Sulphur hexafluoride or SF6 is a gas used for breaking and insulation. Schneider Electric has been using an average of 400 grams of SF6 per product since 1973 in its medium-voltage devices such as circuit breakers and switches. SF6 has the following advantages:
- excellent gas for quenching the electrical arc that occurs when contacts open at medium voltage;
- very good insulator: SF6 is twice as effective as air, which makes it possible to reduce the size of devices;
- colorless, inert, non-toxic, non-flammable. It poses no danger to employees;
- it does not contribute to the destruction of the ozone layer.
However, if SF6 gas is not recovered at end of life, it may escape into the atmosphere and contribute to climate warming: its contribution to the greenhouse effect is 24,000 times more powerful than CO2.