GB2392786A

GB2392786A - Preventing plaster entering back box

Info

Publication number: GB2392786A
Application number: GB0220391A
Authority: GB
Inventors: Andrew Charles Abbott St Swift; Darren Elliott
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-09-03
Filing date: 2002-09-03
Publication date: 2004-03-10
Anticipated expiration: 2022-09-03
Also published as: GB0220391D0; GB2392786B

Abstract

In order to prevent damage to plaster during the second fix of an electrical installation, the electrical accessory plate back boxes have a blanking insert filled into the open mouth thereof at the first fix stage. The insert also prevents plaster entering the back box. The insert is conveniently removed by breaking it and is provided with lines of weakness to aid breaking. The periphery of the insert is dimensioned to be a push fit in the back box. The inserts are provided in standard sizes to suit the sizes of back boxes that are in use.

Description

Title: Electrical installations using back box and apparatus used therein

DESCRIPTION

The present invention relates to electrical installations using back boxes and apparatus used therein.

In the erection of buildings, the installation of the electrical system is carried out in two stages referred to as the first fix and the second fix. At the first fix stage the wiring is installed and at the second fix stage the wiring is connected to the various fittings such as electrical socket outlet plates and electrical switch plates. Fittings such as these are held in place by securing them to back boxes which are fitted in place at the first fix stage before wall surfaces are finished by plastering. To facilitate plastering, the electrician will leave the tail ends of the wire coiled up in the back box.

The plaster is applied to the wall surface to finish at least level with the projecting edge of the box. However, in applying the plaster it is inevitable that plaster will also enter the back box. As a consequence, when the electrician comes to connect the wiring tails and fit the accessory plates at the second fix stage it is necessary to break away the plaster from inside the box. In doing so there is a likelihood of breaking away plaster outside of the periphery of the back box which then has to be repaired.

It is an aim of the present invention to overcome this problem.

Accordingly, a first aspect of the invention provides apparatus comprising a body member, in use, that is dimensioned to fit removably inside an open mouth of a back box.

The apparatus is hereinafter referred to as a back box insert and preferably comprises a substantially planar element. Preferably its peripheral edges are dimensioned to be a close fit with the interior surface of the walls of the back box that define the open mouth of the back box. Preferably the back box insert is a push fit in the back box. The periperal edges of the insert may be chamfered to aid insertion. The inserts are made in sizes to suit the sizes of back boxes that are in use. Two sizes of back box are in common use, i.e. single socket back boxes and double socket back boxes, and are made by various manufacturers to a "standard" size. The insert is designed to rest, in use, substantially flush with the projecting edge of the back box. In a preferred embodiment, the insert is designed to be easily and quickly removed by breaking it. To facilitate this it is preferred to provide the insert with one or more lines of weakness. These are preferably formed on one side of the insert, but may be on both sides. Preferably they are on the side that is disposed facing into the back box.

A cries-cross pattern of lines is preferred. Two lines of weakness that intersect one another in the manner of a cross may be used. Other configurations may be used.

Preferably the insert is broken by exerting a force on the insert in a direction into the back box. Because the insert lies substantially flush with the edge of the back box there will be little or no plaster overlying the insert. As a consequence of this and the fact that the insert is pushed into the box to break it, there will be a clean break of any plaster at the periphery of the back box.

Where the insert is retained in the back box as a push fit, the insert preferably has a peripheral part that grips the internal wall of the back box.

This allows a simple planar construction to be used. Alternatively, the insert may have formations on the rear face thereof that are adapted to cooperate with the screw fixing locations provided in the back box. Preferably cooperation is as a push fit, but where safety so dictates, it could utilise a screw fixing. In any event where a push fit is utilised, safety is enhanced by the presence of the insert which covers the wiring in the socket box and insofar as the push fit prevents removal without breaking the insert, safety is particularly enhanced.

In an alternative embodiment the insert is apertured to faciliate its removal. However this is less preferred as removal of the insert in one piece is liable to cause plaster to break away from around the edge of the back box. The insert is preferably made from a plastics material. A foamed PVC is particularly suitable, such as that known by the trade name FOREX, but other materials may be used. A material that is readily frangible is preferred.

The outer periphery of the insert may have a more resilient material applied thereto to enable it to cooperate sealingly with the back box and to cater for tolerance variations in the sizes of back boxes.

The present invention will now be described further, by way of example only, with reference to the accompanying drawings; in which: Figure 1 is a front view of a first embodiment of insert for a single box according to the invention, Figure 2 is a rear view of the embodiment of figure 1,

Figure 3 is a side view on A of figure 1, Figure 4 is an exploded perspective view of a single gang back box and back box insert prior to insertion.

Figure 5 is a front view of an insert for a double back box according to the invention, Figure 6 is a rear view of the embodiment of figure 5, and Figure 7 is a side view on B of figure 5.

Referring firstly to figures 1 to 3, there is illustrated a first embodiment of apparatus according to the invention. The apparatus comprises a substantially planar body 1 which is dimensioned to suit a standard single gang socket back box 3 which is illustrated in figure 4.

