WO2006094592A1

WO2006094592A1 - Junction box and/or switch and outlet box for electrical systems

Info

Publication number: WO2006094592A1
Application number: PCT/EP2006/001130
Authority: WO
Inventors: Piero Camillo Gusi
Original assignee: Vimar S.P.A.
Priority date: 2005-03-08
Filing date: 2006-02-09
Publication date: 2006-09-14
Also published as: EP1856781A1; CN101128966A; ITMI20050076U1

Abstract

A junction and/or switch and outlet box, particularly suitable to be flush-mounted in panels intended to form dry walls. The box (1) comprises: a substantially flat bottom wall (2), a side wall (3) that rises from the peripheral edge of the bottom wall (2), and at least one knock-out wall section (10, 20), formed in the side wall (3) and/or in the bottom wall (2), suitable to be removed so as to give rise to an aperture or window for insertion of the end of a corrugated protective conduit (40) inside which the electric cables carrying the electrical supply are passed. The box further comprises a retaining tongue (30) disposed opposite a substantially curved profile (11, 21) of the opening formed by removal of the wall section (10, 20). In this manner the corrugated conduit (40) can be retained between the retaining tongue (30) and the curved profile (11, 21).

Description

JUNCTION BOX AND/OR SWITCH AND OULTET BOX FOR ELECTICAL

SYSTEMS

DESCRIPTION

The present invention refers to a junction box and/or switch and outlet box for electrical systems, particularly suitable to be flush-mounted in panels intended to form light walls.

Household electrical systems are currently made by connecting together connection or junction boxes by means of corrugated protective conduits, generally of plastic material. Electrical cables connected to the electrical mains are passed inside the protective conduits, to convey the electrical power that must supply the user devices such as lights, sockets, machines, etc., which are situated in various parts of the building.

These boxes can serve as a simple connection for the electrical cables or they can be destined to hold sockets and switches or electrical modules of various types, such as switches, electrical sockets, sensors and the like. Thus even if reference will be made herein to junction boxes, the invention also extends to switch and outlet boxes.

Junction boxes are flush-mounted in masonry walls or also in prefabricated panels for the formation of dry walls.

In the case of masonry walls, the installer forms recessed seats in the wall in which the junction boxes are disposed. The ends of the protective conduits are inserted in the holes formed in the junction boxes and are made to protrude inside the box for about 10-15 cm. Subsequently the part of the conduit outside the box is fixed to the box with mortar. Lastly the end part of the conduit which protrudes inside the box is trimmed to allow installation in the box of supports and electrical modules.

In the building industry, for reasons of practicality and ease of cabling of electrical and plumbing systems, wide use is made of dry walls obtained by means of pre-fabricated panels, such as for example plasterboard, wood and plastic laminate panels and the like. These panels are disposed parallel and opposite each other so as to define a void for passage of the conduits. In this case, the junction boxes are fixed directly on said movable panels and are subsequently connected to each other with corrugated conduits. In the specific case of plasterboard walls with fittings a framework is installed whereon the panels are fixed, with precedence for the panels with junction boxes which will have to be cabled for electrical-type systems. To allow cabling, the rear access to the junction boxes is left free and will subsequently be closed with another panel.

The electrical system is formed by fixing the switch and outlet or junction boxes, by making shaped holes on the panels. Once the boxes have been inserted in the shaped holes and fixed to the panel, connections are made between the boxes with corrugated protective conduits.

These junction boxes are prepared with apertures for access of the end of the conduits, but do not ensure that the conduit is retained. Clips, wire or insulating tape are currently used to fix the conduits to the boxes. This is to prevent the conduit from slipping into the void formed between the two panels once the wall is composed, making its recovery impossible or very difficult.

As described above, junction boxes according to the prior art, besides leading to a considerable waste of time for installation, imply considerable uncertainty about the cabling inside the wall, especially in the case of dry walls formed of panels which give rise to voids into which the corrugated conduits can slip.

The object of the present invention is to overcome the drawbacks of the prior art by providing a junction box that is versatile, simple to install and at the same time able to ensure a good level of safety of execution of the electrical system.

This object is achieved, in accordance with the invention, with the characteristics listed in appended independent claim 1.

Advantageous embodiments of the invention are apparent from the dependent claims.

The junction and/or switch and outlet box for electrical systems according to the invention comprises:

- a substantially flat bottom wall, - a side wall which rises from the peripheral edge of the bottom wall, and

- at least one knock-out wall section, formed in the side wall and/or in the bottom wall, designed to be removed so as to give rise to an aperture or window for insertion of the end of a protective corrugated conduit wherein the electrical cables carrying the electrical current are passed.

The box further comprises a retaining tongue opposite a substantially curved profile of the aperture formed by removal of the wall section. In this manner the corrugated conduit can be retained and blocked in position between the retaining tongue and the curved profile of the aperture formed in the side wall or in the bottom wall.

Said box proves to be particularly suitable for flush-mounting in panels intended to form light walls. In fact the blocking system of the abovementioned corrugated conduit prevents said conduit from falling into the void formed between the two panels of a light wall.

