A modular electrical switch device including: a cut-off unit including unitary cut-off units; an actuating unit of the unitary cut-off units including an electromagnetic actuator including a fixed cylinder head and a movable reinforcement; a mechanism allowing the actuating unit to be fixed to the cut-off unit; a quick attachment mechanism allowing removable fixing of the actuating unit on the cut-off unit, and including at least one coupling hook configured to fix and hold the cut-off unit to the actuating unit, and to engage with an actuating device of the unitary cut-off unit to transmit movement of the actuator.