Electric Transmission

Ryan Manzo, Robert Bray, and Shane Sanders
From front, Ryan Manzo, manager of technical services; Robert Bray, system operations manager; and Shane Sanders, executive director of system operations, observe AEPCO’s transmission system from AzGT’s control room in Benson. They also keep an eye on other areas of the regional grid within the complex energy management system.

AEPCO transmits wholesale electric power from Apache Generating Station in Cochise, Arizona, to our six Member distribution co-ops, which serve members in southern Arizona, western New Mexico, northwestern Arizona and California. AEPCO operates and maintains:

  • 866 miles of transmission line owned all or in part by AEPCO
  • 36 substations reaching out from Apache Station across Arizona to the northwestern corner of the state
  • 30 telecommunications towers and an extensive fiber network used to communicate between AEPCO operations centers and substations, and Member cooperatives and customers

It takes a solid, reliable system to transmit power from our plant to our Member distribution electric co-ops, and on to their 420,000 member-consumers at the end of the line.

Transmission Partnerships Build Electric Reliability

Brandon Guinane, hot stick lineman apprentice, left, and Dustin Benavides, hot stick lineman, prepare to install new crossarm hardware on the Pantano-New Tucson 230-kilovolt line east of Tucson during a structure changeout project.
AzGT’s transmission crew upgrades the Oracle Junction Substation.

In recent years, AEPCO has built an impressive track record of successful transmission partnerships among transmission utilities and distribution cooperatives. This collaboraation is rooted in the knowledge that when the right partners come together, there is an opportunity for mutual benefits—reducing costs, improving reliability, and building a stronger system for a community or even an entire region.

  • AzGT is gathering public comments while planning a new Saguaro-Marana transmission line that will meet new demand in the Marana area served by Member Trico Electric Cooperative.  AzGT plans to purchase a transmission line that runs approximately seven miles from a neighboring utility’s existing Saguaro Substation to Trico EC’s planned Adonis Substation.  A neighboring utility is planning to locate a transmission line on the same poles for a portion of the route.  The public can participate in a virtual open house and submit comments at the Saguaro to Marana Transmission Line Project website. Learn more at the Current Transmission Projects page, call (520) 586-5252, or email
  • The Hilltop Interconnection involving Unisource Electric provides increased reliability and reduces downtime to many communities in Mohave County.
  • The Valencia Interconnection between AEPCO’s system and the Central Arizona Water Conservation District system provides improved reliability to both systems, as well as in Trico Electric Cooperative’s service territory.
  • AEPCO, APS and Sulphur Springs Valley Electric Cooperative (SSVEC) are working together to make major investments in new transmission facilities in Cochise County, Arizona, providing increased reliability to the AEPCO and APS transmission systems, and backup services to AEPCO Member SSVEC’s and APS’s distribution service territories. AEPCO’s portion of the Schieffelin-Tombstone Junction-Boothill Project was recently completed.

Having achieved lower project costs than our industry peers—and a reputation for quality design, construction, safety and timeliness—AEPCO has taken a lead role in most of these projects. This track record adds significant value to our partnerships and opens the door to future collaboration. These transmission partnerships enable AEPCO to resolve reliability concerns at the lowest cost and maximum benefit for all concerned.

We do extensive maintenance and perform upgrades to enhance system reliability whenever and wherever possible. Here, crews replace a component of one of the wooden structures that supports the Apache – Hayden 115 kV line, in a remote area east of San Manuel, Arizona.