The course starts with an overview of low voltage circuit breakers and the fundamental requirements for the application of the circuit breakers in practice. It then follows with the different types of medium and high voltage circuit breakers, and the methods applied for effective arc extinction. The requirements for switchgear to be certified as Internal Arc Rated switchgear, are also addressed before finally looking at the role and application in coordination of protection systems, as well as the basic maintenance requirements of circuit breakers.