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Greenwich Substation and Line Project

Eversource's application to build a new transmission line and substation in Greenwich was approved in November 2017.

Eversource and Greenwich officials worked together over the past year to re-examine the project’s need and scope to address the adequacy of the electric system serving the town of Greenwich.

In November 2017, the Connecticut Siting Council (CSC) voted to approve Eversource’s application to build a new transmission line and substation in Greenwich.

Project Design

Eversource is preparing to construct a new 115-kilovolt (kV) underground transmission line and build a new substation to enhance its ability to reliably serve our Greenwich customers.

The new line will extend 2.3 miles from Eversource’s existing Cos Cob Substation on Sound Shore Drive to the new substation at 290 Railroad Avenue. The new line will run mostly underground within town streets, including the streets in Bruce Park.

In addition, modifications will be made to equipment at the Cos Cob Substation. greenwich-map

Click to enlarge

Project Facts:

  • Underground route length: 2.3 miles
  • Location: Greenwich, Connecticut
  • Line voltage:115,000-volt (115-kV) transmission line
  • Substation: One new transmission-level substation and modifications to the existing Cos Cob Substation
  • Siting review by:The Connecticut Siting Council (CSC)

Estimated Timetable:

  • Municipal Consultation Filing (MCF): February 6, 2015
  • Connecticut Siting Council (CSC) Application filing: June 26, 2015
  • CSC Denial without Prejudice: May 13, 2016
  • Petition to reopen CSC Docket: May 5, 2017
  • CSC Public Hearing: July 13, 2017
  • CSC Approval: November 9, 2017
  • Development & Management Plan to CSC for Approval: First Quarter 2018
  • CSC Decision: Fourth Quarter 2017
  • Start of Construction:Mid-2018


On June 26, 2015, Eversource applied to the CSC for a Certificate of Environmental Compatibility and Public Need (Application) for the construction of the Greenwich Substation and Line Project. On May 13, 2016, the CSC voted to deny the project without prejudice.

On May 25, 2017, the CSC granted Eversource's Petition to reopen Docket 416 and on November 9, 2017 the CSC voted to approve the Greenwich Substation and Line Project.

CSC Development & Management Plans

In the first quarter of 2018, Eversource will submit the project’s construction plans, called the Development and Management Plans (D&M), to the CSC for approval. The D&M Plans include, among other things, conditions ordered by the CSC in its Decision, and a detailed site plan showing work areas, traffic management plans, and substation upgrades.


For more information about the Greenwich Substation and Line Project, send an email to or call 800-793-2202.