IFA2 interconnector between Sellindge and France down over two months
Nov 2023Published 1 May 2026Responsible editor: Chief Editor
- Where
- Sellindge, Kent, United Kingdom to Les Mandarins, France
- What
- Unplanned outage on IFA2 high voltage direct current submarine interconnector
- Injuries
- None reported
- Cause
- Suspected cable fault
- Outcome
- Unavailable until at least February 2024
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Companies named in the reporting of this entry (being named is not a finding of fault): National Grid
What happened
In November 2023, National Grid issued a market transparency notification of an unplanned outage on the IFA2 (Interconnexion France Angleterre 2) high voltage direct current submarine interconnector, a link of around 1 GW between Sellindge, Kent, United Kingdom and Les Mandarins, France. The link was reported as unavailable until at least the start of February 2024 following a suspected cable fault, an expected outage of roughly two and a half months.
The link is one of several interconnectors across the English Channel crossing, and its unavailability over the winter heating demand period represented a meaningful reduction in cross border transfer capability between the two countries. Flows at the time were reported as predominantly imports on the interconnectors serving that region, so alternative transfer capacity was limited. No safety incident was reported in connection with the fault. The consequences reported were operational and commercial.
Contributing factors
The market notification characterised the immediate cause as a suspected cable fault. No further detail of the fault mechanism, such as insulation breakdown, mechanical damage from anchor or trawl interaction, or a manufacturing defect, was given in the public notification. The following is general industry context rather than reported detail: repair of a submarine HVDC cable normally requires fault location by electrical diagnostic methods over the full cable length, mobilisation of a specialist cable repair vessel equipped for the cable type and water depth, weather dependent lift, jointing and re-laying operations, and post repair commissioning testing. Fault location and vessel mobilisation each commonly take several weeks, which is broadly consistent with the outage duration indicated in the notification.
Lessons learned
- A submarine HVDC interconnector outage from a cable fault removes the full transfer rating for the repair period, so contingency plans must treat loss of the entire 1 GW block as credible.
- Repair of a submarine cable fault requires weeks for location and vessel mobilisation, so operators should plan on two to three months from detection to return to service.
- Winter import reliance means capacity assessments must include loss of one or more interconnectors for a full peak period.
More lessons on electrical protection and isolation, detection and monitoring, from every incident on the register.
Not yet known
- Exact fault mechanism and location
- Repair vessel mobilisation and jointing details
- Commercial cost of the outage
This entry is updated when these are reported. Get an alert for the next one like it.
Source
Published 2026-05-01. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.
