By performing year-round upgrades and maintenance to our local energy grid, TEP is prepared for the challenges of summer’s high temperatures and powerful thunderstorms.

Investments in our system helped to improve reliability in 2022 by reducing the average length power outages attributed to maintenance, equipment failure, weather and other factors. This measurement is known as the System Average Interruption Duration Index, or SAIDI.

Our SAIDI score improved to 61.8 minutes last year compared to 73.8 minutes in 2021 despite higher temperatures and increasing peak energy usage during the summer, which adds stress on our equipment.

In 2022 alone, TEP spent more than $290 million to improve power lines, poles, transformers and other transmission and distribution equipment and systems used to deliver service to customers every day.

“We work throughout the year to prepare for summer, when our customers’ energy needs are the greatest,” said David Wagner, TEP Director of Transmission & Distribution Line Construction and Metering. “During summer months, we increase the number of employees who work late shifts so that we can more quickly respond to late afternoon storm damage and other emergencies.”

TEP crews have completed several projects since last summer to improve service reliability for customers.

At the Canoa Ranch Substation, located south of Green Valley, substation crews installed two new, higher-capacity transformers to replace aging transformers that had been in service for more than 50 years. Insulation in both units showed signs of deterioration, and an analysis of maintenance history and outages indicated both units were nearing the end of their useful lives.

The approximately $5 million upgrade, completed in March, included installation of new switching equipment, fuses, and circuit breakers. Crews completed a similar $3 million upgrade at the Oro Valley Substation, located near North Oracle Road and North 1st Avenue, in February with installation of a new transformer and other equipment.

Since 2020, TEP has continued with accelerated replacement of power poles, using resistance testing to determine which poles are in greatest need of replacement. All distribution poles and pad-mounted equipment are visually inspected or tested every three years.

Crews replaced more than 100 power poles in the El Rio Acres neighborhood, located near West Grant Road and Interstate 10. Construction started in August 2022 and continued through March. The project was designed to improve the resiliency of distribution equipment that delivers service to customers in the area. TEP replaces about 1,200 poles a year due to storm or vehicle damage, routine maintenance, system upgrades and line relocations.

While some projects are completed and ready for summer, work continues on other system upgrades.

Over the last several months, crews have been hard at work installing power poles and overhead 138 kilovolt (kV) transmission lines to interconnect with the new Patriot Substation, located on the southwest corner of East Escalante and South Kolb roads. TEP is investing approximately $13 million to build the transmission line and approximately $21 million in the substation.

Patriot Substation, scheduled to be in-service later this summer, will help Davis-Monthan Air Force Base meet Department of Defense-mandated energy resiliency directives and strengthen electric reliability for residential and commercial customers in the area.

The new substation will replace an existing substation operating with a transformer and switchgear that have remained in service for more than 40 years. The new substation, along with planned improvements at other TEP substations, will support opportunities to retire other, lower-capacity 46 kV substations in the area.

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