GB2170361A - Wall box - Google Patents

Abstract

A method of manufacturing a wall box (10) of the kind having a base wall (11) and side walls (12-15) defining an open mouth (17) closable by a cover (18), the method comprising the steps of, providing in or on a wall (11) of the box at least one inwardly extending locating formation (47, 48), locating an earth connector (32) by said locating formation (47, 48) and securing the earth connector (32) to the boxes by welding. The wall box may be coated e.g. with a non-conducting paint or a fine coating after the earth connector is secured to the box. The earth connector may have a bolt 37' having a threaded portion 52 and a smaller diameter unthreaded portion 53. An earth wire is held between a part 35' secured to the case and a U-shaped clamping member which has protrusions on its upper surface which, when the wire is clamped, are deformed into the smaller diameter unthreaded portion to retain the clamping member on the bolt. <IMAGE>

Description

SPECIFICATION Wall box Description of/n vention This invention relates to a method of manufacturing boxes generally known as wall boxes, for electrical installations, although it will be appreciated that such boxes need not be mounted on walls, but on any other support as desired, or even within a cavity provided in a support which opens at the surface of the support.

Such boxes are usually made from sheet metal and in use, contain electrical switches, junctions, sockets, electronic circuits, or simply provide a housing for the electrical connection of two conductors. The contents of a wall box will hereinafter be referred to as "electrical equipment".

More particularly, the invention relates to a method of manufacturing wall boxes of the kind having a base wall and side walls upstanding from the base wall, the side walls together defining an open front or mouth arranged to be closed by a separate cover plate which may be hinged thereto.

Means are provided, usually on the side walls of the box, to accommodate fixing means for retaining the cover plate in use. Such wall boxes are hereinafter referred to as being "of the kind specified".

Such a box is described in our previous U.K.

Patent No. 1,126,089. It is a requirement that such boxes of the kind specified are provided with an earth connector to which an earth conductor of the electrical equipment can be earthed, and/or another earth conductor can be connected.

Various proposals have previously been made for this purpose. In one arrangement, brass terminals are fixed in various ways to the box. In another arrangement, a tongue is bent in from a wall of the box and carries a screw, the earth connector being wrapped around the screw.

The proposals which have been made regarding separate terminals are expensive, and the use of a screw around which the wire is wrapped, does not give reliable and adequate clamping of the wire to provide good earth continuity.

Thus in some wall boxes, clamping plates are used with an earth connector and the earth conductor, or earth conductors are clamped between the earth connector and the clamping plates.

It is one object of the present invention to provide a new or improved method of manufacturing a wall box of the kind specified.

According to one aspect of the invention we provide a method of manufacturing a wall box of the kind specified comprising the steps of, providing in or on a wall of the box at least one inwardly extending locating formation, locating an earth connector by said locating formation whilst securing the earth connector to the box.

It has been found that automated assembly of the earth connector to the box is considerably facilitated by providing said inwardly extending locating formation.

Preferably, more than one such locating formation is provided, for example two locating formations, and the earth connector is of such configuration so as to be located by the locating formations engaging corresponding abutments of the earth connector.

Preferably, the earth connector is provided in a position adjacent a corner of the box so as not to interfere with electrical equipment within the box, in which case, the earth connector may be located, as it is secured to the box, by said at least one locating formation and by one or more of the walls of the box.

More preferably, the earth connector is provided on the base wall, in a corner thereof, and is located by two locating formations and two side walls of the box.

The or each locating formation is preferably provided by deforming the material of the wall inwardly.

Wall boxes of the kind specified are usually manufactured by stamping outfrom a larger sheet of metal, a plate including said side and base walls in a planar condition, and subsequently bending the side walls up to their upstanding condition, then welding, soldering, or otherwise joining each side wall, to an adjacent side wall. Forthis purpose, the side walls may be provided with integral tabs which are bent relative to their side walls to engage with said adjacent side wall.

Preferably, the locating formation is provided during said stamping manufacturing step, so that no incidental manufacturing step is required.

The electrical connector may be secured to the box by welding, preferably spot welding, to provide good earth continuity between the box, which is usually made in metal, and the connector. However, if required, other methods of securing the electrical connector to the box may be used, with electrical continuity to the box, where required, being provided by other means.

Said method may include the step of engaging a clamping member, which may be a plate or may be of saddle shape, with the earth connector, which clamping member, in use traps an earth conductor between the clamping member and the earth connector. Clamp means such as a bolt may be provided to ensure tight clamping between the clamping member and the earth connector, which bolt may pass through the clamping member, and be received in a threaded opening in the earth connector.

