A connector arrangement includes a universal terminal block having a body containing a chamber in which is removably mounted one of a plurality of function control modules as used in commercial, industrial and residential installations, wherein a pair of module contacts on the module are brought into electrical engagement with a pair of stationary contacts mounted in the chamber, thereby to connect the module to a pair of external insulated conductors via bus bars and terminals contained in the terminal block body. Various types of function control modules may be used with a single universal terminal block. The modules may include locking devices for locking the module to the universal terminal block. The terminal block includes mounting feet on the side thereof remote from the chamber, whereby selective modules may be substituted for one another when the terminal block is mounted on a support rail.