A method for suppressing an electric arc or corona discharge includes providing a device capable of storing, transmitting, or generating an electrical current or field; and enveloping at least a portion of said device with a dielectric gas consisting essentially of: sulfur hexafluoride; a second component selected from the group consisting of 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 combinations of two or more of these; and optionally, an additive selected from the group consisting of stabilizers, metal passivators, corrosion inhibitors, and lubricants.