Said manufacturing method may include the step of applying a coating to the box, such as a paint or zinc coating. Particularly where the coating is a nonconducting paint, the paint is preferably applied subsequently to secure the earth conductor to the box, particularly where good earth continuity between the earth conductor and the box is required so that it is not necessary to remove any of the coating before securing the electrical connector in position.

Further, said coating method step is preferably carried out subsequently to engaging the clamping member and clamping means where provided, to the earth connector. In this way, when the clamping member is release, for example by a user of the box releasing the bolt to an earth conductor to be connected to the connector, the surfaces of the clamping member and earth connector which during the coating step were in contact, will be free of coating and thus good electrical connection can be achieved between the clamping member, the earth conductor and the earth connector.

According to a second aspect of the invention we provide a method of manufacturing a wall box including the step of securing an earth connectorto the box, engaging a clamping member with the earth connector, and subsequently applying a coating to the box.

The method according to the second aspect of the invention may include the steps of the method according to the first aspect of the invention.

According to a third aspect of the invention we provide a wall box of the kind specified comprising an earth connector secured inside the box on an internal wall surface of the box, in electrical conducting relationship therewith.

Preferably the box is made by a method according to the first or second aspects of the invention, and the earth connector is welded or soldered or brazed on the inside of the box.

Preferably the earth connector comprises first and second limbs, both of which are secured on the inside wall of the box, and an intermediate part between said limbs, said intermediate part being integral with the limbs but connected thereto only by a web. The intermediate part may comprise a receiving means for a clamping member and may receive a clamp means such as a bolt, to enable the clamping member to be secured to the intermediate part. Thus the intermediate part can, once the connection with the earth conductor has been made, be moved by bending said web to the position in which said electrical connection could not otherwise be made.

For example, where the earth connector is provided on a base wall in a corner of the box, preferably forming the third side of a triangle with the other two sides of the triangle being provided by the side walls of the box, the web may extend along said third triangle side to enable the intermediate part to be bent towards the corner so that the clamping member and/or clamping means can be moved into the corner of the box so as to provide maximum area for electrical equipment within the box.

In a wall box in accordance with, or made in accordance with the invention, where a clamping member is clamped to the earth connector by a clamp means comprising a bolt, it is preferred that the bolt is held captive with the clamping member to prevent the bolt and clamping member separating.

This facilitates making an earth connection with an earth conductor, and the earth connector.

Accordingly, it is another object of the present invention to provide a new or improved method of making captive a threaded fastener with a member.

According to a fourth aspect of the invention we provide a method of making captive a threaded fastener with a member, the threaded fastener having an abutment, a threaded shank, a region along the shank having a cross section reduced compared with the remainder of the shank, said method comprising the steps of, forming an opening in the member to receive the shank of the threaded fastener, deforming the material of the member adjacent the periphery of the opening to provide at least one outwardly extending tongue, inserting the threaded shank of the threaded fastener into the opening so that the abutment of the fastener engages said tongue, engaging the threaded shank in a threaded opening of a receiving means and screwing the threaded fastener into the threaded opening so that the abutment of the threaded fastener elastically urges the tongue into said region of reduced cross section.

Thus when the threaded fastener is unscrewed to release the clamping member and the receiving means, the member will be held captive on the threaded fastener by the tongue received in the region of reduced cross section of the shank.

Preferably, the threaded fastener is a bolt in which case the abutment will comprise the head of the bolt, or a washer received on the shank disposed between the head and the member.

The receiving means preferably comprises an earth connector of a wall box according to the second aspect of the invention, or a wall box made by a method according to the first or third aspects of the invention in which case, the member which is held captive may comprise a clamping member.

However, this aspect of the invention is applicable to making captive a member on a threaded fastener in many other applications.

The bolt preferably has a head formation to receive a screwdriver to facilitate tightening of the bolt sufficiently to elastically deform said tongue.

Preferably, two tongues are provided, which may be arranged on diametrically opposite sides of the opening. However, if required, more than two tongues may be provided.

The tongue or tongues may be formed prior to the opening being formed in the clamping member by pressing or stamping, or subsequently, again by pressing or stamping, or by any other means as required.

The invention will now be described with the aid of the accompanying drawings in which: FIGURE 1 is an exploded perspective view of a wall box made by a method in accordance with the invention.

FIGURE 2 is an enlarged view of part of the wall box of Figure 1 in a modified condition.

FIGURE 3 is an enlarged exploded perspective view of a clamping member and clamping means for use with the wall box of Figures 1 and 2.

FIGURE 4 is a side cross section showing a clamping means and clamping member in engagement with an earth connector.

