Circuit breakers intended for service on AC circuits above 1,500 Volts are classified as power circuit breakers. Metal-clad switchgear with air breakers or load interrupter switches are most often used for outdoor service up to 35 kV and up to 1,000 MVA interrupting duty. Their advantages include freedom from oil-fire hazard, compactness, appearance, ease of maintenance and flexibility. The metal-clad switchgear is usually throat-connected to the main power transformers, although roof entrance bushings are sometimes also used.
