A group of electrical accessories for fitting in a wall, the group comprising: • two distinct modules (100, 200) each including: • a base (110, 210) that is closed at the front by a front wall (111, 211); and • at least two sets of electrical contacts (120A, 120D, 220A, 220D) accessible through the base (110, 210) via two respective sets of insertion openings (115A, 115D, 215A, 215D), each of which distributed on either side of a mean direction (D1A, D1D, D2A, D2D) parallel to said front wall (111, 211); a first one of the bases being fitted with fastener means for fastening in an electrical box; and a second one of the bases being fitted with fastener means for fastening in a cavity formed in the wall; • a connection bar including electrical conductors (316, 317, 318) that are adapted to connect the electrical contacts of a set of electrical contacts (120A, 120D) of one of the modules with the electrical contacts of a set of electrical contacts (220A, 220D) of the other module; the group being characterized in that said two mean directions (D1A, D1D, D2A, D2D) are mutually orthogonal, and in that the fastener means of the second base include a shoulder that is adapted to bear against the front face of the wall, and retractable catch means that are adapted to catch on the rear face of the wall. • two distinct modules (100, 200) each including: • a base (110, 210) that is closed at the front by a front wall (111, 211); and • at least two sets of electrical contacts (120A, 120D, 220A, 220D) accessible through the base (110, 210) via two respective sets of insertion openings (115A, 115D, 215A, 215D), each of which distributed on either side of a mean direction (D1A, D1D, D2A, D2D) parallel to said front wall (111, 211); a first one of the bases being fitted with fastener means for fastening in an electrical box; and a second one of the bases being fitted with fastener means for fastening in a cavity formed in the wall; • a connection bar including electrical conductors (316, 317, 318) that are adapted to connect the electrical contacts of a set of electrical contacts (120A, 120D) of one of the modules with the electrical contacts of a set of electrical contacts (220A, 220D) of the other module; • a base (110, 210) that is closed at the front by a front wall (111, 211); and • at least two sets of electrical contacts (120A, 120D, 220A, 220D) accessible through the base (110, 210) via two respective sets of insertion openings (115A, 115D, 215A, 215D), each of which distributed on either side of a mean direction (D1A, D1D, D2A, D2D) parallel to said front wall (111, 211); a first one of the bases being fitted with fastener means for fastening in an electrical box; and a second one of the bases being fitted with fastener means for fastening in a cavity formed in the wall; a first one of the bases being fitted with fastener means for fastening in an electrical box; and a second one of the bases being fitted with fastener means for fastening in a cavity formed in the wall; • a connection bar including electrical conductors (316, 317, 318) that are adapted to connect the electrical contacts of a set of electrical contacts (120A, 120D) of one of the modules with the electrical contacts of a set of electrical contacts (220A, 220D) of the other module;