Referring to Figure 1 of the drawings, a wall box 10 comprises a base wall 11 and four upstanding side walls 12,13,14and 15which areformed into a box-like shape, and present an opening or mouth 17. Electrical equipment such as switches, sockets, junctions, electronic circuits, or a simple connection between two conductors, may be provided within the box, and a cover 18 is provided to close the mouth 17. The cover 18 has in each corner thereof, an opening 19 through each of which, a bolt 20 passes (only one of which is shown), the bolts 20 each engaging with a fixing lug 21 provided in each corner of the box 10.

The manner by which the lugs 21 are formed will become apparent hereinafter.

The box 10 is manufactured by first stamping from a larger sheet of metal, a pattern which is in a substantialiy planar condition, and thereafter bending the side walls 12, 13, 14 and 15 relative to the base wall 11 to provide said upstanding walls.

The walls 13 and 15 each have first integral tabs 22 stamped therewith, in each corner, which tabs 22 are welded to adjacent side walls 12, 14, as shown.

The side walls 12, 14, themselves have integral tabs 23 which are welded to adjacent side walls 13,15, an upper part of which is bent perpendicularly to both walls 12, 13, and 14, 15, to provide lugs 21 to receive the bolts 20. Preferably the lugs 21 are each provided with a threaded opening 25 prior to bending to their final positions, although these openings 25 could be provided subsequently if required.

Thus when each of the tabs 22, 23, are welded to the adjacent side walls a box with considerably rigidity is provided.

It will be appreciated that if required, other means may be used for securing the side walls to one another or indeed, any other method may be provided for manufacturing a box in the general shape shown or in another configuration.

The side walls 12,13,14, l5ofthe box each have three partially cut through regions which are indicated at 26, 27, and 28. When the box is to be used, a selected one or ones of the regions 26, 27, 28, can easily be removed by punching out to facilitate the introduction of electrical conductors such as wires, or the securing to the box of conduit or the like. Region 28 is shown opened in the drawings.

The cover 18 is made as a pressing having an integral depending lip 30 which overlaps the mouth of the box to provide a seal therewith.

In one corner inside the box, an earth connector 32 is provided. As can be seen from Figure 2, the earth connector comprises a pair of side limbs 33 and 34 each of which are, in the present example, welded by a spot welding technique on the inside surface of the base wall 11 of the box, but could be brazed or soldered, or even attached with a good conducting adhesive. The connector 32 further has an integral intermediate part 35 with threaded opening 36 formed therein which opening 36, in use, receives a clamping means comprising a threaded fastener, in this example, a bolt 37, as shown in Figure 1.

The intermediate part 35 is connected to the limbs 33 and 34 by means of a web W and the intermediate parts provide a receiving means for a clamping member 38 of saddle shape having depending limbs 39 and 40. The clamping member 38 is of such configuration so as to be received over the intermediate part 35 of the earth connector 32.

The saddle shaped clamping member 38 also has an opening 41 formed therein, which when the saddle 38 is engaged with the earth connector 32, is aligned with opening 36 in the earth connector 32. Thus the bolt 37 can pass through the opening 41 and into the threaded opening 36 so that upon tightening of the bolt 37, the saddle 38 is urged into tight clamping contact with the intermediate part 35. As shown in Figure 1, earth conductors comprising wires W1 and W2 may be received between the intermediate part 35 of the earth connector 32 and the saddle 38 to provide an electrical connection between the wires W1 and W2 and the earth connector 32, when the bolt 37 is tightened. In Figure 2, the wires W1 and W2 are omitted for clarity.

Referring specifically to Figure 2, it can be seen that the limbs 33 and 34 each have an abutment surface 45 and 46 respectively which are each engaged by a locating formation 47 and 48 respectively. The locating formations 47 and 48 extend upwardly from the base 11 of the box 10, and are formed from the material of the base 11, during the stamping manufacturing operation hereinbefore described.

The purpose of the locating formations 47 and 48 is to locate the earth connector 32 whilst the limbs 33 and 34 are being spot welded or otherwise secured on the base wall 11.

It has been found that by providing such projecting locating formations, an automated welding operation is considerably facilitated.

In this arrangement, the two adjacent parts 12', 13' ofthe side walls 12,13, also provide locating formations, which are engaged by further abutments 49, 50 of the limbs 33, 34 of the earth connector 32. In another example, the earth connector 32 may be mounted away from the side walls, and located by further locating formations. In any event, more or less than two inwardly projecting locating formations may be provided, to locate the connector 32 as the connector 32 is secured in position.

