Midtown Reliability Project

TEP projects future energy needs, including the impact of energy efficiency programs, distributed generation and other factors, to prepare its 10-Year Transmission Plan. The plan describes how we expect to maintain and improve transmission and other facilities over the next decade to satisfy anticipated energy needs and accommodate requests by third parties to interconnect with our system. The plan describes:

• Prospective transmission line projects above 115 kV 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.

It costs much more to build a transmission line underground than to build the same line overhead. The cost difference varies significantly by project but increases dramatically with higher voltages, which explains why many lower voltage lines are installed underground while higher-voltage transmission lines are not.   Underground lines also have higher maintenance costs. Because our costs are passed along to customers, TEP avoids unnecessary expenditures to help keep rates as affordable as possible.

The higher construction cost typically reflects civil engineering expenses, right-of-way acquisition, additional labor, and materials such as conduit, insulated wire and pull-boxes that are not required for overhead projects. Transmission lines conduct energy flows at higher amperages than distribution cables, generating far more excess heat that must be managed to avoid overloads. This requires the use of higher-cost conductors and other insulating infrastructure. Maintenance also costs more, takes more time and requires specialized training for utility workers as well as police, firefighters and others who might respond to an incident involving a high-voltage underground transmission line.

Electric and magnetic fields (EMFs) are part of our everyday environment and have both natural and human-made sources. The earth's magnetic field is one example of a naturally occurring EMF. Power lines and other electrically powered systems that light, cool and heat our homes and businesses, support communications and make other aspects of our modern lifestyle possible also emit EMFs.

For more than 30 years, scientists and researchers from universities, national laboratories, health agencies, the World Health Organization and other groups have conducted research activities into possible health effects of EMFs. According to this large body of peer-reviewed research, there are no confirmed health risks caused by exposure to low-level EMFs. The National Cancer Institute states “Extremely low-frequency EMFs include power lines, electrical wiring, and electrical appliances such as shavers, hair dryers, and electric blankets.”

For more information, please visit our Electric and Magnetic Fields information page.

No. In May 2023, City of Tucson voters rejected a proposal to fund portions of a new midtown transmission line through a fee included in a new franchise agreement between the city and TEP. That proposed line is now part of the Midtown Reliability Project, which will proceed independently from any future discussions about a new franchise agreement. TEP's franchise agreement, which extends through April 2026, authorizes use of public rights of way for our local energy grid.

Stakeholders submitted these questions at recent project open houses.

• Feb. 8, 2024
• Sept. 21, 2023
• Nov. 16, 2023