Scottish and Southern Electricity Networks (SSEN) are investigating whether an unknown third party caused damage to a subsea cable, knocking out power to the whole of Lewis and Harris on Friday (16 October).

And it’s possible that the 32km cable from Ardmore in Skye to Beacravik in the Bays of Harris may need to be completely replaced to restore transmission.

A statement issued late yesterday (Monday 19 October) confirmed that a fault has been identified on the 33,000-volt subsea electricity distribution cable, with initial location testing indicating a fault around 15km from shore and in an area of deep water.

The cable’s entire length had been inspected by SSEN Distribution this summer, with no indication of any risk to its integrity, according to SSEN.

Friday’s fault caused a total power loss to Lewis and Harris and the islands have been supplied by locally generated power from Battery Point’s diesel-fired turbines since lunchtime that day, as reported on welovestornoway.com yesterday (https://www.welovestornoway.com/index.php/articles-auto-3/18328-power-break-in-subsea-cable)

A spokesperson for SSEN said: “SSEN is committed to restoring the network to full operation as soon as is practicably possible. Further investigations are underway to identify the root cause of the fault, including to understand any instance of third-party damage, and to implement a restoration plan.

“This will establish whether a repair can be undertaken or, given the fault location, an end-to-end cable replacement is required.

“There is no impact to the supply of electricity to homes and businesses on Lewis and Harris as a result of the fault. In line with established network operation procedures, Battery Point Power Station will remain in full operation for the duration of the fault alongside on-island renewable generation.

“Further contingency measures, including coordination of additional fuel deliveries to the power station, are in place to ensure a continued safe and secure supply of electricity.”

An additional implication of the break to Lewis and Harris’s only mainland connection is that power exported by island wind turbines to the national grid will be interrupted. This could have significant consequences for community trusts using income from windpower generation.

The spokesperson for SSEN said: “As a result of the fault, there will be some restrictions to electricity generation export during the period. SSEN is in close contact with generators on Lewis and Harris to manage any generation constraint required and will look to minimise disruption wherever possible.

“A further update will be provided once investigations are fully complete and a restoration plan is in place.”