GB2352470A

GB2352470A - Shield for electrical back box

Info

Publication number: GB2352470A
Application number: GB0014860A
Authority: GB
Inventors: Witold Gamski
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-06-17
Filing date: 2000-06-16
Publication date: 2001-01-31
Also published as: GB0014860D0; GB9914204D0

Abstract

A temporary shield 9 for protecting an electrical back box (1, Fig 7) from ingress of building material, such as plaster, during building work. The shield 9 comprises a frame member 10 which in use provides an extension to the side wall or walls of the box and flange means 15 for retaining the frame member. The frame member may include an inner face (20, Fig 17) which is preferably hinged by a flexible strip (not shown). During use, the back box is mounted in the wall, the shield is attached, the surrounding wall is plastered, and finally the shield is removed.

Description

2352470 Shield The present invention relates to a shield for the

protection of electrical back boxes during finishing of a surface such as a wall, floor or ceiling.

A power point typically comprises a box with a detachable lid, the box being used to house the electrical wires and 'mount' an electrical socket connected to the wires on a wall, floor or ceiling. The so-called mounting or 'back' box is usually made of metal and has a generally rectangular shape with a back face, four side walls upstanding io from the back face, and an open face opposite the back face. For aesthetic reasons, the box is usually fitted with its open face Rush with the exposed surface of the wall so that the box does not project out of the plane of the wall. The back face and/or sides of the box have means for creating one or more openings through which electrical wires may be threaded. The wires -protrude into the box and are connected to the back of a socket. The socket provides the lid of the back box and is secured to the back box by screws, thus hiding and protecting the wires inside the box. A similar such arrangement is provided for electrical switches, such as light switches, cooker points, etc. Instead of the lid of the back box comprising the socket means, it comprises switching means for creating or breaking an electrical connection between the wires and a light fitting or other appliance. The term 'power point' or 'socket' as used hereinafter is therefore intended also to embrace electrical switches.

During building construction or building refurbishment, new or replacement power points are usually installed prior to surface finishing. In this regard, Figures I to 3 illustrate a method of finishing a surface such as a wall in which a power point is located. Once the position of the power point has been decided, an electrician will fit a back box I into the wall 2 and pull the wires 3 through at least one opening 4 in the back face 5 of the box I so the wires 3 project into the box I (Figure 1). When the box I has been fitted, a plasterer will skim the wall 2 with plaster 6 (Figure 2). For flush mounted sockets, it is difficult and therefore time consuming for the plasterer to provide a level finish without at least some plaster entering the box 1. After plastering, the electrician will return to fix the wires 3 to surface socket 7. As the box 1 will undoubtedly have been at least partially covered over or filled with plaster 6, the I electrician must then locate the extent of the box I and remove the excess plaster 6 from the box 1, particularly from the screw holes used to mount the socket and from the wires themselves. More often than not, the plaster 6 is chipped away to an extent which is greater than the area of the box 1, leaving unsightly gaps or holes 8 which must be filled (Figure 3). A decorator will then paint or decorate the finished wall, but must fill in the holes 8 where the plaster 6 has been chipped away by the electrician before he can begin his task.

It can be appreciated that providing a neat finish around a quantity of electrical back io boxes is time-consuming for the plasterer, frustrating for the decorator because it is seen as the plasterer's job, and perhaps even more frustrating for the electrician who must spend time cleaning up the boxes and wires before he can properly and safely wire and fit the sockets. Accordingly, the aim of the present invention is to provide a means whereby the aforementioned problems are eliminated or at least substantially reduced.

To this end, the present invention resides in a temporary shield for protecting an electrical back box from substantial ingress of building material, such as plaster, during building work, the shield comprising a frame member which in use provides an extension to the side wall or walls of the box and means for retaining the frame member substantially contiguous with the box walls.

