The interconnection consists of four cables, two per link. This submarine and underground direct current dual connection will be 370 km in length, running between the Cubnezais substation (near Bordeaux, France) and the Gatika substation (near Bilbao, Spain). It will have two converter stations - one at each end of the link - that will convert the direct current to alternating current for connection to the electricity transmission grid of each country.

The link will connect to the Gatika electricity substation (in Bilbao) and the Cubnezais substation (to the north of Bordeaux). The submarine section will be approximately 280 km in length, from the Basque coast to the French Médoc coast.
The choice of route and placement of the cable on the sea floor will minimise the impact on maritime activities, especially fishing.

Submarine cable laying

Each cable will be placed on the sea bed with the help of a cable-laying ship. Generally-speaking, the cables will be buried for protection except where the ground is too hard, where they will be covered.

The interconnection will be connected to the Gatika substation, located to the north-east of Bilbao and 10 km from the Basque coast.

To do so, the existing Gatika-Lemoiz infrastructure comprising two 400 kV electricity power lines will be used. The route will leave the converter station to be built near the Gatika substation heading towards the Bay of Biscay area.

The process for presenting the document will be carried out in accordance with the Spanish Environmental Impact Assessment procedure, and the document will summarise the following: the characteristics and location of the project; the analysis of the potential impacts from the various alternatives for the converter and the line; and a territorial and environmental diagnosis of the effects caused by the project.

The link will connect to the Cubnezais electricity substation located to the north of Bordeaux. Hence, the underground section will run for less than 100 km from the right bank of the River Dordogne, passing beneath this river and the Garonne to reach the Aquitaine coast via the Médoc region, fully respecting the environment and human activity. Numerous factors must be considered in this coastal region, such as: environmental awareness, busy beaches, urban centres, awareness of coastline regression and the possibility of using infrastructures that already exist to sleave rapidly the coastline. The most suitable landfall points are located in the Médoc coast area.

The underground cable

Trench: Each trench will contain a pair of cables, and the two trenches will be separated by a minimum distance of 1 m Once work is completed, they will be covered over to hide them from sight.

Junctions: The underground cables will be installed in sections of approximately 1 km, each connected via a junction chamber. A similar, albeit slightly larger, device will be used to connect the submarine cables to the underground cables. These devices will be located far from the shore and will eventually be covered over because permanent access is not required, leaving them totally hidden from view.

The connection will link two alternating current systems via a submarine direct current line.
At each end of the connection, the converter stations will convert the direct current into alternating current for connection to the transmission grids of Spain and France.

The converter stations cover an area of approximately 5 ha and will be approximately 20 m high.