(Boursier.com) — Enedis and Orange pool their strengths in order to modernize and improve the quality of connectivity on the island of Groix in Brittany by providing fiber optics and the latest technologies in the electrical network.
Started in mid-February, work to renew an old submarine cable that had been supplying the island of Groix with electricity for almost 40 years is continuing under the direction of Enedis, in partnership with Orange. The Orange subsidiary specializing in the deployment of submarine cables, Orange Marine, carried out the seabed preparation work and the laying of the cable at sea. Enedis and Orange ensure the technical connection operations on the landing stations on both sides of this 7.5 km long cable.
This last phase of the work is currently being completed. The landing of the cable is scheduled for May 5 in Groix and May 7 in Ploemeur. Commissioning is scheduled for the end of May, when the inhabitants of the Ile de Groix will continue to benefit from quality electricity and will switch to FTTH (Fiber To The Home) technology to access fiber.
Pooling of investments
With the aim of pooling investments and works, Enedis and Orange are joining their resources through an agreement. This renewal operation represents an investment cost of 4.5 ME, of which 87.5% is financed by Enedis and 12.5% by Orange.
The operation involves deploying a 7.5 km submarine cable between the island of Groix and the mainland at Ploemeur. This cable was designed in one piece and without junction. The Departmental Council of Morbihan had taken advantage of this opportunity to ask to associate the passage of optical fiber to equip the Ile de Groix with FTTH fiber.
Works in several phases, on land and at sea
The hybrid cable was manufactured in France and then assembled in Germany by the Prysmian/Silec group. The particularity of this cable is to contain 3 copper cables for current distribution (Enedis) and 48 optical fibers. Weighing 220 tonnes and measuring 7.5 km in one piece, it took 10 months to manufacture.
In order to prepare for the arrival of the cable, Enedis has been carrying out a 400 m long directional drilling in Groix since mid-February leading to the sea. This operation was carried out by a drill and assisted by divers. Of the 8 weeks of work, 15 days were devoted exclusively to drilling. A second drilling operation was carried out in mid-March in the town of Ploemeur (Lomener) in order to prepare the “landing” operations, that is to say connecting the electric cable to the mainland.
In order to prepare for the final works, one of Orange Marine’s cable ships, the Pierre de Fermat, transported the cable from Germany to Lorient at the end of April.
The last phase of the work now consists of laying the submarine cable, an operation which takes place mainly at sea and consists of positioning the cable in predefined places before laying it on the bottom and landing it on the Ploemeur and Groix sides. This cable will be connected to the 9 connection cabinets located in different sectors of the island. Each cabinet can serve 350 homes.
On Groix, the cable will arrive by a borehole from the top of the cliff and will come out to sea. In order to avoid a seagrass bed, protected species which develop only on sandy bottoms, an additional 200m of drilling has been carried out. This work necessitated an additional cost of approximately 500 kE. At the sea exit from the borehole, a natural system (bubble curtain) is implemented by divers in order to control the suspension of sedimentary residues.