345kV-line completed under budget, on schedule in New England

345kV-line completed under budget, on schedule in New England

Three Phase Line Construction, Inc. developed a new 345kV overhead electric transmission line within an existing National Grid right of way (ROW) between the Tewksbury 22A Substation in Tewksbury, Mass., and Hudson, N.H., measuring approximately 14.6 miles. The utilities undertook the project in response to projected business growth in the area and the anticipated need by businesses for more energy. Three Phase relocated a number of existing assets within the right of way to accommodate the new 345kV line. As part of the relocation, crews moved a distribution line; foundations, suspension structures and wire for several 115kV-transmission lines as well as foundations for a 230kV- and 345kV line. National Grid, in partnership with Eversource, undertook the project to  bring local customers stronger, more reliable and cost-efficient energy service.


To complete the project, Three Phase installed 86 structures to support the construction of the new 345kV line. The new structures included H-frame suspension structures, self-supporting narrow based H-frame dead-end structures and self-supporting three-pole and single-pole structures. The average height for the structures is approximately 80 feet above grade. In relocating the existing lines, Three Phase erected another 87 structures featuring single- and double-insulator assemblies.


Construction began in October 2016

Construction completed in December 2017

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