A corner box assembly for housing electrical components for distribution of power and mounting at a surface where a wall meets a floor of a room for housing electrical sockets, switches and cables, said corner box assembly comprising: - at least two end parts comprising a first end part and a second end part, said first end part being of matching profile with said second end part to removably attach with each other and thereby form said corner box; - one or more mid parts configured to be assembled in-between said end parts, said mid parts are adapted to attach with said end parts thereby increasing the length of the corner box assembly; and - mid walls acting as separator between different modules of said electrical components, configured to be attached onto said mid parts for reinforcing said corner box assembly; wherein said mid parts are provided with at least two engaging edges (116-1, 116-2) for engaging with an adjoining end part or mid part, wherein said end parts are each provided with one engaging edge (116-1, 116-2) for engaging with an adjoining end part or a mid part, wherein said end parts and mid parts are configured to engage with adjoining mid parts or end parts by means of at least one locking arrangement, wherein said locking arrangement comprises linear fixing snaps for rigid fixation, protruding in an outwardly manner from top and bottom parts of said engaging edges (116-1, 116-2) of the mid parts and end parts; and adjustable fixing snaps for relative alignment of the end and mid parts (102, 104), protruding in an outwardly manner from said engaging edges (116-1, 116-2), wherein said engaging edges (116-1, 116-2) of said mid parts further comprise receiving slots to engage with said linear fixing snaps and with said adjustable fixing snaps for engaging with an adjoining end part or mid part, wherein said engaging edge (116-1, 116-2) of the second end part and engaging edge (116-1, 116-2) of the first end part further comprise receiving slots to engage with said linear fixing snaps and with said adjustable fixing snaps for engaging with an adjoining end part or mid part, wherein said mid parts are provided with grooved mounting means at an inner walls configured to form a lap joint with said mid walls, and wherein said mid parts and end parts are provided with knock outs acting as provision for inserting cables and conduits. - at least two end parts comprising a first end part and a second end part, said first end part being of matching profile with said second end part to removably attach with each other and thereby form said corner box; - one or more mid parts configured to be assembled in-between said end parts, said mid parts are adapted to attach with said end parts thereby increasing the length of the corner box assembly; and - mid walls acting as separator between different modules of said electrical components, configured to be attached onto said mid parts for reinforcing said corner box assembly; wherein said mid parts are provided with at least two engaging edges (116-1, 116-2) for engaging with an adjoining end part or mid part, wherein said end parts are each provided with one engaging edge (116-1, 116-2) for engaging with an adjoining end part or a mid part, wherein said end parts and mid parts are configured to engage with adjoining mid parts or end parts by means of at least one locking arrangement, wherein said locking arrangement comprises linear fixing snaps for rigid fixation, protruding in an outwardly manner from top and bottom parts of said engaging edges (116-1, 116-2) of the mid parts and end parts; and adjustable fixing snaps for relative alignment of the end and mid parts (102, 104), protruding in an outwardly manner from said engaging edges (116-1, 116-2), wherein said engaging edges (116-1, 116-2) of said mid parts further comprise receiving slots to engage with said linear fixing snaps and with said adjustable fixing snaps for engaging with an adjoining end part or mid part, wherein said engaging edge (116-1, 116-2) of the second end part and engaging edge (116-1, 116-2) of the first end part further comprise receiving slots to engage with said linear fixing snaps and with said adjustable fixing snaps for engaging with an adjoining end part or mid part, wherein said mid parts are provided with grooved mounting means at an inner walls configured to form a lap joint with said mid walls, and wherein said mid parts and end parts are provided with knock outs acting as provision for inserting cables and conduits.