34.5 kV to 69 kV Line Rebuild and Conversion Project

34.5 kV to 69 kV Line Rebuild and Conversion Project

Since acquiring the transmission system, ITC Midwest has been following through on its commitment to improve electric transmission reliability in Iowa by upgrading the 34.5 kV system to 69 kV. Much of the existing system being rebuilt was constructed more than 60 years ago and has reached the end of its useful life.

These new transmission lines are part of ITC Midwest’s continuing efforts to serve the growing needs of customers and positions the system to support economic growth and development in communities across the region. The upgraded lines are improving efficiency, reducing transmission outages, increasing the system’s capacity, and providing additional back-up capability during planned and unplanned outages. This project also responds to growing customer demands for reliability, with better lightning protection to reduce the incidence of lightning-caused outages.  

There are two phases to each upgrade: rebuilds and conversions.  Rebuilds typically include removing the existing poles and lines, then reconstructing each line to modern 69 kV construction standards to better withstand Iowa weather.  Conversions entail the system changes required to operate the new lines at the higher 69 kV voltage.

ITC has made significant progress in the rebuilds, completing approximately 520 miles since 2008, with about 120 miles left to finish.  ITC is on schedule to have the rebuilds completed by 2021. Conversions are currently ongoing, as connected utilities and independent power producers are able to convert, and will continue to take place after the rebuilds are done. Through the end of 2018, ITC had converted 47 of 149 34.5 kV circuits to 69 kV operation, or retired them. All the 34.5 kV to 69 kV conversions are slated to be completed by 2029.

The 34.5 kV rebuilds completed over the past decade have contributed to the significant improvement in system reliability in the ITC Midwest system. Through 2019, ITC Midwest has reduced the number of outages by 63% since acquiring the system in 2007, based on a three-year rolling average. The outage reduction improved from the previous three-year average of 60% and the 2017 average of 59%.

Beyond the capital expense of replacing or rebuilding hundreds of miles of lines, the 34.5 kV rebuild program has also required managing the regulatory process and working closely with hundreds of landowners. Just as critical, ITC has worked closely with community leaders and customer utilities to ensure the coordination of investments to maximize the benefits and minimize the expenses to both ITC and other utilities.


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