Current interrupting apparatus

Current interrupting apparatus comprising a housing having an open end, a thermostatic member mounted in the housing, the thermostatic member adapted for movement between first and second positions, movable and stationary contact means mounted within the housing, the movable contact operatively connected to the thermostatic member so that the contacts will be in engagement when the thermostatic member is in the first position and will be out of engagement when the thermostatic member is in the second position, electrical terminals electrically connected to the respective movable and stationary contact means, and an electrically insulative header closing the open end of the housing and maintaining the terminals electrically separated from one another and an atmosphere within the housing essentially consisting of a mixture of argon and helium in which the mixture consists of from 80-95 parts argon and 20-5 parts helium.