In this regard we find that a dimension x of approximately 69 mm x approximately 69 mm fits the standard back boxes. The front face is plain in the illustrated embodiment. The periperal edges 3, 5, 7, 9 are chamfered as noted at 11. Furthermore, the rear surface has two intersecting lines of weakness 13, 15 formed therein, conveniently as grooves. The illustration shows one example for the positioning of the lines of weakness. In an alternative the lines are diagonal and extend from the diagonally opposite corners of the body. The planar body is made from a foamed PVC and has a thickness of approximately 3 mm except where reduced to 1-2mm by the lines of weakness.

In use, the body is pushed into the open mouth of the back box (see figure 4) and is held in place by the close conformity of its periphery with the interior of the walls 17 of the back box. The presence of screw fixing lugs 21 in the back box limits the depth to which it can be pushed into the back box.

Thus a body having a thickness that is no greater than the distance that the lugs 21 are inset from the edge 23 of the back box is to be preferred.

Referring now to figures 5 to 7, there is shown an embodiment of back box insert that is dimensioned to fit a standard double socket back box (not illustrated). A dimension x, y of approximately 89 mm x approximately 129 mm has been found suitable. The features in common with the embodiment of figures 1 to 3 have corresponding reference numerals and are not described further.

The form of the lines of weakness differ from that described above and in the illustration comprise one line 17 disposed to lie intermediate the longer edges 3, 7, and two lines 19 disposed parallel to the shorter edge 5, 9 and intersecting the line 17. In an alternative, three lines of weakness are provided which each intersect the line 17. In yet another alternative, two diagonal lines of weakness are provided each of which extends between diagonally opposite corners of the body so as to intersect one another in the centre of the body.

It is used in the same way as the first described embodiment except that is it used within a double socket back box.

The inserts may be sold with the back boxes or as separate items.

The position of the lines of weakness described and illustrated herein are not to be taken as limiting.

Claims

1. Apparatus comprising a body member that, in use, is dimensioned to fit removably inside an open mouth of a back box for an electrical accessory plate.

2. Apparatus as claimed in claim 1 in which the body is a substantially planar element.

3. Apparatus as claimed in claim 1 or 2 in which the peripheral edge of the body is dimensioned to be a close fit with the interior surface of the side walls of the back box.

4. Apparatus as claimed in claims 1, 2 or 3 in which the peripheral edges of the body are chamfered.

5. Apparatus as claimed in any one of claims 1 to 4 in which the body is frangible.

6. Apparatus as claimed in any one of claims 1 to 5 in which the body is provided with lines of weakness to facilitate breaking of the body to remove it after insertion.

7. Apparatus as claimed in any one of the preceding claims in which, in use, the periphery of the body makes frictional contact with the walls of the back box to hold it in position.

8. Apparatus as claimed in any one of claims 1 to 6 in which the body has lugs that, in use, provide cooperating engagement with screw

receiving lugs of the back box.

9. Apparatus as claimed in any one of claims 1 to 6 in which the body is provided with counter sunk apertures to receive screws to secure it in position.

10. Apparatus as claimed in any of the preceding claims in which the body is made of plastics.

11. Apparatus as claimed in any one of the preceding claims in which the body is substantially rectangular.

12. An electrical accessory plate back box when provided with a blanking insert according to any of claims 1 to 9.

13. A method of temporarily sealing a back box for an electrical plate which is subsequently over laid with plaster or the like, comprising fitting a body member to the open mouth of the back box, and, after any plaster or the like has been applied, removing the body member by applying force to the body member in a direction in to the back box to break the body member into pieces and thereafter removing the broken pieces.

13. Apparatus constructed and arranged and for use substantially as hereinbefore described with reference to the accompanying drawings.

g Amendments to the claims have been filed as follows 1. Apparatus comprising a body member that, in use, is dimensioned to fit removably inside an open mouth of a back box for an electrical accessory plate and in which the body is frangible such that it breaks when sufficient force is applied to it in a direction into the back box.

2. Apparatus as claimed in claim 1 in which the body is provided with lines of weakness to facilitate breaking of the body to remove it after insertion when said force is applied to it.

3. Apparatus as claimed in claim 1 or 2 in which the body is a substantially planar element.

4. Apparatus as claimed in claim 1, 2 or 3 in which the peripheral edge of the body is dimensioned to be a close fit with the interior surface of the side walls of the back box.

5. Apparatus as claimed in any one of claims 1 to 4 in which the peripheral edges of the body are chamfered.

6. Apparatus as claimed in any one of the preceding claims in which, in use, the periphery of the body makes frictional contact with the walls of the back box to hold it in position.

7. Apparatus as claimed in any one of claims 1 to 6 in which the body has lugs that, in use, provide cooperating engagement with screw receiving lugs of the back box.

8. Apparatus as claimed in any one of claims 1 to 6 in which the body is provided with counter sunk apertures to receive screws to secure it in position. 9. Apparatus as claimed in any of the preceding claims in which the body is made of plastics.

10. Apparatus as claimed in any one of the preceding claims in which the body is substantially rectangular.

11. An electrical accessory plate back box when provided with a blanking insert according to any of claims 1 to 10.

12. Apparatus constructed and arranged and for use substantially as hereinbefore described with reference to the accompanying drawings.