A system, comprising: a first group of two or more automatic transfer switch cassettes, each cassette of the first group of cassettes comprising: a first stationary bar; a first plurality of fixed contact members (102, 104); and a first plurality of movable contact members (108, 110), each of the first plurality of movable contact members electrically coupled and rotatably connected to the first stationary bar and configured to contact one of the first plurality of fixed contact members (102, 104); a second group of two or more automatic transfer switch cassettes, each cassette of the second group of cassettes comprising: a second stationary bar; a second plurality of fixed contact members (102, 104); and a second plurality of movable contact members (108, 110), each of the second plurality of movable contact members electrically coupled and rotatably connected to the second stationary bar and configured to contact one of the second plurality of fixed contact members (102, 104); at least one operating mechanism configured to control opening and closing of the first plurality of movable contact members (108, 110) and the second plurality of movable contact members (108, 110); and, for each cassette of the first group of cassettes, a connector configured to connect the first stationary bar of the cassette of the first group of cassettes to the second stationary bar of a cassette of the second group of cassettes, wherein the first stationary bar of a first cassette of the first group of two or more cassettes is connected to the second stationary bar of a first cassette of the second group of two or more cassettes, and the first stationary bar of a second cassette of the first group of two or more cassettes is connected to the second stationary bar of a second cassette of the second group of two or more cassettes. a first group of two or more automatic transfer switch cassettes, each cassette of the first group of cassettes comprising: a first stationary bar; a first plurality of fixed contact members (102, 104); and a first plurality of movable contact members (108, 110), each of the first plurality of movable contact members electrically coupled and rotatably connected to the first stationary bar and configured to contact one of the first plurality of fixed contact members (102, 104); a first stationary bar; a first plurality of fixed contact members (102, 104); and a first plurality of movable contact members (108, 110), each of the first plurality of movable contact members electrically coupled and rotatably connected to the first stationary bar and configured to contact one of the first plurality of fixed contact members (102, 104); a second group of two or more automatic transfer switch cassettes, each cassette of the second group of cassettes comprising: a second stationary bar; a second plurality of fixed contact members (102, 104); and a second plurality of movable contact members (108, 110), each of the second plurality of movable contact members electrically coupled and rotatably connected to the second stationary bar and configured to contact one of the second plurality of fixed contact members (102, 104); a second stationary bar; a second plurality of fixed contact members (102, 104); and a second plurality of movable contact members (108, 110), each of the second plurality of movable contact members electrically coupled and rotatably connected to the second stationary bar and configured to contact one of the second plurality of fixed contact members (102, 104); at least one operating mechanism configured to control opening and closing of the first plurality of movable contact members (108, 110) and the second plurality of movable contact members (108, 110); and, for each cassette of the first group of cassettes, a connector configured to connect the first stationary bar of the cassette of the first group of cassettes to the second stationary bar of a cassette of the second group of cassettes, wherein the first stationary bar of a first cassette of the first group of two or more cassettes is connected to the second stationary bar of a first cassette of the second group of two or more cassettes, and the first stationary bar of a second cassette of the first group of two or more cassettes is connected to the second stationary bar of a second cassette of the second group of two or more cassettes.