A catastrophic failure of the subsea cable between Skye and the Isle of Harris was responsible for a massive power cut which hit everyone in Lewis and Harris on Friday (16 October), according to Scottish and Southern Electricity Networks (SSEN).

A spokesperson for SSEN said today (Monday 19 October) that the significant fault means that all 17,774 properties in the two islands are now being powered by the diesel-fired turbines at Battery Point power station – and that this will continue for ‘the foreseeable future’.

The undersea cable break means that the only power link between the whole mainland transmission network and the northern half of the Western Isles has been severed, although power continues to flow to the southern isles through a separate spur of undersea cable from Skye.

The fault in the subsea cable, which runs from Broadford substation, via Ardmore Point in Skye to the Isle of Harris, is thought to be about 15km from the Skye side of the Minch, although the exact location of the rupture has not yet been identified.

SSEN is today (Monday) carrying out undersea investigations to find the point of damage and establish whether, and how, a repair can be effected.

Meanwhile the Stornoway-based team at Battery Point are dealing with the logistics of keeping all the turbines in the diesel-fired power station running for a prolonged period.

Negotiations are under way with mainland power station teams, to bring manpower to the islands and keep the power station running for what may be months through the winter.

Power station managers are also meeting local representatives of Scottish Fuels to arrange for extra deliveries of diesel. These will keep both Battery Point and back-up turbines at Arnish powering the islands.

The spokesperson for SSEN said: “There is no real time-scale which we can attach to this situation, we can only say that it will be for the foreseeable future.

“At the moment Battery Point has plenty of capacity for the islands’ power needs, but as the clocks go back and weather gets colder, we will also need to use Arnish in a support role.

“Mainland staff will be coming over to help staff the power station 24/7 for the time that is needed, so that we can ensure our own teams get their rest days and off-duty time while this is happening.”

Power to all of the two islands was lost at 10.28am on Friday (16 October) and the power station was fired up and had all areas on supply by 12.50pm.

At the time of the power cut, local SSEN workers were put under further pressure by a public statement issued by Comhairle nan Eilean Siar, who described as ‘unacceptable’ the loss of power, which they mistakenly attributed to a planned outage.

They said: “Comhairle nan Eilean Siar will be making strong representations to SSEN regarding today’s loss of electricity supply. SSEN declared on their website that this was a “planned outage”. However, no notice was given to islanders. This is unacceptable.”

The planned outage notified on the SSEN page was, in fact, a piece of routine maintenance which affected just five addresses in Arivruach.

Last month, SSEN responded angrily to a decision by Ofgem that the substation at Broadford in Skye should not be funded for replacement, despite a needs case showing that the station and its supporting equipment was near the end of its life and ought to be replaced.

SSEN said in their consultation materials: “The current line was constructed in three distinct sections between 1956 and 1989 and is now reaching the end of its operational life. 

“Its planned replacement is essential to maintain security of supply to homes and businesses along its route, as well as to the Western Isles, which is supplied by two subsea cables from Ardmore point.”

Pictures show the power station at Battery Point running full steam ahead on Sunday and the route of the subsea cables (dotted lines) running between Skye and Harris (SSEN)