Further characteristics of the invention will be made clearer by the detailed description that follows, referring to a purely exemplifying and therefore non limiting embodiment thereof, illustrated in the appended drawings, in which:

Figure 1 is a perspective view of a junction box according to the invention; Figure 2 is a perspective view of the box of Figure 1 turned upside down;

Figure 3 is an enlarged cross sectional view, illustrating a portion of the box of Figure 1 and a corrugated protective conduit exploded; and

Figure 4 is a sectional view like Figure 3, wherein the corrugated protective conduit has been blocked in a side aperture of the box. :

Figures 1 e 2 illustrate a connection and junction box according to the present invention, indicated as a whole with reference numeral 1.

The box 1 comprises a substantially flat bottom wall 2, substantially rectangular in shape with the smaller sides having a curved profile. A side wall 3 which defines a containing seat, open at the front, designed to contain the connections of the electrical supply cables and/or of the possible electrical switches and outlets destined to be housed in the box 1 rises from the peripheral edge of the bottom wall 2. The side wall 3 has a flat top edge 4 protruding slightly outward, designed to receive a cover in the form of a plate (per se known and therefore not shown in the figures) for closure of the box 1. From the bottom wall 2 rise two pairs of cylindrical tangs 5 which have respective through holes 6, possibly threaded, able to receive fixing means, such as screws or bolts for fixing of a cover and/or of a supporting frame for the switches and outlets. In each pair of tangs 5, the first tang is in contact with the shorter side wall of the box and the second tang is alongside the first tang in a longitudinal direction. The portions of side wall at which the tangs 5 are situated have a slot 7 designed to allow the passage of a special locking device (per se known and therefore not shown in the figures) which protrudes outward to block the box 1 to a panel of a dry wall.

A plurality of knock-out wall sections are formed in the bottom 2 and in the side wall 3 of the box. By way of example, the box 1 has eight knock-out wall sections 10. Four walls 10 are disposed in pairs in the two major sides of the side wall 3, in opposite positions to each other, and the other four wall sections 10 are disposed in the bottom wall 2 in register with the respective wall sections of the side wall 3.

As shown in Fig. 1, the profile of the wall sections 10 of the side wall 3 and of the bottom wall 2 is shaped as an arc of a circle 11 disposed distally with respect to the joining line 15 between the bottom wall and the side wall 3. The radius of curvature of the profile shaped as an arc of a circle 11 is chosen according to a minimum diameter of the corrugated conduit to be inserted in the box 1.

A larger, substantially U-shaped knock-out wall section 20 is provide around each wall section 10. The larger wall section 20 also has a profile shaped as an arc of a circle 21 coaxial and with a larger diameter than the profile shaped as an arc of a circle 11 of the smaller wall section 10. In this manner the larger wall section 20 also can be removed, so as to leave a larger aperture to receive conduits with a larger diameter.

Clearly a third substantially U-shaped wall section of a larger size than the second wall section can be provided around the larger wall section 20 and so on according to the diameter of the conduits available on the market.

As shown in Figure 3, the larger wall section 20 is slightly recessed with respect to the side wall 3 or to the bottom wall 2 and the smaller wall section is slightly recessed with respect to the larger wall section 20. In this manner, two substantially U-shaped lines of weakening 12 and 22 with a smaller thickness are formed; precisely a first profile of weakening 12 between the smaller wall 10 and the larger wall 20 and a second profile of weakening 22 between the larger wall section 20 and the side wall 3 or the bottom wall 2.

A flexible retaining tongue 30 is disposed in register with each pair of wall sections 10 disposed on the side wall and on the bottom wall, near the joining line between the side wall 3 and the bottom wall 2. As shown in Figure 3, the retaining tongue 30 is disposed substantially inclined 45° with respect to the bottom wall 2 and the side wall 3. A slot 31 is provided in the bottom wall 2, beneath the retaining tongue 30, so that the retaining tongue 30 can bend in the slot 31 and return elastically to the initial position.

Figure 3 illustrates a corrugated protective conduit 40 of the type generally used for connection of junction boxes 1. The conduit 40 is hollow on the inside to allow the passage of electrical cables to convey the electrical current. The corrugated conduit 40 has a substantially square wave shape in axial section with a plurality of protruding parts

41 alternating with a plurality of recessed parts 42. The protruding parts 41 have an outside diameter dl, whereas the recessed parts 42 have an outer diameter d2 smaller than dl.

By way of example, the corrugated conduit 40 has a minimum outside diameter, for example dl = 20 mm. hi this case, if the end of the conduit 40 is to be inserted in an aperture of the side wall 3, the smaller wall section 10 of the side wall is knocked out and removed by breaking its line of weakening 12 so as to leave an aperture in the side wall 3.

As shown in Fig. 4, the end of the conduit 40 is inserted in the aperture left in the side wall 3. Insertion of the conduit is facilitated by the inclination and possible bending of the retaining tongue 30 in the slot 31. As a result, the retaining tongue 30 tends to return elastically to the starting position and thus pushes the conduit 40 upward. Consequently it pushes the top part of the conduit 40 against the curved profile 11 which defined the smaller wall section 10.

