This is the fourth edition of CSA C22.2 No. 55, Special use switches. It supersedes the previous editions published in 1986, 1957, and 1942. It is one of a series of Standards issued under Part II of the Canadian Electrical Code. For general information on the Standards of the Canadian Electrical Code, Part II, see the Preface of the latest edition of CAN/CSA-C22.2 No. 0.