By means of the present invention, the side wall or walls of the back box are effectively lengthened such that they project out beyond the surface, usually a wall, in which the box is mounted and provide a barrier around which the plasterer is forced to work. Moreover, by virtue of the frame member extending from and contiguous with the wall or walls of the back box, the shield also acts as a guide for the plasterer assisting him to form a neat plaster edge around the box.

Where the back box is a generally rectangular shape, as is the case for the majority of such boxes fitted in the United Kingdom, the frame member will also be rectangular, mirroring the perimeter walls of the box. However, it will be appreciated that other shapes may be used, for example, the back box may be circular, in which case the 2 frame member would comprise an annular band. Thus whatever the peripheral shape of the back box, the frame will provide a continuous extension to its side wall(s).

Since the shield is intended only as a temporary measure, and is required to be easily removed after plastering around the box, the fi-ame member is ideally retained by means which co-operate with the interior of the box, otherwise the retaining means will be plastered over and hence it will be difficult to remove the shield without damaging the applied plaster.

In one arrangement, the retaining means may comprise a skirt which depends from the frame member and which co-operates with the interior of the back box. Wule such a skirt may be held against the interior of the box by adhesive means, for example, by use of one or more adhesive pads affixed to the outer face of the skirt and initially protected before use by a release layer, the use of an adhesive is not particularly convenient either in terms of manufacturing the shield or in terms of fitting the shield over the box.

Accordingly, in order to retain the frame member against the edge of the side walls of the back box, the skirt most conveniently offers a friction fit with the box's internal side walls. More preferably, the skirt is outwardly flared and preferably resiliently connected to the frame member. In this way, the skirt may be compressed or '4squeezed" during insertion in the box and, once inserted, flexes outwards such that it is retained by friction against the internal walls of the box. A further benefit of such an arrangement is that the friction fit minimises the amount of extraneous plaster which may slip into the box if the shield is knocked during plastering, displacing the frame member so that contact with the box walls is momentarily lost.

Instead of a continuous skirt, the retaining means may instead comprise a plurality of flanges which depend from the frame member. For rectangular back boxes, it is preferred that there are at least two flanges which depend from corresponding edges of oppositely disposed frame walls. More preferably, however, one flange is provided for each of the side walls of the back box and each flange extends across substantially the whole length of its corresponding box wall, again minimising the amount of 3 extraneous plaster which may enter the box if the frame is accidentally displaced. To allow for positioning of the frame and retention in its place, it is again advantageous if the flanges bear against the internal side walls of the back box. A further advantage is seen if the flanges are flexible, because this facilitates insertion of the flanges into the 5 box.

Alternatively, the flanges may depend from two or more, preferably all, comers of the frame walls to aid location of and hold the frame within the back box. These comer flanges may be substantially triangular, the apex of the triangle at the junction between adjoining walls, such an arrangement again facilitating insertion of the flanges into the box.

In a further alternative, or in addition for example where the one or more flanges extend across only part of the corresponding box wall, the frame may include retaining means in the form of engaging means to secure the frame to the back box. Preferably, the engaging means are shaped to engage with internal features, such as mouldings of the back box. The screw flanges which are often provided for fixing the cover or lid to the box are particularly suitable for this purpose. For example, the engaging means may mate with internal mouldings by snap fitting so that insertion and retention is made easy. On the other hand, accidental removal or displacement of the shield is made more difficult. Indeed, removal of the shield after use may involve breaking or snapping off of the engaging means.

When a back box is mounted in a surface such as a wall, the required number of electrical wires are pulled through at least one opening in the back wall and/or sides so that they project into the back box. In order to provide maximum tolerance for connecting the wires to terminals on the back of a socket, it is usual to leave long lengths of the wires. This also enhances identification of the location of power points once a wall has been plastered. Therefore, it is advantageous if the shield is hollow to accommodate the wires. In this respect, the frame member and retaining means preferably combine to form a cavity in which the electrical wires can be accommodated. While the cavity may be closed by an outer face to prevent plaster entering the shield, it is further preferred that the outer face includes an opening. In 4 this way, any length of wires left by the electrician can be accommodated. For example, the wires can be wound inside the cavity or allowed to protrude beyond the outer extent of the shield.

