Making offshore connections

Array cables

The array cables will connect the wind turbines to each other and to the offshore substations. They’ll each measure between 650m and 1,200m in length. For Phase One, we’ll lay over 200km of array cabling . We’ll use specialised vessels and ROV’s to install the array cables.

Export cables

The export cables will run from the offshore substations to the onshore substation at Cleve Hill, where the power will be flowed into the national electricity network. The cables will be buried in trenches dug into the seabed using the special cable installation barge and plow, ‘Stemat Spirit’. As well as transporting electricity, the export cables will hold vital fibre optic wires that we’ll use to communicate remotely with the wind turbines. We’ll lay 220km of export cabling in Phase One and each of the four cables will be installed in one continuous length of over 50km.

Connecting the export cables

To connect the export cables to the onshore substation, we drilled through the seawall at Cleve Hill. We chose this option as it was the most unobtrusive method of installing the cables. Horizontal Directional Drilling (HDD) conduits were required, so we needed specialist plant and machinery on site to enable us to carry out the work. After the holes were drilled, we installed cable ducting and closed the holes until we are ready to pull each cable through.  The first export cable was installed towards the end of 2011; the remaining three cables will be installed this year.