Although preferably, the locating formations 47 and 48 are provided by deforming the material of the base wall 11 of the box inwardly during stamping, these could be provided by other methods if required although these may require an additional manufacturing step. The advantage of providing the formations 47,48 by deforming the material of the base wall 11 of the box is that there is no part projecting downwardly from the base which could interfere with proper seating of the box 10 on a wall or other support surface.

The box 10 is coated with a paint coating. The coating is applied subequently to welding the earth connector 32 in position so that good earth continuity is obtained between the earth connector 32 and the material of the box 10. Furthermore, preferably, the saddle 48 and bolt 37 are engaged with the intermediate part 35 of the connector 32 prior to coating, so that there is no need to remove paint from the surfaces of the intermediate part 35 or saddle 38 which during coating are in contact and engage the wires WI and W2 in use. Thus when a user comes to use the box, he simply needs to release the saddle 38 by unscrewing bolt 37, raise the saddle, and insert the wires W1 and W2 as shown in Figure 1, and retighten the bolt 37.

Referring again specifically to Figure 2, it can be seen that after said electrical connection with the wires W1 and W5 is made, that the intermediate part 35 can be bent upwardly towards corner C of the box by virtue of the intermediate part 35 being connected to the remainder of the earth connector 32 only by web W. In Figure 2, the part 35 is only shown bent to an intermediate position, although it will be appreciated that the part 35 may be bent upwardly further, so as not to obscure the adjacent opening 28 through which wires may pass into the box, through which a conduit may pass.

The connector 32 extends across corner C of the box and provides the third side of a triangle, the other two sides of the triangle being provided by side walls 12, 13. Thus the web W extends parallel to the third side, and, when the intermediate part 35 is bent into its fully bent up position, of course it would not be possible to provide said electrical connection with the wires W1 and W2 and thus the wires W, W2 must be engaged as hereinbefore described before bending the connector upwardly. Of course, it is not possible to release the bolt 37 to disengage the wires W1, W2, once the connector has been bent upwardly.

However, the position of the intermediate part 35 when fully bent upwardly is such that free entry is provided from adjacent entry region 28 without interferring with electrical equipment contained within the box 10, and a maximum free area within the box for electrical equipment is provided.

To facilitate mounting of the box 10 on its support surface, and to facilitate mounting electrical equipment within the box 10, holes h may be provided in the base wall 11 by punching out required weakened regions provided in the base wall 11.

Various modifications are possible in addition to those previously described. For example, although as described the earth connector 32 has been provided in a corner of the box and is located by two inwardly projecting locating formations 47 and 48, the earth connector may be provided in any position within the box and only one or more than two locating formations may be provided if required.

For example, the earth connector 32 may be provided on one of the side walls 12,13, 14 or 15, adjacent corner C of the box.

In piace of a saddle shaped clamping member 38, any other clamping member may be used such as that described hereinafter with reference to Figures 3 and 4, or alternatively an earth conductor such as a wire, may simply be wrapped around the bolt 37 and secured to the intermediate part 35 when the bolt 37 is tightened. One or more washers may be provided on the bolt 37 to facilitate this.

Further, if desired the box may be recessed in a cavity in a supportwhich opens out a surface thereof.

Of course, although as described the box is generally cuboid, other configurations are no doubt possible, having a base wall which in use lies adjacent a support surface such as a wall, and upstanding walls which together provide a housing for electrical equipment.

The cover 18 may be hinged to the box 10 if required, with suitable fastening means provided to retain the cover 18 in a closed position. In this event, lugs 21 may not be required. Where the box is recessed in a cavity, the cover for the mouth of the box may comprise a switch plate or socket plate to which conductors are connected.

Referring now to Figures 3 and 4, an alternative clamping member 38' to the clamping member 38 of Figures 1 and 2 is shown.

The clamping member is again saddle shaped having a pair of depending limbs 39', 40' and an opening 41' formed therein to receive a bolt 37'.

The bolt 37' is modified compared with the bolt 37 of Figures 1 and 2, in that, as can be seen from Figure 4, threaded shank 52 of the bolt has a region 53 of reduced cross section between head 54 of the bolt 37' and the remainder of the shank.

The thread is discontinued in region 53, and the reduced cross section region 53 is circular but of a reduced diameter.

The head 54 of the bolt 37' provides an abutment for a reason hereinafter explained, and is formed, in the present example, with a cross head slot formation 55 to receive a cross head type screwdriver. Of course an ordinary screwdriver slot could be provided if required.

Around the periphery of opening 41' in the clamping member 38' are two tongues 56 and 57 which are formed by stamping either prior to, or preferably subsequently to forming the opening 41'.

The tongues 56, 57, extend outwardly in an opposite direction to the limbs 39', 40'. When the shank 52 of the bolt 37' is received in the opening 41', the underside of the head 54 abuts the tongues 56, 57.