The shield may be closed by an inner face to retain wires within the back box and hence fiu-ther protect them from stray plaster. Optionally, the inner face may comprise a flap adapted to be opened and provide a degree of flexible space for the wires if their length is too great to be comfortably accommodated wholly within the back box behind the flap. The flap is preferably attached to the frame by a hinge, such as in the form of a flexible strip bridging the two parts. In this way, the wires are permitted to protrude into the shield while remaining at least partially protected. Also, a flexible strip provides a line of weakness which allows the user to open or remove the flap altogether to allow the wires to protrude out of the back box and shield, especially if the length of wire is too long to be accommodated within the back box and/or shield.

To facilitate handling of the shield by the user and to allow the plasterer easy access around the exterior of the frame, the walls of the frame member may taper inwardly away from the box such that the frame member narrows at the edge ftuthest from the box.

Alternatively, the walls of the frame member may taper outwardly such that the frame member widens at the edge fin-thest from the box in order to define more clearly an edge around which a plasterer may work.

Although users may wish to retain and re-use a shield after use, it is envisaged that the shield is disposed of after use. To this extent, it is preferred that the shield is moulded from a relatively inexpensive material, such as a plastic. For ease for manufacture it is preferred that the shield is moulded as one piece. In this way, the shield may be supplied at a fraction of the cost of the power point itself, but its major benefit arises from the cost saving in terms of the electrician's and decorator's time as they are no longer required to chip out and/or refill the plaster around the box.

To enable the shield to fimction reliably in the manner envisaged, it is advantageous if the plastic has the desired combination of flexibility and rigidity. Such characteristics will enable the shield to be fitted onto an electrical back box with ease and ensure that the shield withstands flexing, attack by building implements and the weight of any 5 plaster which may fall on to it.

To reduce the possibility of any plaster surrounding the back box and in contact with the shield from being peeled/chipped off when the shield is removed from the back box, it is advantageous if the shield is adapted to prevent plaster from adhering to shield. For example, the shield may be moulded from a material, such as a plastic, which is inherently non-adhesive to plaster or contains a release agent, for example, silicone, to prevent such adhesion. Alternatively, the exterior of the shield may be coated with a release agent.

Where the shield has a closed or partially closed inner face, it is advantageous if the material from which the shield is moulded is suitable to be trimmed easily with a knife. In this way, a plasterer may additionally use the shield as a depth gauge for plastering around the box while the box is protected from any stray plaster.

The invention also encompasses a method of finishing a surface, such as a wall, comprising the steps of mounting an electrical back box in the wall, protecting the box by a shield as hereinbefore described, plastering the wall surrounding the back box, and removing the shield.

The shield and its use will now be described in more detail with reference to the accompanying drawings.

Figures I to 3 show a known method of finishing a wall surrounding an electrical back box and fitting a surface socket to the back box.

Figures 4 to 6 illustrate a shield in accordance with a first embodiment of the invention wherein Figure 4 shows a perspective view, Figure 5 shows a side view, and Figure 6 shows a view ftom above.

6 Figures 7 to 12 illustrate a method of finishing a wall in accordance with the invention; Figure 8 is a section view showing the shield in use.

Figures 13 to 17 illustrate a second embodiment of the invention wherein Figure 13 shows a perspective view, Figure 14 shows a view from one side, Figure 15 shows a cross-section view along line XV-XV shown in Figure 13, Figure 16 shows a view from above and Figure 17 shows a cross-section along line XVII-XVII shown in Figure 16.

Figure 18 illustrates how a shield in accordance with the second embodiment of the invention is located into a single back box, while Figure 19 illustrates how a similar shield with a closed inner face is located into a double back box.

