NSTAR repairs failed undersea cable

On Saturday, NSTAR contractor Caldwell Marine wrapped up work in the middle of Vineyard Sound following the repair of an undersea power cable. — Photo by Mike Fletcher

Updated 9:50 am, Wednesday, August 28.

NSTAR contractors completed repair work Friday on a failed cable that carries electrical power under Vineyard Sound to Martha’s Vineyard. The location of the fault was in the shipping channel.

“With the damaged section of cable on the barge, Caldwell Marine workers cut back to where there was no sign of water infiltration and then spliced in a new piece,” NSTAR spokesman Mike Durand told The Times in an email Monday. “The cable repairs are complete and we returned the cable to service on Friday.”

In early July, one of four submarine NSTAR power cables from Falmouth to Martha’s Vineyard failed, causing brief power outages across the Island. Another cable is permanently out of service and due to be replaced.

With two of the Vineyard’s four electrical umbilical cords out, NSTAR added generators in order to meet increased summer demand.

Five permanent diesel generators owned by NRG Energy currently supplement power provided by NSTAR cables. Eight temporary generators were positioned around the Island before the start of the summer. Following the cable failure, seven more generators were added.

Two cables cross Vineyard Sound and land on shore at West Chop in Tisbury. Two other cables land at Eastville in Oak Bluffs.

NSTAR is currently in the process of installing an approximately 4.5-mile long hybrid fiber optic and electric cable across the sound. New utility poles that have generated considerable controversy will carry power from the new submarine cable.

This article was updated to clarify that NSTAR does not own the permanent generators that supplement power from NSTAR submarine cables.