GB2440468A

GB2440468A - Electrical back box having resilient lug on peripheral flange for securing a cover

Info

Publication number: GB2440468A
Application number: GB0721059A
Authority: GB
Inventors: Jason Berry
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-02-12
Filing date: 2004-02-12
Publication date: 2008-01-30
Anticipated expiration: 2024-02-12
Also published as: GB2440468B; GB0721059D0

Abstract

An electrical pattress box 7 comprises a back panel 8 and one or more side walls 10 wherein the cross sectional area bound by the wall or walls is circular or is the shape of an area defined by two or more semi-circular areas having a rectangular area between them, the straight edges of the semi-circular areas corresponding to sides of the rectangular area. At least one peripheral flange 12 is provided with a lug 15 adjacent an aperture 16 which provides resilient movement of the cover engaging protuberance 15. A cover 17 may be provided with a hole 20 to snap onto engagement lug 15. Installation is facilitated by exclusive or predominant use of a tool for cutting circular holes. If the back box is circular then a lower portion of the side wall may be provided with integral cutting teeth providing a self-cutting pattress box.

Description

Electrical back box

Field of the invention

The invention relates to electrical back boxes used in the building trade in many electrical sockets and fittings.

Background to the invention

The present invention relates to an electrical back box, also known as a pattress, having improved installation characteristics. Electrical installations, for example, switches, sockets and fuse boxes, require the use of back boxes which fulfil two functions. Firstly, they hold circuitry and wiring in place. Secondly, they supply a support means to which the back box cover can be fixedly attached.

Back boxes accommodated in a recess or hole in a wall have a standard format. They are rectangular e.g. square in cross section taking on a cuboid shape in three dimensions. The back box comprises a rectangular back panel and four side walls, each side wall attached to an edge of the back panel. In use, a rectangular hole is made in the wall to accommodate the back box. The box is positioned in the hole with the open face of the box flush with the surface of the wall.

S... The back panel and/or one or more side walls may be provided with a hole or perforations facilitating the formation of a hole through which electrical cabling can be passed into the box. Other holes may be provided through which fastening means e.g. screws can be passed in order to attach the : box to the wall.

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A cover for the box e.g. a switch cover or socket cover is required and usually comprises a front panel and one or more side walls containing the

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appropriate electrical switching, electrical socket or other mechanism.

Alternatively, in some instances, a blank cover containing no mechanism may be required. The rear of the cover is open and, following installation of the box and any necessary connection of electrical cabling to a mechanism in the cover, the cover is placed over and attached to the box or to the wall resulting in occlusion of the box from view. Attachment of the cover to the box may be accomplished using screws inserted through screw-holes present in the cover into threaded screw sockets present in the box.

Alternatively, the cover may be screwed directly into the wall.

Back boxes are generally made of a sturdy and durable material, such as metal or plastic.

A problem associated with the use of the known back box occurs during its installation. The creation of the rectangular hole to accommodate the standard back box is labour intensive and time consuming due to the requirement to hand chisel part of or the entire hole. This invention relates to a back box modified to accommodate easier installation and fixing.

The invention also provides a combination of back box and cover wherein the cover can be more easily attached to the back box.

:. Brief summary of the invention * *** **** * * *S*.

The present invention and its preferred embodiments seek to overcome or mitigate the problems of the prior art. A significant problem of the prior art is the necessary generation of a rectangular hole in the wall, or other surface, *:::: during the installation of the back box, which is labour intensive. The *:*. current invention removes this obstacle by providing a back box designed to be installed into a hole entirely or substantially produced using a cutting tool for cutting a circular hole. A single circular hole may be used.

Alternatively, two or more adjacent or overlapping circular holes may be drilled with subsequent removal of small remaining pieces of wall present between the boundaries of the two or more circles, to produce the hole required by a back box in accordance with the invention.

According to one aspect, the invention provides an electrical back box comprising a back panel and one or more side walls characterised in that the cross-sectional area bound by the wall or walls is substantially circular or is substantially the shape of an area defined by two or more semi-circular areas having a rectangular area between them, the straight edges of the semi-circular areas corresponding to sides of the rectangular area between them, wherein the side wall or walls, have one or more flanges extending substantially perpendicularly from the wall or walls at or adjacent the edge of the wall or walls distant from the back panel and extending away from the opening defined by the edge, wherein at least one lug extends from the edge of the flange in the plane of the flange, wherein the lug is adjacent to an aperture in the flange facilitating resilient movement of the lug in the plane of the flange towards the edge of the opening.

