Phoenix, Ariz. -  The Arizona Corporation Commission held its Fourteenth Biennial Transmission Assessment Workshop on Thursday, July 16, 2026 to review the current status and future needs of Arizona’s transmission grid system.  Each electric utility performed testing of their transmission system to identify any areas of reliability concern utilizing a set of reliability criteria identified by the Commission.  The criteria includes ensuring thermal loadings and voltages remain within allowable normal and emergency limits; ensuring there are no voltage deviations outside of required guidelines; and confirming there are sufficient reactive power margins on their systems.

This year, the Commission requested the utilities submit a detailed Confidential Critical Infrastructure Information report - a complete risk mapping of their transmission systems that identifies areas of congestion and load growth pockets. The Commission will use the information to review and assess the transmission grid as a whole when considering the numerous interconnection requests that are being submitted for the Commission's approval.

“This year’s workshop was very comprehensive and much improved over prior workshops," said Vice Chair Rachel Walden.  "I want to recognize our utilities for the detailed work and effort that went into testing their systems.  I want to especially recognize and thank Tucson Electric Power for chairing the Southwest Area Transmission (“SWAT”) Task Force composed of all of our utilities that own and operate Arizona’s collective transmission grid.” 

The Task Force assessed the comprehensive list of transmission projects planned over the next ten years to identify any critical failures that might result if one or more of the projects was delayed or not completed on time.  

“Ensuring the reliability of our transmission grid is paramount, and as the result of the presentations provided to the Commission, I am confident that APS, TEP, UNSE, SRP and AEPCO have taken all the necessary and responsible actions to ensure Arizona’s grid continues to be in the top quartile of the most reliable grids in the country," said Vice Chair Walden.

For further information, contact Walden-Web@azcc.gov.