During construction work to connect offshore wind farms, two offshore cables were damaged off the North Sea island of Norderney in the summer of 2026. In November, grid operator Amprion confirmed the incidents, which occurred both north and south of the island. The damage was caused by complications during cable laying and the process of pulling a line into a protective conduit. Both instances require extensive repairs; however, due to the storm surge season, these cannot be carried out until 2027. No information regarding the extent of the damage or the associated costs has been provided thus far. According to the company, the planned commissioning of the DolWin4 and BorWin4 grid connections in 2028 remains unchanged.
Image: Shutterstock
Offshore cables damaged during two construction operations
The first incident occurred north of Norderney back in June, when anchor piles from the cable-laying vessel “Barbarossa I” became embedded in the seabed. This caused complications during the work and resulted in damage to a cable. The construction crew ultimately had to sever the affected line and lay it down on the seabed in a controlled manner.
A separate operation south of the island also encountered difficulties. In this instance, a cable for the BorWin4 grid connection system was to be pulled through a pre-installed conduit. However, the line sustained damage during the pulling process, forcing the company to remove the affected section from the conduit. To transport it away, the workers cut the cable into several pieces.
Repair requires 1,100 meters of new cable
The repair processes for the two offshore cables differ significantly. North of Norderney, the damaged cable is to be recovered first. Technicians will then repair the damaged section using a joint sleeve before re-laying the line into the seabed. South of the island, however, such a repair will not suffice; there, Amprion must replace an approximately 1,100-meter-long section of cable and pull it through the existing conduit.
Repairs cannot begin immediately, however. In the Wadden Sea, construction work is restricted to narrow time windows to ensure the protection of birds and the coastline. Furthermore, the storm surge season makes operations involving specialized vessels considerably more difficult. Consequently, Amprion is postponing the repairs until 2027 and is coordinating further measures with the relevant authorities. The company has not yet disclosed the extent of the additional costs.
1.8 gigawatts of wind power depend on these grid connections
The damaged lines are part of two major infrastructure projects for German offshore wind energy. Once completed, DolWin4 and BorWin4 will collectively transport up to 1.8 gigawatts of wind power from the North Sea to the mainland. From the East Frisian coast, the connections will extend approximately 155 kilometers to Lingen in the Emsland region. These projects will provide additional transmission capacity for offshore wind farms as Germany continues to advance the expansion of offshore wind energy.
Despite the damage, Amprion is adhering to its original schedule. The grid operator has set a completion date of August 31, 2028, for DolWin4, and November 16, 2028, for BorWin4. The installation of further cable sections further offshore is already scheduled for 2027. However, the damaged lines must now also be repaired within this timeframe. Whether additional construction capacity is required for this has not been publicly quantified.
Additional repair requirements amid an already complex grid expansion
These two incidents illustrate the complexity involved in the technical grid connection of new wind farms. While wind turbines generate electricity far out at sea, specialized cables are required to transport this energy over long distances. The transition points—between the seabed, islands, and the mainland—are particularly challenging. Even isolated instances of damage can necessitate extensive recovery operations and the replacement of entire cable sections.
The current damage does not yet cause any immediate disruptions to the power supply, as the affected facilities are still under construction. From an economic perspective, however, the incident is significant. Additional repairs entail further expenditure on vessels, materials, and personnel. It remains unclear whether these costs will increase the overall budget or if they are covered by existing project reserves. What is certain, however, is that Amprion must repair two damaged cables before the new offshore grid connections can begin operation.
Author: Blackout News
Sources: NDR (04.11.26) – Welt (04.11.26) – ntv (04.11.26)