According to another aspect, the invention provides a combination of the back box and a cover for the back box, said cover comprising a front panel and one or more side walls. * * * *..

* Brief description of the drawings *. ****

Figure Ia is an isometnc view of a back box of the invention; *:" Figure lb is a side elevation of the box shown in Figure Ia; Figure Ic is a plan view of the box shown in Figure Ia; Figure 2a is an isometric view of another back box of the invention; * Figure 2b is an end elevation of the box shown in Figure 2a; Figure 2c is a side elevation of the box shown in Figure 2a; Figure 2d is a plan view of the box shown in Figure 2a; Figure 3a is an isometric view of a cover for the box shown in Figures 2a to 2d; Figure 3b is an end elevation of the cover shown in Figure 3a; Figure 4a is a isometric view of a self-cutting back box of the invention; Figure 4b is a side elevation of the box shown in Figure 4a; Figure 4c is a plan view of the box shown in Figure 4a;

Detailed description of the invention

In a particularly preferred embodiment of the invention, the side wall or walls of the back box have one or more flanges extending substantially perpendicularly from the wall or walls at or adjacent the edge of the wall or walls distant from the back panel, the flange or flanges extending away from the opening defined by the edge. An advantage of this feature is that it can prevent the installation of the back box too far into the wall as the box can only be inserted until the flange comes into contact with the surface of the wall. This is particularly advantageous when the box is to be fitted in a wall having a thickness less than the depth of the box. A further advantage of the flange is that it can provide a means of attaching the box to the wall and/or a means of attaching a cover to the box. I. * *

Preferably, the back box comprises a continuous flange around the edge of **** the opening. **** * * S...

In order to facilitate the attachment of a cover to the back box, the box may *:::: comprise at least one lug extending from the edge of the flange in the plane of the flange. In a preferred embodiment, the lug is adjacent an aperture in * the flange facilitating resilient movement of the lug in the plane of the flange towards the edge of the opening. Two lugs may be present, one on an opposite side of the opening of the box to the other.

Alternatively or additionally, the back panel of the back box may be provided with fastener receiving means enabling, when in use, the fastening of a cover to the back box. The fastener receiving means may comprise one or more threaded sockets for receiving threaded bolts passed through the cover.

The flange may comprise at least one hole through which fastening means e.g. a screw can be passed enabling fastening of the flange to a wall.

In a preferred embodiment of the invention, a self-cutting back box is provided. In this embodiment, the back box has a side wall wherein the cross sectional area bound by the wall is circular and wherein the box is provided with means for cutting a circular hole substantially co-extensive with the circular cross sectional area bound by the side wall. Preferably, the side wall extends beyond the back panel and is provided with said cutting means e.g. cutting teeth at the end of the wall. In a preferred embodiment, the teeth are an integral part of the side wall.

The self-cutting back box preferably further comprises means for enabling rotation of the box about an axis parallel to the side wall and passing through the centre of the cross sectional area of the box. The means for enabling rotation of the box may comprise a shaft attached to the back panel that extends into the box. By attaching an electric drill to the shaft, the box can be rotated thereby cutting its own circular hole through a wall.

It will be readily apparent that alternative means of attaching a drill to the boxcanbeused. * *

Although the cross sectional area of the back box may be circular, the **** * : outline presented by the outer edge of the flange may be different. For *..: example, the outline of the flange may be substantially circular or substantially square.

In another preferred embodiment of the invention, the back box has a side wall wherein the cross sectional area bound by the wall is substantially the shape of an area defined by two semi-circular areas having a rectangular area between them, the straight edges of the semi-circular areas corresponding to parallel sides of the rectangular area. Such a box can accommodate multiple sockets or switches.

In order to facilitate the drilling of circular holes in the optimum locations in a wall, the exterior wall of the back panel of the back box may be provided with a marker positioned at the centre of each circular area partially defined by each semi-circular area.