Thus the curved profile 11 fits tightly in a recessed part 42 of the conduit 40 between two protruding parts 41. The end of the retaining tongue 30 also snap locks in a recessed part

42 of the conduit 40 between two protruding parts 41, in a position diametrically opposite the curved profile 11. In this manner the corrugated conduit 40 is firmly fixed to the box 1 and extraction or accidental release thereof is prevented by the position of the retaining tongue 30. In fact, to disengage the conduit 40 from the box 1, the user, possibly with a pointed tool, must bend the retaining tongue 30 and then pull the conduit 40. Clearly, to achieve blocking by tight fitting of the conduit 40, the thickness of the curved profile 11 which defines the aperture left by removal of the wall sections must be smaller than the width of the recessed part 42 of the corrugated conduit,

The conduit 40 can also be inserted in an aperture formed in the bottom wall 2 of the box by removing the first wall section 10 of the bottom wall 2. In this situation also, in a similar manner the conduit 40 is retained by the retaining tongue 30 which engages in a recessed part 42 between two protrusions 41 and pushes the conduit against the curved profile 11, so that said curved profile 11 engages in a recessed part 42 between two protrusions 41 of the conduit 1.

hi the event of the conduit 40 having a greater outside diameter dl, for example dl = 25 mm, the second wall section 20 of the box is knocked out and then the conduit is inserted in the aperture left by the second wall section 20 and retained by the retaining tongue 30 and by the larger diameter curved profile 21 left by knocking out of the second wall section 20.

By way of example, in the figures an arrangement of the wall sections 10, 20 has been illustrated such as to be able to exploit a single retaining tongue 30 both for the wall section on the side wall 3 and for the corresponding wall section on the bottom wall 2.

However, it is obvious that the invention is not restricted to the number of wall sections and their arrangement, hi fact the box 1 can have any number of wall sections disposed in any manner on the bottom wall 2 and/or on the side wall 3, in which each wall section 10, 20 defines a substantially curved edge 11, 21 opposite a respective retaining tongue 30.

Although in the foregoing description the retaining tongues 30 have been described as substantially elastic, they can perform their function even if they are substantially rigid.

Numerous changes and modifications of detail within the reach of a person skilled in the art can be made to the present embodiment of the invention without thereby departing from the scope of the invention as set forth in the appended claims.

Claims

1. A junction and/or switch and outlet box for electrical systems, particularly suitable to be flush-mounted in panels destined to form dry walls, said box (1) comprising: - a substantially flat bottom wall (2),

- a side wall (3) that rises from the peripheral edge of said bottom wall (2), and

- at least one knock-out wall section (10, 20), formed in said side wall (3) and/or in said bottom wall (2), designed to be removed so as to give rise to an aperture or window for insertion of the end of a corrugated protective conduit (40) wherein the electrical cables are passed, characterized in that it further comprises

- a retaining tongue (30) disposed opposite a substantially curved profile (11, 21) of said aperture formed by removal of said wall section (10, 20), so that said corrugated conduit (40) can be retained between said retaining tongue (30) and said substantially curved profile (11, 21).

2. A box according to claim 1, characterized in that said retaining tongue (30) is substantially elastic, so that it snap engages in the recessed part (42) of said corrugated conduit (40).

3. A box according to claim 1 or 2, characterized in that said retaining tongue (30) is disposed in proximity to the joining line between said bottom wall (2) and said side wall (3) and is inclined by about 45° with respect to said bottom wall (2) and said side wall (3).

4. A box according to any one of the preceding claims, characterized in that said retaining tongue (30) is disposed above a slot (31) formed in said bottom wall (2).

5. A box according to any one of the preceding claims, characterised in that said substantially curved profile (11, 21) of said aperture formed by removal of said wall section (10, 20) is of sufficiently small thickness to be blocked by fitting tightly in a recessed part (42) between two protruding parts (41) of said corrugated conduit (40).

6. A box according to any one of the preceding claims, characterized in that it comprises a smaller wall section (10) that defines a curved profile (11) having a radius of curvature chosen according to the outside diameter (dl) of corrugated conduits with a minimum diameter and a larger substantially U-shaped wall section (20) disposed around said first smaller wall section (10), in which said larger wall section (20) has a curved profile (21) coaxial with that of the smaller wall (10) and a greater radius of curvature than that of the smaller wall section chosen according to the outside diameter (dl) of corrugated conduits with a larger diameter.

7. A box according to claim 6, characterized in that said larger wall section (20) is recessed with respect to the side wall (3) or bottom wall (2) so as to give rise to a U- shaped line of weakening (22) designed to be broken to knock out the larger wall section (20), and that said smaller wall section (10) is recessed with respect to the larger wall section (20) so as to give rise to a U-shaped weakening profile (12) designed to be broken to knock out the smaller wall section (10).

8. A box according to any one of claims 3 to 7, characterized in that it comprises a first wall section (10, 20) disposed on the side wall (3) and a second wall section (10, 20) disposed on the bottom wall (2) in register with the first wall section, in which the curved profile (11, 21) of the first wall section and of the second wall section are distal with respect to the joining line between said bottom wall (2) and said side wall (3) so that both first and second wall section can exploit the same retaining tongue (30).