Referring to Figures 4 to 6, the shield 9 has a frame member 10 comprising a continuous wall which provides a generally rectangular box with four sides 16. The frame member 10 has an inner edge I I and an outer edge 12 in use and tapers inwardly from the inner edge I I to the outer edge 12 so that the frame member 10 narrows towards the outer edge 12.

The outer edge 12 defines an enclosing boundary of the outer face 13 which is square in shape. The outer face 13 does not provide a complete surface but defines a border around a rectangular opening 14.

Retention means in the form of flanges 15 depend from the inner edge 11 of each side 16 of the frame member 10. Each flange 15 is rectangular and extends along the greater part of the inner edge I I of each side 16. The flange 15 is curved outwardly having a concave semi-circular curve in the region where the flange 15 connects to the inner edge 11 of the frame member 10, and then extends outwardly in a substantially linear fashion.

The embodiment shown is for use with a single socket back box. Accordingly the shield 9 has dimensions which are suitable for such a box 1. In this respect, the length 7 of each side 16 is 73min at the inner edge 11. Each side 16 extends from the inner edge 11 to the outer edge 12 by between approximately 35mm to 50mm, and narrows to the extent that the length of each side 16 is 68mm at the outer edge 12. Each flange 15 extends partially along the inner edge I I of each side 16 by 65mm and depends from the inner edge I I by I Omm. The outer face 13 has a border which is I Omm in width, fonning a generally square opening which is 48min square. The dimensions specified are, of course, merely preferred and the illustrated embodiment should not be construed as being limited to these dimensions.

The overall size of the shield 9 may be extended for use with a double socket back box, and indeed for any suitable shape of back box. For example, a shield 9 for a double socket back box will have two oppositely facing sides 16 which are 133MM in length, while the other two sides 16 are 73mm in length.

A method of finishing a wall using a shield according to Figures 4 to 6 will now be described, referring to Figures 7 to 12.

First (Figure 7), a back box I is mounted in the desired location on a wall 2 and the electrical wires 3 are pulled through an opening 4 created in the back face 5 of the box 1. The shield 9 is fitted onto the box 1, and the wires 3 are pulled through the opening 13 in the outer face 12 of the shield 9 (see Figures 8 and 9).

To fit the shield 9 onto the box 1, the frame member 10 is partially squeezed together in the region of the inner edge 11 of at least two sides 16. This brings the flanges 15 towards each other so they may be inserted easily into the box 1.

Referring to Figure 8, the shield 9 is fitted so that the flanges 15 are located inside the box 1 and bear against the interior of the walls 17 of the box I to retain the shield 9 in place. The inner edge I I of each side 16 of the frame member 10 sits on the top of the walls 17 of the box I thus providing a barrier against ingress of plaster. The frame member 10 extends beyond the surface of the building wall 2 to accommodate the lengths of electrical wires 3. The wires 3 may be retained within the box I and shield 8 9 or, as shown in Figure 8, threaded through the opening 14 in the outer face 13 to protrude out of the shield 9.

Figure 9 shows a wall 2 ready for finishing with a shield 9 in situ on the back box 1.

The wall 2 is then skimmed with plaster 6 (Figure 10) with the back box I being protected from the ingress of plaster by the presence of the shield 9. Once decorating, such as painting and/or papering, has been completed, the decorated wall is ready to receive the socket 7. The shield 9 is removed before or after decorating whereupon it may be disposed of, leaving the back box 1 free of plaster 6 and circumscribed by a neat edge of plaster 6 (Figure 11). The electrical wires 3 may then be easily and safely connected to the socket 7 (Figure 12).

A second embodiment of the invention is shown in Figures 13 to 19 which will now be described using the same reference numbering as before for corresponding features.

As with the first embodiment, the shield 9 has a frame member 10 comprising a continuous wall which provides a generally rectangular open box with four sides 16. The ftarne member 10 has an inner edge 11 and an outer edge 12 in use and tapers outwardly from the inner edge I I to the outer edge 12 so that the frame member 10 widens towards the outer edge 12.