The back box of the invention may be made of any suitable durable material, preferably plastics material or metal. It is particularly advantageous for the box to be made of a plastics material from which it can be moulded.

The invention also provides a combination of a back box as hereinbefore described and a cover for the back box, said cover comprising a front panel and one or more side walls.

Preferably, the back box comprises a flange and the area defined by the :. inner edge or edges of the side wall or walls at the opening of the cover is substantially co-extensive with the area defined by the outer edge or edges of the flange of the back box. *

* * 30 **** In a particularly preferred combination, the back box is provided with at * , ** least one lug extending from the edge of the flange in the plane of the :::: : flange and the cover is provided with a hole for receiving each lug such * that, when in use, the cover can be snap-fitted to the box.

Various embodiments of the present invention will now be described, by way of example, with reference to the drawings.

Figures Ia to ic show an electrical back box having a substantially circular back panel 2 and a side wall 3. The cross sectional area bound by the side wall 3 is circular. The back panel is substantially closed, except for a hole 4 through which electrical cabling can be passed into the box. The box may contain additional features not shown, for example and without limitation, additional holes, fixing means and mouldings, some of which may extend into the back box. A continuous flange 5 is present and protrudes from the edge of the side wall farthest from the back panel at an angle that is perpendicular to the side wall. The flange is continuous and surrounds the opening of the box. The outline presented by the outer edge of the flange is substantially square, more particularly square with rounded corners.

Alternatively, the outline could be substantially circular and of slightly greater diameter than the diameter of the circular cross section of the side wall from which the flange extends. The flange contains screw holes 6 such that the back box can be fixedly attached to the wall once installed. In this embodiment, four screw holes are present but any number could be included. In an alternative embodiment, the flange could be provided with one or more lugs protruding from its outer edge.

The back box is preferably made from suitable materials chosen from plastics and metals, but could also be made from other materials obvious to :. one skilled in the art. The flange is preferably made from the same material as the back box back panel and side wall and preferably forms a continuous unit with them such that the back box is of integral construction. a * S S...

According to another embodiment, the back box may be of a different cross sectional shape also provided to be installed by the predominant use of a S..

tool for cutting circular holes, where more than one circular hole needs to be produced. In this embodiment, a back box is provided for larger installations, such as but not limited to, double electrical sockets. In Figures 2a to 2d, a back box 7 is illustrated suitable for housing a double socket.

The cross sectional area bound by the side waIl 10 and the shape of the back panel 8 is defined by two semi-circular areas separated by a substantially rectangular area, e.g. rectangular or square, where the width of the rectangular area corresponds to the diameter of the semi-circular areas, and where the sides of the rectangle correspond to the straight edges of the semi-circular areas. In this preferred embodiment the straight edges of the semi-circular areas correspond to parallel sides of the rectangular area. In alternative embodiments, the cross sectional area bound by the side wall may be the the shape of an area defined by more than two semi-circular areas having a rectangular area between them, the straight edges of the semi-circular areas corresponding to more than two sides of the rectangular area.

The back panel 8 comprises two screw holes 9 for fixing the back box to the wall, but additional features may also be present, for example but without limitation, additional holes, fixing means and mouldings, some of which may extend into the back box. The back panel 8 is bound by a side waIl 10 which contains a hole 11 through which electrical cabling may be threaded. It should be noted that there may be one or more holes, on one or more sides of the side wall and that they may take on multiple forms obvious to one skilled in the art.

Flanges 12 are present at either end of the back box corresponding to the :. semi-circular regions. Each flange extends substantially perpendicularly from the side wall at the edge of the wall distant from the back panel. The flange contains holes 13 through which a fastening means may be passed for fixing the back box to the wall. Each flange is provided with a lug 15 extending from the edge of the flange in the plane of the flange. Each flange is also provided with an arcuate aperture 16 adjacent the lug 15.

The aperture facilitates resilient movement of the lug in the plane of the flange towards the opening of the back box.

The exterior surface of the back panel 8 is provided with a marker 14 positioned at the centre of each of the circular areas partially defined by each semi-circular area such that the centres of the two circular holes to be cut into the wall can be perfectly aligned and marked on the wall prior to cutting by pushing the back box against the wall so that the markers leave a mark e.g. an indentation in the wall. In this instance, each marker 14 is a protrusion on the back wall but may be of a different form which would be obvious to one skilled in the art.

