SHET’s Insulation and Interruption Gas Exceptional Event claim at Blackhillock (RIIO-ET3)
- Publication type:
- Consultation
- Publication date:
- Closing date:
- 20 November 2026
- Topic:
- Electricity transmission,
- Energy network price controls
- Subtopic:
- RIIO-T3: transmission price control 2026 to 2031
Minded-to position on Scottish Hydro Electric Transmission’s (SHET) Exceptional Event claim for Insulation and Interruption Gas leakage at its Blackhillock 400kV substation.
Consultation description
Special Condition (SpC) 4.3 Insulation And Interruption Gas emissions output delivery incentive (IIGIt) of the Electricity Transmission (ET) licence is designed to incentivise a reduction in the leakage of Insulation and Interruption Gases (IIGs) from assets on the ET network, and to support the transition to low greenhouse gas-alternative IIGs. ET licensees receive a reward for meeting or outperforming target IIG emissions, which is set in line with each licensee’s Science-Based Target for emissions reduction. Failure to meet this target results in a penalty.
Part C of SpC 4.3 includes an IIG Exceptional Event mechanism, which allows emissions to be excluded from the IIG incentive performance calculation following a licensee’s submission and Ofgem’s review of an IIG Exceptional Event claim.
SHET submitted an IIG Exceptional Event claim on 25 August 2026 for a leak that occurred on 12 August at its Blackhillock 400kV substation. Ofgem has assessed information provided by SHET in support of its claim and is consulting on our minded-to position to accept SHET’s claim.
Who should respond
- ET licensees
- Consumer groups
How to respond
Submit your response by 20 November 2026 by emailing RIIO3@ofgem.gov.uk.