An assembly comprising: • a connector (1; 600; 700; 800) for flush mounting in a wall , said connector comprising: • a base that defines an inlet opening (11; 60) for at least one electrical conductor , and that presents a front edge; and • at least two distinct arms that extend from the base , mainly at the front of the front edge of the base , and having free ends that present catch means for catching on the wall , and • an electrical box (200; 260) for receiving an electrical accessory and including means for its attachment to the wall and a side wall (210; 261) that externally presents at least two grooves (214, 216; 268) for passing the arms (14, 16; 614, 616) of the connector (1; 600; 700; 800), and that is closed at the rear by a rear wall , the assembly being characterized in that it includes at least one connection element that is fastened to the base and that includes an inlet terminal for connecting said electrical conductor , and an outlet terminal that is accessible via the front of the base for connecting at least one electrical accessory, and in that the rear wall of the electrical box (200; 260) presents at least one access opening for accessing the outlet terminals of the connection elements of the connector · • a connector (1; 600; 700; 800) for flush mounting in a wall , said connector comprising: • a base that defines an inlet opening (11; 60) for at least one electrical conductor , and that presents a front edge; and • at least two distinct arms that extend from the base , mainly at the front of the front edge of the base , and having free ends that present catch means for catching on the wall , and • a base that defines an inlet opening (11; 60) for at least one electrical conductor , and that presents a front edge; and • at least two distinct arms that extend from the base , mainly at the front of the front edge of the base , and having free ends that present catch means for catching on the wall , and • an electrical box (200; 260) for receiving an electrical accessory and including means for its attachment to the wall and a side wall (210; 261) that externally presents at least two grooves (214, 216; 268) for passing the arms (14, 16; 614, 616) of the connector (1; 600; 700; 800), and that is closed at the rear by a rear wall , the assembly being characterized in that it includes at least one connection element that is fastened to the base and that includes an inlet terminal for connecting said electrical conductor , and an outlet terminal that is accessible via the front of the base for connecting at least one electrical accessory, and in that the rear wall of the electrical box (200; 260) presents at least one access opening for accessing the outlet terminals of the connection elements of the connector · the assembly being characterized in that it includes at least one connection element that is fastened to the base and that includes an inlet terminal for connecting said electrical conductor , and an outlet terminal that is accessible via the front of the base for connecting at least one electrical accessory, and in that the rear wall of the electrical box (200; 260) presents at least one access opening for accessing the outlet terminals of the connection elements of the connector · <EOS>