Figures 3a and 3b show a cover suitable for attachment to the back box shown in Figures 2a to 2d. The cover 17 comprises a front panel 18 and a side wall 19. The area defined by the inner edge of the side wall at the opening of the cover 17 is substantially co-extensive with the area defined by the outer edge of the flange and opening of the back box 7. In other words, the cover is shaped to fit closely over the back box. The side wall 19 of the cover is provided with a hole 20 at each end of the cover, the position of each hole 20 corresponding to the position of each lug 15 on the back box when the cover is attached to the back box. By pushing the cover over the back box, each lug 15 is pushed inwardly towards the opening of the back box until it is aligned with a hole 20 when it is able to resume its original position by entering the hole. In this way, the cover can be releasably snap-fitted to the back box.

The front panel 18 of the cover 17 comprises holes 21 which may be, as in figure 3, suitable for a double electrical socket, but could be for many other sockets and switches and the like known to one skilled in the art.

In another aspect the invention provides a circular back box, shown in *.e.

Figures 4a to 4c, wherein the back box is adapted to include a cutting tool to provide a self-cutting back box 22. The back box 22 is capable of cutting S.S* a circular hole which is substantially co-extensive with the circular cross sectional area bound by the side wall 27 of the back box. The back box 22 comprises a continuous circular flange 23. It should be noted that an alternatively shaped flange, e,g, substantially square or rectangular, may be present as may be multiple flanges or the flange may be completely absent. The continuous circular flange 23 is adapted for use with a circular snap cover such that an aperture 24 is present in the flange adjacent a lug on each side of the back box. Holes e.g. hole 26, are also present in the flange 23 through which fastening means can be passed for fixedly attaching the back box to the wall. In the embodiment shown, three holes are present for use with screws, positioned equidistantly around the flange 23. The side wall 27 extends beyond the exterior surface of back panel of the back box and is provided with a cutting means 28 at the end of the side wall. The cutting means 28 comprises a plurality of cutting teeth formed in the extended section of the side wall 27. In alternative embodiments, the cutting means could be any other means suitable for cutting into a wall obvious to one skilled in the art e.g. a single sharpened edge continuous around the circumference of the side wall.

To operate the self cutting back box to produce a circular hole, the said back box must be rotated at speed by the attachment of a suitable tool, for example but without limitation, a hand held electric drill. In the embodiment shown, the back box comprises a means 29 for facilitating rotation of the back box about an axis parallel to the side wall and passing through the centre of the cross sectional area bound by the side wall. This is provided by a shaft 29 having a hexagonal cross section attached to the interior surface of the back panel and extending into the box. The shaft may be of any suitable design to permit the attachment of an electrical drill. The shaft is preferably made of the same material as the back box such that it is *::::* moulded as one piece, but it may alternatively be made of a different suitable material and attached to the back box by any suitable and known means. *

*:::: The back box shown in Figures 4a to 4c is particularly suitable for installation in walls having a thickness less than the depth of the box e.g. a dry lining or plasterboard wall.

Back boxes of the invention may be installed more efficiently than conventional back boxes. For boxes having a circular cross section, a circular hole is drilled in the wall into which the box fits. Alternatively, several circular holes may be drilled with minimal removal of additional material to accommodate the other back boxes of the invention. For certain walls including dry lining and plasterboard walls the box may be held in position adequately by being a tight fit in the hole as shown in other embodiments. Alternatively or additionally, in other embodiments of the present invention, the box may be attached to the wall by other means.

One or more flanges at the opening of the box facilitate correct positioning of the box. The flange(s) can also provide means of snap fitting a cover to the box. * * * *** **** * * **** S... * . *5*S

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Claims

Claims 1. An electrical back box comprising a back panel and one or

more side walls characterised in that the cross sectional area bound by the wall or walls is substantially circular or is substantially the shape of an area defined by two or more semi-circular areas having a rectangular area between them, the straight edges of the semi-circular areas corresponding to sides of the rectangular area, wherein the side wall or walls have one or more flanges extending substantially perpendicularly from the wall or walls at or adjacent the edge of the wall or walls distant from the back panel and extending away from the opening defined by the edge, wherein at least one lug extends from the edge of the flange in the plane of the flange, wherein the lug is adjacent an aperture in the flange facilitating resilient movement of the lug in the plane of the flange towards the edge of the opening
2. A back box according to claim I comprising a continuous flange around the edge of the opening.
3. A back box according to claim 2 wherein two lugs are present, one on an opposite side of the opening to the other. * . * ***

