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Seacoast Reliability Project

To help ensure that the New Hampshire Seacoast Region can continue to grow and thrive, Eversource is building the Seacoast Reliability Project, a new transmission line connecting two existing substations.

The project includes a new 115-kilovolt (kV) transmission line extending approximately 13 miles between substations in Madbury and Portsmouth, N.H., along with associated substation upgrades. 


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Once complete, the project will help improve the transmission system in the Seacoast area so that our customers will have reliable electric power to meet their current and growing energy needs. It will also ensure that the area's electric grid conforms to national and regional reliability standards.

Eversource will invest more than $84 million in New Hampshire to bolster the regional infrastructure. Though the project will result in direct benefits for New Hampshire communities, residents and businesses ― including the enhanced system reliability for customers, creation of local jobs, and property tax payments in host communities ― the cost of the project will be paid by all electric customers in New England.

See the one-page Seacoast Reliability Project information sheet for more details. 

New Hampshire Site Evaluation Committee

For an electric transmission line project, such as the Seacoast Reliability Project, the New Hampshire Site Evaluation Committee (SEC) Application Filing is part of the siting regulatory view process, as defined by the New Hampshire state statutes. On December 10, 2018, the SEC voted unanimously to approve the construction of the project. On January 31, 2019, the SEC issued its written order, reaffirming its oral approval. The committee’s approval follows a series of public information sessions and public hearings in Concord and in the communities that will host the new 115-kV transmission line.

Estimated Timetable (subject to change):

  • Application filing with the SEC: April 12, 2016
  • SEC verbal decision to approve the project with conditions: December 10, 2018
  • SEC written order and conditions of approval: January 31, 2019
  • Community meetings for construction overview: March/April 2019 
  • Start of construction: Second Quarter 2019
  • Project completion: This project will take approximately one year to construct.

Construction Updates

Eversource is committed to updating and proactively communicating with neighbors, businesses and all community members about project activities and will continue this outreach throughout the construction process. A dedicated outreach team will provide notifications prior to the start of work and perform onsite meetings by request.

The sections below also feature construction updates for each town.

  • Construction updates expected to begin in 2019.
  • Construction updates expected to begin in 2019.
  • Construction updates expected to begin in 2019.
  • Construction updates expected to begin in 2019.
  • Construction updates expected to begin in 2019.
  • Construction updates expected to begin in 2019.

Contact Information

If you have questions or concerns about the Seacoast Reliability Project, please send an email to or call 1-888-926-5334.