A modular electrical switch device, comprising: at least one electric switch module comprising an enclosure having two opposite side panels, a rotatable blade contact being supported within the enclosure on a roll, the roll being rotatably supported by its ends in openings in the side panels of the enclosure, an actuator module comprising a frame with a first side wall, a second opposite side wall, a front wall, and an opposite rear wall, the second side wall seating against a side panel of the enclosure of the electric switch module, the actuator module further comprising actuators and a power transmission apparatus being connected to the roll in order to operate the rotatable blade contact, a power module seating against the first side wall of the actuator module, the power module comprising power supply means for supplying power to the actuators of the actuator module, a control module seating against the front wall of the actuator module, the control module comprising control means for controlling the power module, and data transfer means, complementary electric connectors (121, 122, 221, 222) providing an electrical connection between the power module and the actuator module, further complementary electric connectors (143, 343) providing an electric connection between the control module and the actuator module, and still further complementary electrical connectors (231, 331) providing an electrical connection between the control module and the power module, complementary mechanical guiding means (111, 112, 211, 212) providing a mechanical connection between the power module and the actuator module and screws providing a mechanical connection between the control module and the actuator module, wherein the power module and the control module are both separately replaceable in the modular electrical switch device. at least one electric switch module comprising an enclosure having two opposite side panels, a rotatable blade contact being supported within the enclosure on a roll, the roll being rotatably supported by its ends in openings in the side panels of the enclosure, an actuator module comprising a frame with a first side wall, a second opposite side wall, a front wall, and an opposite rear wall, the second side wall seating against a side panel of the enclosure of the electric switch module, the actuator module further comprising actuators and a power transmission apparatus being connected to the roll in order to operate the rotatable blade contact, a power module seating against the first side wall of the actuator module, the power module comprising power supply means for supplying power to the actuators of the actuator module, a control module seating against the front wall of the actuator module, the control module comprising control means for controlling the power module, and data transfer means, complementary electric connectors (121, 122, 221, 222) providing an electrical connection between the power module and the actuator module, further complementary electric connectors (143, 343) providing an electric connection between the control module and the actuator module, and still further complementary electrical connectors (231, 331) providing an electrical connection between the control module and the power module, complementary mechanical guiding means (111, 112, 211, 212) providing a mechanical connection between the power module and the actuator module and screws providing a mechanical connection between the control module and the actuator module, wherein the power module and the control module are both separately replaceable in the modular electrical switch device.