FIELD OF THE INVENTION

This invention relates to back boxes for retaining electrical cabling and wiring in the space behind a wall or ceiling mounted electrical socket or switch. Back boxes are also referred to as pattress boxes for surface mounted applications and dry line or 'fast fix' for stud/plasterboard applications.

The term "back box" as used below is intended to include all such products.

BACKGROUND TO THE INVENTION

Back boxes for retaining electric cabling in a masonry background are, of course, well known and are commonly produced from a galvanised metallic material. There are several disadvantages to such boxes, these predominantly being that they are prone to corrosion, require earthing and need grommets to protect cables on the entry points. There is also the problem that they have limited fixing points with no visual opportunity to select the best option for a given substrate

In a preferred embodiment, this invention sets out to provide an electric cable back box which is non-corrosive, non- conductive, and grommet free with a clear view multi-fix rear wall providing multiple fixing points. SUMMARY OF THE INVENTION

In one aspect the invention provides a non-conductive plastics back box for electric cabling, the back box including a flexible rear wall formed with a plurality of spaced screw cups each having a transparent base.

By the term "screw cup" is meant a defined opening through which a screw can pass to secure the rear wall of the back box to a wall or ceiling surface.

In a preferred embodiment of the invention, the entire rear wall is produced from a transparent material.

Preferably, the side walls of the back box which border the flexible rear wall are relatively rigid. Preferably, the profile of the external surface of each side wall is corrugated and rounded .

Each rear and side wall of the back box preferably includes at least one opening through which electric cabling can enter the back box. Each such opening is preferably initially closed by a removable perforated slug; preferably, each said opening is formed with a raised and rounded side wall.

The plastics material from which the back box is produced is preferably a recycled plastics material.

The transparent base of each screw cup may include lines to indicate the centre of the respective screw cup. Alternatively, an opening to receive a screw may be provided on the transparent base of each screw cup.

The periphery of each screw cup preferably stands proud of the rear wall of the back box. The profile of each side wall of the back box is preferably corrugated and rounded.

In another aspect, the invention provides a non-conductive non- corrosive plastics back box for electric cabling, the back box comprising a flexible rear wall bordered by relatively rigid side walls, the rear wall including a plurality of spaced screw cups each formed of a transparent material and each able selectively to receive a screw for securing the back box to a wall or ceiling surface.

In a further aspect, the invention provides a back box for electric cabling which comprises a flexible rear wall bordered by relatively rigid side walls, the rear wall including a plurality of spaced screw cups each formed with a transparent base, whereby the position of the back box within a wall or ceiling can be adjusted by movement of one or more screws located in one or more of said screw cups.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example only with reference to the accompanying diagrammatic drawings in which

Figure 1 is an isometric view of an electric cable box in accordance with the invention;

Figures 2 and 3 are respectively front and rear views of the electric cable back box illustrated in Figure 1; and

Figures 4 and 5 are side and end views of the back box shown in Figures 1 to 3. DE TAILED DESCRIPTION OF THE INVENTION

The back box illustrated in Figures 1 to 5 is extruded or injection moulded from a plastics material (preferably a recycled plastics material) and comprises a flexible rear wall 10 bordered by relatively rigid side walls 12. Openings 14 through which electric cabling can selectively enter the back box are positioned in the rear wall 10 and each side wall 12.

Each opening 14 is initially closed by a removable perforated slug 16 and is formed with a raised and rounded side wall 17 which avoids the need for conventional grommets.

The rear wall 10 includes a multiplicity of screw cups 18 each formed with a clear view multi-fix backing plate 20. Each backing plate may be marked with lines 22 to indicate clearly the centre of the respective screw cup, or may be cut along the marked lines 22, or may include an opening to indicate the centre of the respective screw cup.

In a preferred arrangement, the entire rear wall 10 is formed of a clear plastics material.

The periphery of each screw cup is rounded and stands proud of the rear wall of the back box.

Fixings 24 to receive complementary fixings of a cover plate protrude inwardly from opposed side walls of the back box.

As will be seen from Figures 4 and 5, the external surfaces of the side walls 12 of the back box are of corrugated rounded profile .

A problem encountered when fitting a conventional back box to a wall or ceiling surface is to locate the back box accurately within an opening formed in the wall or ceiling surface so that, when fitted, the removable face plate of the box lies flush with the respective wall or ceiling surface. This problem generally occurs because of the difficulty of ensuring that the rear face of the created wall or ceiling opening is sufficiently precise to ensure that, when fitted, the face plate does lie flush with the respective wall or ceiling surface.

This problem is one of several overcome with back boxes in accordance with the invention. Thus, by locating screws in selected screw caps 18 and then moving the screws towards and away from the adjoining internal wall or ceiling surface until the back box is so positioned that when the cover plate is positioned to close the back box interior, the cover plate lies truly flush with the respective wall or ceiling surface.

Additional advantages of back boxes in accordance with the invention over conventional galvanised metallic back boxes include that they are non-conductive and non-corrosive; that they are producible from recycled HDPE plastics material; that no grommets are required when fixing the back box in place; that the flexible rear wall allows for a snug fit to the substrate to which it is to be attached whist keeping screw lugs true and eliminating the risk of cracking; that the curved and corrugated side walls give rigidity and added adhesion when bonding in; that the flexible rear wall enables a snug fit to the substrate while keeping the screw lugs true thereby eliminating or severely reducing the risk of cracking; and that the relatively transparent rear wall provides for the installer a choice of a multiplicity of fixing points to the adjoining substrate surface .

Furthermore, back boxes in accordance with the invention require no grommets, they do not require to be earthed, they will not corrode, the multi-fix rear wall enables secure and relatively problem free fixing to a wall or ceiling surface, and that they can be recycled and are fully NIC compliant. It will be appreciated that the foregoing is merely exemplary of back boxes in accordance with the invention and that modifications can readily be made thereto without departing from the scope of the invention as set out in the appended claims.