Ofgem received a notification from SSEN Transmission on 1 November 2024 regarding a leakage event of 6.115kg of Sulphur Hexafluoride gas (SF6) at its Blackhillock substation, which occurred on 19 October 2024.
Companies are financially incentivised to reduce the leakage of Insulation and Interruption Gases (IIG), which are used in some transmission equipment. If an IIG leak occurs on a company's network due to an event that it believes was beyond its reasonable control then the company may make a case to the Authority to designate it an Exceptional Event for all or some of the quantity of IIG leaked during the event; and for it to be excluded from the calculation of the company's revenue reward or penalty.
It subsequently submitted a claim under Part C of Special Condition 4.3 that allows for Transmission Operators (TOs) to make a claim that a leakage event meets the definition of an IIG Exceptional Event.
We are consulting on our minded-to decision for SSEN’s Insulation and Interruption Gas Exceptional Event Claim.
Please respond with your views by 6 June 2025.