SF6-Free Gas-Insulated Switchgear: JST Dry Air GIS for Substations and Data Centers

Why owners are writing SF6-free into the spec

SF6 is an excellent insulator, which is why gas-insulated switchgear packs so many ways into a small tank. It is also a potent greenhouse gas: the EPA states that over 100 years SF6 is 23,500 times more effective at trapping heat than the same amount of CO2, with an atmospheric lifetime of more than 1,000 years. Every SF6 unit carries gas tracking, pressure monitoring and end-of-life recovery obligations.

Federal rules focus on reporting rather than bans, and the EPA's summary of state SF6 rules lists none for Texas or Oklahoma. The pressure comes from elsewhere: California's gas insulated equipment regulation phases out new SF6 equipment by voltage class between 2025 and 2033, New York's Part 495 starts a voltage-based phase-out in 2027, and Massachusetts caps leak rates. Owners with national fleets or corporate emissions targets, including many data center developers, increasingly specify SF6-free regardless of where the site is. Our guide Solid Dielectric vs SF6 Switchgear tracks the regulatory picture in detail (verified September 2026).

JST dry air GIS: the SF6-free option that keeps the GIS footprint

JST Power Equipment's dry air platform replaces SF6 with natural dry air while keeping the sealed-tank construction of gas-insulated switchgear. Ratings are from manufacturer data; confirm your configuration with a rep.

Model	Voltage	Current	Short-time withstand	BIL	Notes
J10N	5 kV	600 A	20 kA	75 kV	Compact 5 kV primary and secondary distribution lineups
J20N	38 kV (69 kV planned)	1200 A	31.5 kA	170 kV	Up to 75% less space than air-insulated gear; UL listed; IEC and IEEE internal arc classification; serviced from the front panel

By removing SF6, the J10N and J20N eliminate greenhouse-gas handling and reporting burdens and keep the unit outside rules written for SF6 gas-insulated equipment, while still cutting substation footprint compared with air-insulated switchgear.

Other SF6-free paths, and where SF6 still fits

Need	SF6-free option	Ratings on file
Indoor 5–15 kV lineups, no insulating gas at all	JST J100CLAD air-insulated metal-clad with J3MAG vacuum breakers	5–15 kV, up to 3000 A, 25–50 kA, 3-cycle
Padmount and underground distribution switching	G&W Trident solid dielectric family (epoxy-encapsulated vacuum)	15/25/35 kV classes, 630 A, 12.5 kA (Trident-S up to 16 kA); submersible
Automatic source transfer on campus loops	G&W Trident-SR	15–38 kV, 630 A, 12.5 kA, 10,000 mechanical operations
Ratings above today's dry air range	JST J20X C-GIS (SF6 + air)	38 kV 2500 A 31.5 kA or 69 kV 1200 A 31.5 kA; fully arc resistant

At 630 A and 12.5 kA, solid dielectric matches SF6 padmount gear. Above about 16 kA or at 900 A, or when you need integral cable grounding in the switch, SF6 families such as the G&W PNI, LPFI and GRAM are still the practical padmount choice; see the padmount switchgear line.

What to send

• Voltage class and BIL, continuous current and short-time or interrupting duty
• Bus arrangement: number of incoming and feeder ways, tie, metering and relaying needs
• Indoor or outdoor placement and available footprint
• Owner's SF6 policy or any state exposure (California, New York, Massachusetts)
• Project location, end user and required on-site dates

Switchgear lead times averaged 44 weeks in Wood Mackenzie's Q2 2025 survey (reported by POWER, January 2026). We confirm the current factory figure for your configuration rather than quoting a date here.

Frequently asked questions