What Is SF6-Free Switchgear?

Gas-insulated switchgear (GIS) places energized conductors inside a sealed enclosure. Gas insulates live parts from grounded metal while allowing a compact arrangement. SF6 has long been used for this job, and some designs also used it to interrupt current. It is a potent greenhouse gas, so leaks and end-of-life handling matter. Restrictions on new fluorinated-gas equipment in some jurisdictions are driving interest in alternatives.

SF6-free does not say whether gear is air-insulated or gas-insulated, how an internal arc is managed, or whether a lineup fits a project. Start with the medium-voltage switchgear requirements, then check the insulating medium.

A circuit breaker has to stop current when its contacts open. In a vacuum interrupter, those contacts part inside a sealed vacuum bottle. The rest of the energized assembly still needs insulation from adjacent phases and the enclosure. In GIS, a gas can do that second job without being the arc-quenching medium inside the breaker.

This distinction prevents a common procurement mistake: a vacuum breaker does not, by itself, prove that a switchgear lineup contains no SF6. Some SF6-insulated GIS families use vacuum breakers. Conversely, SF6-free gear can use vacuum interruption with a different insulating gas, or an air-insulated construction. Ask for both the interruption medium and the insulation medium in the equipment submittal. Confirm how the enclosure is sealed, how gas condition is monitored, and what service work is required.

One SF6-free GIS approach uses gases derived from natural air, principally nitrogen and oxygen, to insulate the primary conductors. Manufacturers may describe such a mixture as Clean Air. This is a gas-insulation choice, separate from the vacuum interrupter that clears a fault. Environmental statements need the same boundary: a claim about the insulating gas is not automatically a claim about every material in the whole switchgear assembly.

Siemens NXPLUS C 24 blue is one example. Its Clean Air insulates conductors and its vacuum interrupters break current. Siemens states that the insulating gas has no fluorinated or PFAS gases and a global-warming potential below one. Those statements describe the gas; a buyer still needs to confirm the ordered lineup, ratings, listing, and installation arrangement. Other SF6-free designs use different insulation approaches, so compare the submitted configuration rather than treating the phrase as a common technical standard.

The voltage on a one-line drawing is the nominal system voltage. Switchgear carries a higher rated maximum equipment voltage and an associated impulse-withstand rating. A 13.8 kV system, for example, is normally specified with 15 kV class equipment; a 34.5 kV system calls for 38 kV class equipment. The voltage-class guide explains the mapping. Do not assume that a 24 kV-rated SF6-free model is suitable for a 34.5 kV system.

For a useful quotation, state nominal voltage, grounding, fault current, continuous bus and feeder current, cable arrangement, indoor or outdoor location, and the required standard or listing. Ask for the exact gas-insulation and breaker-interruption design. Internal-arc classification also needs care: IEC 62271-200 IAC designations and IEEE C37.20.7 accessibility types are different test frameworks, and one label does not establish the other. The arc-resistant switchgear guide covers the IEEE terms and the exhaust-path decision.

EU Regulation 2024/573 Article 13(9) prohibits putting into operation fluorinated-gas switchgear for primary or secondary distribution rated up to 24 kV from January 1, 2026, and above 24 kV through 52 kV from January 1, 2030, subject to derogations. This is a rule about EU commissioning, not a blanket rule on US sales.

California §95352 phases out acquisition of SF6 gas-insulated equipment: aboveground equipment below 38 kV from January 1, 2025; aboveground equipment at 38 kV from January 1, 2028; and belowground equipment at or below 38 kV with at least 25 kA from January 1, 2031. Exemptions apply. The acquisition date, installation type, voltage, and interrupting rating all matter.

EPA Part 98 Subpart DD is an emissions-reporting rule for qualifying electric power systems, not a federal ban on buying SF6 switchgear. It does not automatically cover every private facility. A buyer should identify the jurisdiction and regulated entity before turning any of these dates into a procurement requirement.

Compare electrical duty first: rated voltage and impulse withstand, continuous and short-circuit ratings, breaker type, internal-arc test, and service access. Then compare insulation, sealing, monitoring, maintenance, and end-of-life handling. A different footprint, cable termination, or arc exhaust route may require a room or protection-study revision.

Write SF6-free alongside the complete switchgear duty and relevant jurisdiction. It does not replace a one-line diagram, fault study, or submittal for the specific lineup.