The inner edge 11 defines an enclosing boundary of an inner face 20 which is square in shape. The inner face 20 does not provide a complete surface but defines a border around a rectangular opening 14. The inner face 20 is shaped to provide a degree of protection to the box I and any wires 3 which may be retained within the box 1. As shown in Figure 17, the inner face 20 has a horizontal portion which turns vertically to protrude from the horizontal plane of the inner face 20. This shaping provides added protection for the box I and any wires 3 within the box 1.

The embodiment shown in Figure 19 has a substantially complete inner face 20 which is attached along one edge only by a flexible strip (not shown), thereby providing the user with the option to retain the complete inner face 20 yet will allow it to pivot outwards from the box or remove it altogether so that wires 3 can protrude from the box I into the shield 9 and beyond.

9 Locating means in the form of triangular flanges 15 depend from the inner edge I I of each side 16 at the comers of the frame member 10. Two flanges are arranged in each comer with their apexes meeting to form a right angle at the lowest point from the inner edge 11.

The frame 16 also has retention means in the form of pairs of engaging means 30 which depend substantially vertically from the inner edge 11 of oppositely disposed sides 16. The engaging means 30 are shaped to snap fit around mouldings, such as screw flanges 32, within the back box I and act to hold the shield 9 against the back box 1. In the embodiment shown, the engaging means 30 are located along the inner edge 11 so they correspond with a screw flange 32 and are elongate in shape, with each engaging means 30 having a protruding ledge 34. The protruding ledge 34 snaps into place underneath a screw flange 32 when the shield 9 is pushed into the back box 1. The engaging means 30 are designed so that when the shield 9 is no longer required, it may simply be pulled out of the back box I without having to be removed with the aid of tools. While only two pairs of engaging means 30 are shown in Figures 13, 15 and 17, further pairs may be provided.

As with the first embodiment, the second embodiment shown is for use with a single socket back box. Accordingly the shield 9 has dimensions which are suitable for such a box I and thus are similar to those described for the first embodiment, namely the length of each side 16 is 73mm at the inner edge 11, each side 16 extends from the inner edge 11 to the outer edge 12 by between approximately 35mm to 50nim, and widens to the extent that the length of each side 16 is 78mm at the outer edge 12. Each flange 15 extends from each comer partially along the inner edge 11 of each side 16 by 15mm and depends from the inner edge 11 by l2mm. The inner face 20 has a border which is I Omm in width, forming a generally square opening which is 40mm square. The dimensions specified are, of course, merely preferred and the illustrated embodiment should not be construed as being limited to these dimensions.

As with the first embodiment, the overall size of the shield 9 may be extended for use with a double socket back box, and indeed for any suitable shape or type of back box.

For example, a shield 9 for a double socket back box will have two oppositely facing sides 16 which are 133mm in length, while the other two sides 16 are 73mm in length.

Figures 18 and 19 show how a shield 9 is located within single and double back boxes 1 respectively. In Figure 18, the shield 9 has two pairs of engaging means 30 disposed on oppositely facing sides 16, and four locating means 15 which fit snugly into each comer of the box 1. The shield 9 has open outer and inner faces 13, 20 to allow wires 3 located in the box I to protrude into, and if necessary beyond, the shield 9. In Figure 19, the shield 9 is essentially the same, although shaped to fit a double box 1.

However, the shield 9 has a closed inner face 20 to retain wires 3 within the box 1 and shield 9. In the event that the wires 3 are too long to be retained within the box 1, the inner face 20 is hinged (not shown) so that it may be opened, at least partially, to allow the wires to project into and possibly out of the space bounded by the frame member 10.

It will be appreciated that the present invention may be embodied in other specific forms without departing from the essential attributes thereof. For example, the shield may also be used to protect a back box during decorating, such as painting and/or papering, of a wall. The shield is intended for use by both professional and amateur people.

