Its official - 2018 Humber Gateway power loss due to cable handling fault

In: Cables
12/03/2020

Transmission Service Reduction in the Humber Gateway transmission system from 6 February 2018 to 22 March 2018 was caused by an exceptional event according to the UK regulator, Ofgem. Operated by Humber Gateway OFTO Limited, the system delivers electricity ashore for the Humber Gateway offshore wind farm.

Humber Gateway OFTO Limited confirmed that the export cable failed due to damage onshore, inside a duct made of polypropylene pipe. Deposits indicated that the fault had started in the cable and was not caused by damage outside of the duct. The investigation by the cable manufacturer found that ‘the fault is due to a relatively small diameter indentation made to the exterior of the cable’ and that the ‘damage must have occurred pre installation as it would not have been possible for something to perforate the HDD duct and remain undetected’.

Ofgem stated 'Given this, we accept that the Licensee could not reasonably have been expected to identify the fault during the due diligence process prior to asset transfer, and that the root cause of the event was beyond the reasonable control of the Licensee. We therefore consider that the claim constitutes an Exceptional Event.'

Ofgem went on to point out that two significant delays occurred during the repair. 12 days were lost in total. It took the OFTO four working days to conclude that not all of the switchgear earths had been disconnected, after which they contacted the manufacturer for advice. It then took a further ten days before the manufacturer agreed to visit the site to investigate the earthing issue.


Humber Gateway is located in the UK North Sea, approximately 8km off the coast of the East Yorkshire. The project consists of 73 MHI Vestas V112-3.0MW turbines and has a maximum output of 219MW.

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