N3 final pull through a success
The final section of the 7km, 90kV land cable that connects the Normandie 3 undersea cable to our network was successfully pulled through from South Hill to Gréve D’Azette this week.
This 1,000 metre section comprises of three individual conductors that are each pulled through pre-installed ducting separately. The pulling operation took four days and was completed in two stages, utilising the extra pit that had been excavated at Havre des Pas last week.
The installation involved blowing an initial lightweight rope through the ducting from South Hill to the intermediate pit at Havre des Pas using compressed air. A stronger rope was then used to install a steel bond before the cables themselves were pulled through by the wire with the aid of a powerful winch.
Once the first conductor reached Havre des Pas, the winch was moved to the joint bay by the Normandie Hotel at Gréve D’Azette and the whole process repeated. With the three individual cores installed at the bay, the jointers were able to start work jointing it to the previous section, a complex process that will take around ten days to complete before the excavation can be reinstated.
The final pull through of the power cables is another milestone in this 10-year project. The land cable works began in March 2013 when the first of the ducts started to be laid from Grouville to Mount Bingham. Work to install fibre optic cables, which run in ducts alongside the power cables, continues over the next few weeks.
The cable, which was manufactured by international specialists Prysmian in Gron, France, arrived in Jersey last December. It has since been pulled through in six sections, necessitating just five joints along the 7km route, plus the transition joint between land and sea cable at Long Beach car park. The installation team faced many challenges along the way, though the Normandie 3 Project as a whole remains ahead of schedule. Local photographer Andy Le Gresley captured this latest milestone in the project.
In France, the installation of the land cable is also nearing completion, with engineers expected to start work connecting it to the subsea cable this weekend.