NGE

NGE, a major French construction and civil engineering group, was contracted by Siemens Energy to carry out the civil engineering and infrastructure works for the Ar Merzher converter station — the French end of the 700 MW Celtic Interconnector at La Martyre in Finistère, Brittany. NGE has been on site since July 2023, delivering the full structural and ground-works package for the converter compound adjacent to RTE's existing 400 kV La Martyre substation. The scope spanned earthworks, 120 foundations, approximately 4,000 m² of raft slab and 4,300 m³ of concrete poured, plus 15 km of ducts and 7 km of copper cables installed to support the converter's electrical balance-of-plant. Three converter station buildings totalling around 5,000 m² were constructed under this scope, with structural completion achieved at end-2024 and overall infrastructure completion announced in April 2026 ahead of equipment commissioning. NGE delivered the works as Siemens Energy's local civil partner on behalf of project client RTE (Réseau de Transport d'Électricité), which co-developed the Celtic Interconnector with EirGrid as a cross-border HVDC link between Ireland and France. Main works completion is scheduled for May 2026, with energisation planned from June 2026 and full commissioning expected by 2028.