Sulphur hexafluoride (SF₆) is one of the most potent greenhouse gases in use today, with a global warming potential approximately 24,300 times greater than carbon dioxide (CO₂) over a 100-year period. Despite being used in relatively small quantities, its environmental impact is significant. It is one of the 6 notified greenhouse gases in the F Gas regulations.
Across Great Britain, electrical switchgear is estimated to contain around 1 million kg of SF₆, spread across more than 200,000 units. Approximately 97% of these assets operate at distribution level, within medium and high voltage networks. For decades, SF₆ has delivered compact, reliable switchgear.
Why SF₆ Became the Standard
SF₆ offers unrivalled electrical insulation and arc‑quenching performance, allowing high-energy switching to take place safely within compact enclosures. Since the 1970s, this has enabled compact, lower‑maintenance switchgear, replacing older compressed‑air and oil‑filled designs.
However, as equipment ages, seals degrade and gas leakage becomes inevitable. Even small losses are environmentally significant due to SF₆’s extreme global warming potential and long atmospheric lifetime.
Regulation Driving Change
SF₆ has been targeted by international agreements such as the Kyoto Protocol and, more recently, the EU F‑Gas Regulation[1], which sets out a phased withdrawal of SF₆-containing electrical equipment. Key milestones include:
- January 2026 – No installation of SF₆ switchgear up to and including 24 kV
- January 2028 – No installation from 52 kV up to and including 145 kV
- January 2030 – No installation above 24 kV up to and including 52 kV
- January 2032 – No installation above 145 kV
- January 2035 – Prohibition on the use of SF₆ for maintenance and servicing
Although these dates currently apply to the EU, it is widely expected that the UK will align closely as end users use SF₆ free switchgear as one of the criteria for net zero ambitions. For an industry that has relied on SF₆ technology for over 50 years, this represents a fundamental change.
SF₆ Free Alternatives
All European switchgear manufacturers have SF6 free strategies to meet the challenges of the European ban in early 2025, Schneider Electric hosted members of West Yorkshire IET at its Leeds Smart Factory and Innovation Hub, demonstrating Ringmaster AirSeT — a new SF₆‑free ring main unit rated up to 12kV. [2]
Using pure air for insulation combined with vacuum for interruption, the AirSeT offers equivalent performance to conventional SF₆ units while retaining an a similar or identical footprint — a critical factor for distribution networks with space constraints and unit substation designs.
As regulatory deadlines approach, SF₆‑free technologies are expected to become standard across Europe, with the UK close behind.
Considerations for the UK Network
The transition away from SF₆ presents several challenges including:
- Asset replacement strategy and timing
- Training and competence for new technologies
- Management and decommissioning of legacy SF₆ assets
Closing Thoughts
The removal of SF₆ from British switchgear marks a pivotal moment for the electricity industry. While driven by environmental necessity, it also presents an opportunity to modernise long‑established approaches to network design and operation.
[1] https://eur-lex.europa.eu/eli/reg/2024/573/oj