CL&P and Long Island Power Authority (LIPA) are replacing seven fluid-filled transmission cables between Norwalk, CT and Northport, NY with three new solid-core cables that will be buried beneath the seabed of Long Island Sound. The projected in-sservice date is fall 2008. The original cables were removed in December, 2007 and January, 2008. The new cable has been installed on the Connecticut side and cable burial of the remaining 16 miles of cable in New York waters commenced the first week of May.

The replacement cables will significantly improve reliability of service to both states and reduce environmental impacts associated with fluid leaks from anchor drags and boat fishing dredges. LIPA and CL&P have jointly owned and operated the seven cables since 1969.

The facility consists of approximately 11 mi of three 138-kV electric transmission cables installed beneath the bed of the Long Island Sound. The cables will have the same  nominally rated transfer capability of 300 MW as the original cables with two of the three cables in service. The new cable is being buried beneath the seabed of Long Island Sound to prevent future problems associated with anchor dragging damage.

The cable manufacturer, Nexans, also did the cable installation using their cable laying ship, Skagerrak, shown in the photo in Long Island Sound waters.

According to a CL&P spokesman, the cable is considered a reliability asset to the grid. “At some peak times in the summer, we find the transfer of power to be critical to both sides, depending on which side is in need of greater capacity from outside.”