A modular system for producing an electrical device includes: a plurality of terminal devices arrangeable on a printed circuit board to connect electrical conductors to the printed circuit board, the terminal devices each having a housing that has a connection side, arranged on which is a plug-in connection opening for insertion of an electrical conductor, and two lateral flanks, which are spaced apart from each other along a width direction and between which the connection side extends. A first terminal device of the plurality of terminal devices is a spring-force terminal. A second terminal device of the plurality of terminal devices is a screw-connection terminal. A housing of the first terminal device and a housing of the second terminal device have a same width, measured along the width direction.