While it is envisaged that the shield is mainly for use with back boxes mounted in walls, the shield may also provide protection against the substantial ingress of other building materials such as concrete when the back box is mounted, for example, in a floor or ceiling.

The shield described is preferably moulded from plastic so that it may be disposable and inexpensive. However, it may be preferable in some instances that the shield is not disposable. In this way, for example, the shield could be made from a suitable metal and cleaned after use. As with a plastic shield, the metal could be sprayed with a release agent, such as silicone, before use so that any plaster which may be adhere to the shield in use can be easily removed.

Claims

Claims:

1. A temporary shield for protecting an electrical back box from substantial ingress of building material, such as plaster, during building work, comprising a frame member which in use provides an extension to the side wall or walls of the back box, and means for retaining the frame member substantially contiguous with the wall or walls of the back box.

2. A temporary shield as claimed in claim 1, wherein the retaining means co-operates 10 with the interior of the back box.

3. A temporary shield as claimed in claim 2, wherein the retaining means bears against the internal side walls of the back box.

4. A temporary shield as claimed in claim 3, wherein the retaining means offers a friction fit with the internal side walls of the back box.

5. A temporary shield as claimed in claim 4, wherein the retaining means is outwardly flared.

6. A temporary shield as claimed in any one of claims I to 5, wherein the retaining means is resiliently connected to the frame member.

7. A temporary shield as claimed in any one of claims I to 6, wherein the retaining 25 means comprises a skirt which depends from the frame member.

8. A temporary shield as claimed in any one of claims 1 to 6, wherein the retaining means comprises a plurality of Ranges which depend from the frame member.

9. A temporary shield as claimed in claim 8, wherein the retaining means comprises at least two flanges which depend from corresponding edges of oppositely disposed walls of the frame member.

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10. A temporary shield as claimed in any one of claims 1 to 4, wherein the retaining means comprises engaging means which engage with internal features of the back box.

11. A temporary shield as claimed in claim 10, wherein the engaging means engage with internal features by snap fitting.

12. A temporary shield as claimed in any preceding claim, wherein the frame includes 10 locating means.

13. A temporary shield as claimed in claim 12, wherein the locating means comprises a plurality of flanges which depend from the frame member.

14. A temporary shield as claimed in claim 13, wherein the flanges depend from two or more comers of the frame.

15. A temporary shield as claimed in claim 13, wherein the flanges are substantially triangular.

16. A temporary shield as claimed in any preceding claim, wherein the frame member, defines a cavity which is closed by an inner face.

17. A temporary shield as claimed in claim 16, wherein the inner face is closed by a 25 flap adapted to be opened.

18. A temporary shield as claimed in claim 17, wherein the flap is attached to the frame by a hinge.

19. A temporary shield as claimed in claim 18, wherein the hinge is a flexible strip.

20. A temporary shield as claimed in any preceding claim, wherein the walls of the frame member taper outwardly away from the back box when in use.

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21. A temporary shield as claimed in any preceding claim, wherein the frame,. -%ber is rectangular.

22. A temporary shield as claimed in any preceding claim, wherein the shield is moulded as one piece and is made of plastic.

23. A temporary shield as claimed in claim 22, wherein the plastic contains, or is coated with, a release agent.

24. A temporary shield as claimed in claim 23, wherein the release agent is a silicone.

25. A method of finishing a surface, such as a wall, comprising the steps of mounting a back box in the wall, at least partially protecting the back box by a shield as claimed in any preceding claim, plastering the wall surrounding the back box, and removing the shield.

26. A temporary shield substantially as hereinbefore described with reference to Figures 4, 5, 6 and 8, Figures 13 to 17, Figure 18 or Figure 19 of the accompanying drawings.

27. A method of finishing a surface, such as a wall, substantially as hereinbefore described with reference to Figures 7 to 12 of the accompanying drawings.

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