The present patent discusses a r constructive device introduced in box hinge, this box being meant to receive the assembly of electrical equipments and/or components. Current prior art comprises a patent document (ES 1 046 460) that describes a box of the type meant to serve as a place for the assembly of electrical equipments and/or components, being essentially formed by a main body and its respective cover, this cover being connected to the body by means of a type of hinge that allows opening the cover by tilting. Although this is a practical solution, the type of hinge used in the abovementioned document does not allow full tilting of the cover in relation to the body of the box, i.e., this tilting is not total. Therefore, one of the objectives of this Utility Model patent is to provide a special type of hinge that allows full tilting of the cover in relation to the body of the box, this tilting allowing opening the cover by 180°. This degree of opening provides easy access to any electrical equipment and/or device assembled inside the box, as well as allowing the cover to be totally hanging in relation to the main body at a more favorable condition. In view of the abovementioned prior art and considering the objectives proposed, the present Utility Model patent was developed, which will be described in detail with reference to the drawings listed below, where: Figure 1 shows a perspective view of the box incorporating the present hinge; the box is completely open; Figure IA shows a magnified detail from the figure, as indicated by arrow A; Figure 2 shows another perspective view of said box, this view being taken from another angle of observation; Figure 2A shows a detail from figure 2, as indicated by arrow B. In accordance with what is shown by the above figures, the hinge discussed herein, which is generally indicated by the reference number 1, comprises a joint 2 having two pin-shaped projections 3, one at each of its two ends. The joint 2 has a "U" shape, which is determined so as to allow full opening between the cover 4 and the main body 5 that make up the box 6. The hinge discussed herein, apart from the joint 2, which is an independent part, also has constructive details both on the cover 4 and on the main body 5. The abovementioned constructive details are sectors of walls 7 designed in such a way as to form a structure for fitting the joint 2 to the main body 5, a general view being given in figures 1 and 2 and a more detailed view in figures IA and 2A. Each of the walls has a cutout 8 with an opening 9 and a slot 10 for the pin-shaped projections 3. There are also other walls 7A on the cover 4, with configuration similar to that of the walls 7 of the main body 5. The hinge discussed herein has a structure substantially simpler than that of the example from prior art and, contrary to said example, allows the cover 4 to be opened at an angle close to 180° in relation to the main body 5, as can easily be seen in the figures illustrating this Utility Model patent.