Southeast Wisconsin
Zone 5

Transmission system characteristics in Zone 5

ATC delivers power in Zone 5 with various transmission facilities including:

  • The southern portion of 345‑kV lines from Point Beach and Edgewater,
  • The Saukville, Arcadian, Granville, Oak Creek and Racine 345/138‑kV substations,
  • The transmission lines emanating from the Pleasant Prairie and Oak Creek power plants,
  • 230‑kV facilities near Milwaukee, and
  • A significant 138‑kV network in the Milwaukee area, a portion of which is underground.
Transmission system limitations in Zone 5

Transmission system performance issues in Zone 5 are generally related to heavy market flows from and to the south, resulting in high 345-kV and 138-kV line loadings and the need to monitor potential multiple contingency conditions.

Electric system overview

Increases expected in population, employment – Population in Zone 5 is projected to grow 0.5 percent annually between now and 2025, and employment is projected to grow 1.1 percent in the same time period. Waukesha County is projected to realize the largest increase in both population and employment.

Electricity usage growing

Peak electric demand typically occurs during the summer months. Large industrial loads in the Milwaukee metropolitan area, including Charter Steel and Miller Brewing, are among the largest electricity users in the zone.

Electric load is projected to grow approximately 0.7 percent annually through 2024.

Transmission projects in Zone 5

The most notable planned, proposed and provisional network projects and asset renewal projects in Zone 5, along with their projected year of completion and the factors driving the need for the projects, are listed below.

Zone 5 includes the counties of:
  • Kenosha , WI
  • Milwaukee , WI
  • Ozaukee , WI
  • Racine , WI
  • Washington , WI
  • Waukesha , WI
  • Waukesha , WI

Zone 5 Planned Projects

Project DescriptionIn-service yearNeed driver
Spring Valley-North Lake Geneva line 138‑kV construction2019Overloads and low voltages, provide network service

Zone 5 Proposed Projects

Project DescriptionIn-service yearNeed driver
Southeast Wisconsin-Northeastern Illinois Interface Project2020Overloads
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Zone 5 Asset Renewal Projects

Project DescriptionIn-service yearNeed driver
Merrill Hills-Summit 138‑kV line partial rebuild (portion of Quad Counties Electric Reliability project)2015Condition and performance
Mukwonago-Edgewood-St. Martins 138‑kV line rebuild2018Condition and performance