34.5 kV to 69 kV Transmission Line Rebuilds

Project Summary

Iowans are enjoying more reliable transmission service and additional electric system capacity with the completion of a long-term project that significantly improves the electric transmission grid in Iowa: the rebuild of the 34.5 kV system to 69 kV construction standards. These rebuilt 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.  

We all understand the challenges that result from system outages, ranging from the inconveniences in our homes to significant economic losses for manufacturers. The most significant benefit to the rebuilding of this system has been the dramatic decrease in transmission outages, which has significantly improved reliability for the utilities we serve, and ultimately, electric consumers. Through 2022, ITC Midwest reduced the total number of outages by 70% since 2007, based on a three-year rolling average.   

System capacity has more than doubled with the new rebuilds, which will support future economic growth for decades to come. The upgraded lines are providing additional back-up capability during planned and unplanned system outages. The rebuilds also provide improved system efficiency, which enhances operational flexibility and reduces overall system losses.

In all, 638 miles of new transmission lines have been rebuilt to 69 kV construction standards over the past 14 years.

Conversions are ongoing to operate the new lines at the higher 69 kV voltage, as connected utilities are able to convert. Through the end of 2021, 59 of 149 34.5 kV circuits have been converted to 69 kV operation or retired. The full benefits of the networked electric transmission system created by the 34.5 kV to 69 kV project will be realized when these conversions are complete.