The outage means there will be less overall capacity available to the UK’s power system this winter which is predicted to be one of the tightest in years.
“We experienced a trip of the IFA interconnector on the morning of Sunday 20 November,” National Grid said in a statement. “After further investigation, the fault has been identified and we can confirm that four of IFA’s eight cables have been damaged. This will result in a reduction of IFA’s maximum capacity to 1000MW until the end of February 2017.
“Investigations are ongoing and teams on both sides of the channel are working to restore IFA to full availability. We will issue regular updates regarding progress.”
A spokesman said the company was investigating whether the damage was caused by a ship’s anchor dragging along the sea floor during Storm Angus.
In its latest Winter Outlook in October, National Grid predicted a capacity margin of 1.1 per cent during peak hours this winter, rising to 6.6 per cent once of the Supplemental Balancing Reserve. However, both these figures assumed 2GW of net imports from continental Europe, partly through the damaged French interconnector.