity power lines (called transmission lines) that cross Agate Pass at the same point. The power lines that span the pass are supported by two rusting towers, one on Bainbridge, and the other in unincorporated Kitsap County.

Built in the late 1960s the Agate Pass towers (called lattice towers) are reaching the end of their lifespan and need to be replaced. If they are not replaced soon, the towers - and the transmission lines they carry – could fail, causing widespread power outages for our customers in north Kitsap County and Bainbridge Island.

This summer, PSE began replacement of the two existing lattice towers with four new steel poles. Not only will the new poles be stronger than the existing lattice towers, but separating the two lines so they’re not on the same structure will improve system reliability. Construction is anticipated to be complete in October 2014. For more detailed construction updates, visit

Port Madison Tap 115 kV line and Foss Corner-Port Madison line upgrade overview

Once the Agate Pass project is completed, PSE will implement other upgrades to the area’s transmission system.

In 2015, as part of our Port Madison tap project, PSE will replace 115 kV transmission lines and poles in Kitsap County along Lemolo Shore Drive NE, across Agate Pass, and south to a substation at Day and Phelps Roads on Bainbridge Island (our Port Madison substation), (see map).

The 2016 Foss Corner-Port Madison 115 kV project will replace lines and poles in Kitsap County along NE Gunderson Road, Miller Bay Road, and Suquamish Way NE, and lines and poles along a different existing corridor south to our Port Madison substation.

These updates to the area’s system will further reduce the likelihood of power outages for customers in the north Kitsap, Suquamish and north Bainbridge Island areas. Upgrading these lines to new higher capacity wire will mean that in the unexpected event that one transmission line goes down, the other will be better able to pick up the load and continue to serve customers.

As part of the Port Madison tap project, we also will replace approximately 3.5 miles of existing overhead distribution line with specialized tree wire. Tree wire is a specially coated overhead wire that can withstand a tree limb falling into the line, significantly reducing the frequency of tree-related power outages. Portions of distribution line that will be upgraded with tree wire are located on the same poles as the transmission wires we’re upgrading as part of the Port Madison tap project (see map).

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.

What is a distribution line?

Distribution lines are critical links in the electrical system moving power from electrical substations through distribution transformers directly to homes or businesses. Unlike transmission lines, distribution lines typically carry less than 55 kV; PSE's distribution lines are typically 12.5 kV. Distribution lines can be installed both above and below ground.

What is tree wire?

Tree wire is a specially coated overhead wire, which prevents an electric short in the line (and subsequent outage) in the event a tree limb falls into a line. Tree wire is very useful at preventing outages in areas with many trees. Although it does not prevent outages caused by an entire tree falling into a line (if the tree is heavy enough to cause poles and wires to break,) it can significantly lower the frequency of power outages in your community.