*:::: 4. A back box according to any one of the preceding claims wherein the flange comprises at least one hole through which fastening means can be passed enabling fastening of the flange to a wall. b... * *

:. 5. A back box according to any one of the preceding claims wherein the back panel is provided with fastener receiving means enabling, when in use, the fastening of a cover to the back box.

6. A back box according to claim 5 wherein the fastener receiving means comprises one or more threaded sockets.

7. A back box according to any one of the preceding claims having a side wall wherein the cross sectional area bound by the wall is circular and wherein the box is provided with means for cutting a circular hole substantially co-extensive with the circular cross sectional area bound by the side wall.

8. A back box according to claim 7 wherein the side wall extends beyond the back panel and is provided with said cutting means at the end of the wall.

9. A back box according to claim 8 wherein the cutting means comprises cutting teeth.

10. A back box according to claim 9 wherein the teeth are an integral part of the side wall.

11. A back box according to claim 6 wherein the exterior wall of the back panel is provided with a marker positioned at the centre of each circular area partially defined by each semi-circular area.

12. A back box according to any one of the preceding claims made of plastics material or metal. * S.. *

13. A back box according to claim 12 moulded from plastics material.

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14. The combination of a back box according to any one of the *:*. preceding claims and a cover for the back box, said cover comprising a front panel and one or more side walls.

15. The combination according to claim 14 wherein the back box comprises a flange and the area defined by the inner edge or edges of the side wall or walls at the opening of the cover is substantially co-extensive with the area defined by the outer edge or edges of the flange of the back box.

16. The combination according to claim 15 wherein the back box is provided with at least one lug extending from the edge of the flange in the plane of the flange and the cover is provided with a hole for receiving each lug such that, when in use, the cover can be snap-fitted to the box. * * * ..* **.. * * **** s.* * . S...

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Amendments to the claims have been filed as follows Claims 1. An electrical back box comprising a back panel and one or more side walls charactensed in that the cross sectional area bound by the wall or walls is substantially circular or is substantially the shape of an area defined by two or more semi-circular areas having a rectangular area between them, the straight edges of the semi-circular areas corresponding to sides of the rectangular area, wherein the side wall or walls have one or more flanges extending substantially perpendicularly from the wall or walls at or adjacent the edge of the wall or walls distant from the back panel and extending away from the opening defined by the edge, wherein at least one lug extends from the edge of the flange in the plane of the flange, wherein the lug is adjacent an aperture in the flange facilitating resilient movement of the lug in the plane of the flange towards the edge of the opening 2. A back box according to claim I comprising a continuous flange around the edge of the opening.

3. A back box according to claim 2 wherein two lugs are present, one on an opposite side of the opening to the other. S...

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4. A back box according to any one of the preceding claims wherein the flange comprises at least one hole through which fastening means can be passed enabling fastening of the flange to a wall.

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5. A back box according to any one of the preceding claims wherein the back panel is provided with fastener receiving means enabling, when in use, the fastening of a cover to the back box.

6. A back box according to claim 5 wherein the fastener receiving means comprises one or more threaded sockets. -i

7. A back box according to claim 6 wherein the exterior wall of the back panel is provided with a marker positioned at the centre of each circular area partially defined by each semi-circular area.

8. A back box according to any one of the preceding claims made of plastics material or metal.

9. A back box according to claim 8 moulded from plastics material.

10. The combination of a back box according to any one of the preceding claims and a cover for the back box, said cover comprising a front panel and one or more side walls.

II. The combination according to claim 10 wherein the area defined by the inner edge or edges of the side wall or walls at the opening of the cover is substantially co-extensive with the area defined by the outer edge or edges of the flange of the back box.

12. The combination according to claim 11 wherein the cover is provided with a hole for receiving each lug such that, when in use, the cover can be snap-fitted to the box. * **S S. S * * * .. * S.... * S

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