The invention relates to a flush mount junction and terminal box of variable plan configuration, with a first internal cover (5), tightly fitted to the opening of the junction box holder with screws (6), connected to a decorative second external cover (7) by detachable and hidden joining means, preferably magnets (9), that are associated with ferric parts (10) located on the internal surface (7B) of the second external cover (7), the first internal cover (5) being sunken and the second external cover (7) being flush with the surface of the wall (3). The box comprises a peripheral frame forming therewith a single compact and inseparable unit and said box also being suitable for including one or more lighting LEDs (11), located on the outer face of the first internal cover (5) or in the channel (21) located between the vertical wall (13A) of the peripheral frame (13) and the junction box (1).