The ElecLink interconnector will have a 1GW capacity, providing enough energy to power more than 1.65 million  households per year.

It will be the world’s first installation of a High Voltage Direct Current (HVDC) interconnector in a live rail tunnel environment.

Balfour’s share of the work is valued at £118m.

It will involve laying two 50km cables through the North tunnel and connecting them to converter stations in Northern France and Kent.

Prysmian Group will be responsible for the design and manufacture of the 320kV cabling and jointing services.

Balfour will use offsite jointing facilities in Calais and Folkestone to assemble 2.5km sections of cable and computer modelling to model the build in a virtual environment.

Ian Currie, Balfour Beatty’s Managing Director for Power Transmission and Distribution, said: “Balfour Beatty’s expertise as an international infrastructure group has enabled us to create innovative solutions to fulfil the requirements of this project.

“As global leaders we have been trusted with the first ever installation of a High Voltage Direct Current interconnector in a live rail tunnel environment.

“We will draw on our extensive experience of cable tunnel engineering projects, including the London Power Tunnels electricity superhighway, to deliver the project successfully.”

The project will provide employment for up to 300 people.