France’s Nexans has completed the first cable pull-in on the French side of the first interconnector between Ireland and France, following the initial campaign in Ireland. 

Developed by French and Irish transmission system operators (TSOs) Réseau de Transport d’Électricité (RTE) and EirGrid, the Celtic Interconnector will be the first direct electricity interconnection between the European continent and Ireland, spanning approximately 575 kilometers between La Martyre in Brittany, France, and East Cork, Ireland.

With a transmission capacity of 700 MW, the project will be able to supply power equivalent to the needs of approximately 450,000 homes. It is based on 320 kV HVDC technology and includes approximately 500 kilometers of offshore high-voltage cable, around 40 kilometers of underground cable in France, 35 kilometers in Ireland, and a 10-kilometer 400 kV HVAC connection to the Irish grid.

Marine cable laying operations for the project began in the summer of 2025 offshore Ireland, near Claycastle beach.

Nexans is responsible for the engineering, manufacturing and installation of the full cable system, with the high-voltage cables manufactured in Halden, Norway, using advanced extruded XLPE insulation technology, land cables produced in Charleroi, Belgium, and accessories manufactured in Cortaillod, Switzerland.

The pull-in operation was performed with support from the cable-laying vessel (CLV) Calypso.

“With the start of this construction phase on the French side, Réseau de transport d’électricité (RTE) is reaching a decisive milestone in the Celtic Interconnector project—the first electricity interconnection between continental Europe and Ireland—supported by the European Union and its agency CINEA,” said Régis Boigegrain, Managing Director of the Infrastructure Management Division and member of the Executive Board at RTE.

“This direct link strengthens security of supply, electrical solidarity and the integration of renewable energies at the heart of the energy transition. Through this project, RTE, together with its partner EirGrid, reaffirms its role as a builder of tomorrow’s power grid and as a partner of a more sovereign Europe.”

Furthermore, Siemens Energy and NGE have completed the construction of the Ar Merzher converter station in France, which will convert direct current transmitted via the submarine cable into alternating current for injection into the French electricity grid, and vice versa.

Main works are scheduled for completion in May, with energization planned from June and full commissioning expected by 2028.

“At Siemens Energy, we are proud to have completed the construction of the Ar Merzher converter station infrastructure with local partners on behalf of our client RTE. Throughout the construction phase, we met high quality standards to ensure the durability of the structure and enable the operation of all process equipment. We are now entering the final phase of the project, the commissioning of the equipment,” said Alexandre Pinson, Project Manager at Siemens Energy.

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