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Transmission Line Projects

Grid Upgrades to Support Reliable Service

Transmission lines link substations and other facilities to move electrical energy at high voltages over long distances.

TEP’s proposed transmission line projects are designed to enhance our local energy grid while preparing for our community’s future energy needs. Public outreach is an important part of TEP’s planning process. Click below to learn more about current projects.

Tucson Electric Power: Kino to DeMoss-Petrie 138 Kilovolt Transmission Line

Kino to DeMoss-Petrie 138 Kilovolt Transmission Line

TEP is developing plans to strengthen electric reliability for customers in central Tucson and help satisfy growing energy needs in our community.
Tucson Electric Power: Irvington-East Loop 138 Kilovolt (kV) Transmission Line

Irvington-East Loop 138 Kilovolt (kV) Transmission Line

TEP is preparing for construction of a new transmission line to help Davis-Monthan Air Force Base satisfy its energy resiliency requirements and improve electric reliability for customers.
Tucson Electric Power: Irvington to Kino 138-Kilovolt Transmission Line and Kino Substation Projects

Irvington to Kino 138-Kilovolt Transmission Line and Kino Substation Projects

TEP is building a new 138-kilovolt (kV) transmission line and substation and upgrading existing facilities in the area of South Kino Parkway and East 36th Street.
Tucson Electric Power: Sonoran Substation to Wilmot Energy Center 138 Kilovolt Transmission Line

Sonoran Substation to Wilmot Energy Center 138 Kilovolt Transmission Line

TEP is building a new 138-kilovolt (kV) substation, switchyard, and transmission line south of Tucson to support what will become our largest local community-scale solar array and battery storage system.

How does TEP determine where it needs to build new transmission lines?

TEP analyzes forecasted customer energy needs, energy efficiency programs, distributed generation and other factors to prepare its 10-Year Transmission Plan, which describes how TEP expects to maintain and improve transmission and other facilities over the next decade to meet the forecasted conditions and third-party interconnection requests.

To prepare the plan, TEP conducts an annual review of its existing Bulk Electric System as defined by the standards of the North American Electric Reliability Corporation (NERC). The review helps ensure TEP can plan for the system's maintenance and improvement in accordance with NERC standards. The plan describes:

  • Prospective transmission line projects above 115 kilovolts that TEP intends to initiate over the next decade to maintain reliability and meet customers future energy needs.
  • Upgrades necessary to maintain reliable service.
  • System locations where new transmission facilities may be required.

The plan is filed annually with the Arizona Corporation Commission, which must review and approve individual transmission line projects before construction can begin.

Why doesn't TEP develop transmission lines underground?

While TEP has installed some lower voltage distribution lines underground, our higher-voltage transmission and sub-transmission lines are installed overhead to support reliable, affordable service. Learn more.