NOVELTY - Suppressing an electric arc or corona discharge comprises: (a) providing a device capable of storing, transmitting, or generating an electrical current or field; and (b) enveloping at least a portion of the device with a dielectric gas consisting substantially sulfur hexafluoride, a second component, and optionally an additive comprising stabilizers, metal passivators, corrosion inhibitors, and lubricants.    USE - The method is useful for: suppressing an electric arc or corona discharge; and forming an azeotrope-like composition.    ADVANTAGE - The azeotrope-like composition exhibits good chemical stability, low global warming potential, non-flammability and dielectric performance. The dielectric gas is highly resistant to the flow of electrical current, thus serves as an electrical insulator.    DETAILED DESCRIPTION - Suppressing an electric arc or corona discharge comprises: (a) providing a device capable of storing, transmitting, or generating an electrical current or field; and (b) enveloping at least a portion of the device with a dielectric gas consisting substantially sulfur hexafluoride, a second component comprising nitrous oxide, carbon dioxide, trifluoromethane (R32), trifluoroiodomethane, octafluoropropane (R218), 1,1,1,2,2-pentafluoroethane (R125), propane (R290), 1,1,1,2-tetrafluoropropene (HFO-1234yf), 1,2,3,3-tetrafluoro-2-propene (HFO-1234yc), 1,1,3, 3-tetrafluoro-2-propene (HFO-1234zc), 1,1,1,3-tetrafluoro-2-propene (HFO-1234ze), 1,1,2,3-tetrafluoro-2-propene (HFO-1234ye), 1,1,1,2,3-pentafluoropropene (HFO-1225ye), 1,1,2,3,3-pentafluoropropene (HFO-1225yc), 1,1,1,3,3-pentafluoropropene (HFO-1225zc), (Z) 1,1,1,3-tetrafluoropropene (HFO-1234zeZ), (Z) 1,1,2,3-tetrafluoro-2-propene (HFO-1234yeZ), (E) 1,1,1,3-tetrafluoropropene (HFO-1234zeE), (E) 1,1,2,3-tetrafluoro-2-propene (HFO-1234yeE), (Z) 1,1,1,2,3-pentafluoropropene (HFO-1225yeZ), (E) 1,1,1,2,3-pentafluoropropene (HFO-1225yeE) and two or more of their mixtures, and optionally, an additive comprises stabilizers, metal passivators, corrosion inhibitors and lubricants. INDEPENDENT CLAIMS are included for:    (1) a gas insulated electrical device comprising: (a), and a dielectric gas consisting substantially sulfur hexafluoride and the second component, where at least a portion of the one or more components is enveloped by the dielectric gas;    (2) a method for flame suppression comprising: providing a contained environment having, or adapted to receive, one or more flammable materials; and introducing into the environment a fluid composition consisting substantially sulfur hexafluoride and the second component and optionally the additive, where the gaseous mixture is present in an amount to reduce the flammability of the environment; and    (3) a rigid closed cell foam comprising the dielectric gas consisting substantially sulfur hexafluoride, and the second component, where the dielectric gas is disposed within cells of the foam.