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Maineville Substation Expansion

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Transmission Investments

Reliability is a responsibility that Duke Energy Ohio takes very seriously. We are working on building a smarter energy future, which includes upgrading the electric transmission system in Warren County.

The Maineville Substation in Hamilton Township will be undergoing an expansion to support the community's growing energy needs.

Project Need

The substation expansion for an additional transformer will add capacity and support the reliability of the energy network, as well as meet regulatory standards to serve electricity to homes, schools, hospitals and businesses in the area.

Project Description

The construction involves the installation of a second 22.4 MVA transformer and associated equipment to change voltage levels between high transmission voltages and lower distribution voltages that carry energy to homes and businesses. A second driveway will be added to the substation. The substation fence will expand 30 feet by 200 feet on Duke Energy Ohio property — an anticipated 19 percent increase in the size of the substation.

This project includes adding a new 138-kilovolt (kV) steel electric transmission pole on Duke Energy property to the north of the substation. The new structure — a monopole 72.5 feet in height above ground — will connect to an existing 138-kV transmission line. This new structure is needed for the expansion of the substation and for connecting the transmission line to a new steel H-frame structure to be built inside the substation. The H-frame holds the force of the transmission line over longer distances between poles or, in this instance, on sharp angles along the route of the line. An additional 100 feet (0.02 miles) of 138-kV transmission line will be installed for this project.

Vegetation clearing for the project is planned for October 2020. Construction is planned for October 2020, with completion expected in December 2021.

In relation to this project, a notice to construct, operate and maintain this project is now pending before the Ohio Power Siting Board (OPSB) in Columbus, Ohio.

View the copy of the construction notice. A paper copy will be provided upon request. To obtain a paper copy, please contact 888.827.5116.

Benefits to the Community

  • Improves electrical system reliability
  • Maintains a robust system for supplying and delivering energy, which is integral to ensuring the continued economic growth and prosperity of the community
  • Improves power reliability for decades to come by strengthening the security of the energy grid


Have a question or comment? Email us at

or call 888.827.5116.