Of course if desired, a washer may be received on shank 52 between the head 54 and the tongues .56, 57, in which case, the washer would abut the tongues.

In Figure 3, part of an earth connector 32' similar to earth connector 32 of Figures 1 and 2 is shown, which connector 32' has a threaded opening 36' to receive the threaded shank 52. The earth connector 32' provides a receiving means for the clamping member 38' which as shown in Figure 4, like in Figure 2 can be received over an intermediate part 35' of the earth connector 32'. When the bolt 37' is tightened, the tongues 56, 57, will be elastically deformed downwardly as shown in Figure 4, into the reduced cross section region 53 of the shank 52.

Thus when the bolt 37' is subsequently released, the clamping member 38' will be held captive relative to the bolt 37' by the tongues 56, 57, being received in the region 53. It has been found that this considerably facilitates connection of the wires W1, W2, to the electrical connector 32' by an electrician as there is no need to raise the clamping member 38' away from the earth connector 32' when the bolt 37' has been realised, to permit of the insertion of the wires W1, W2, but the clamping member 38' raises automaticaily as the bolt 37' is unscrewed.

Of course, because the region 53 is circular around the shank, rotation of the bolt 37' is not inhibited by the tongues 56,57.

If desired, more than two tongues may be provided, or even only one tongue and although as shown in Figure 3, the tongues 56, 57, are arranged in diametrically opposite positions of the opening 41', where a plurality of tongues are provided these may be located at any desired position around the periphery of opening 41'.

This aspect of the invention is not only applicable to a bolt, but to any other threaded fastener received by a receiving means, to which fastener it is required to captively provide any member. Thus the member 38' need not be saddle shaped as described above, but could be of any other shape for example, the member may simply comprise a plate.

The receiving means need not comprise an earth connector as described above in relation to the drawings, but the receiving means may comprise any other part on which it is desired to secure a member.

Thus this aspect of the invention has application beyond wall boxes and the like with earth connectors therein but is applicable to any other threaded fastening on which it is required to captively provide a member.

Claims (1)

1. A method of manufacturing a wall box of the kind specified, comprising the steps of, providing in or on a wall of the box at least one inwardly extending locating formation, locating an earth connector by said locating formation whilst securing the earth connector to the box.

2. A method according to claim 1 wherein more than one such locating formation is provided, and the earth connector is of such configuration so as to be located by the locating formations engaging corresponding abutments of the earth connector.

3. A method according to claim 1 or claim 2 wherein the earth connector is provided in a position adjacent a corner of the box.

4. A method according to claim 3 wherein the earth connector is located, as it is secured to the box, by said at least one locating formation and by one or more of the walls of the box.

5. A method according to claim 4 wherein the earth connector is provided on the base wall, in a corner thereof, and is located by two locating formations and two side walls of the box.

6. A method according to any one of the preceding claims wherein the or each locating formation is provided by deforming the material of the wall inwardly.

7. A method according to any one of the preceding claims wherein said method includes the step of stamping out from a larger sheet of metal, a plate including said side and base walls in a planar condition, and subsequently bending the side walls up to their upstanding condition, then joining each side wall, to an adjacent side wall.

8. A method according to claim 7 wherein the side walls are provided with integral tabs which are bent relative to their side walls to engage with said adjacent wall.

9. A method according to claim 7 or claim 8 wherein the locating formation is provided during said stamping manufacturing step.

10. A method according to any one of the preceding claims wherein the electrical connector is secured to the box by welding, to provide good earth continuity between the box, which is made in metal, and the connector.

11. A method according to any one of the preceding claims wherein said method includes the step of engaging a clamping member, with the earth connector, which clamping member, in use traps an earth conductor between the clampirrg member and the earth connector.

13. A method according to claim 11 or claim 12 wherein clamp means comprising a bolt passes through the clamping member, and is received in a threaded opening in the earth connector.

14. A method according to any one of the preceding claims including the step of applying a coating to the box.

15. A method according to claim 14 wherein said coating method step is carried out subsequently to engaging the clamping member and clamping means where provided, to the earth connector.

16. A method of manufacturing a wall box including the steps of securing an earth connectorto the box, engaging a clamping member with the earth connector, and subsequently applying a coating to the box.

17. A method according to claim 16 including any of the steps of the method according to any one of claims 1 to 16.

18. A method of manufacturing a wall box substantially as hereinbefore described with reference to the accompanying drawings.

19. A wall box of the kind specified comprising an earth connector secured inside the box on an internal wall surface of the box, in electrical conducting relationship therewith.

20. A box according to claim 19 wherein the box is made by a method according to any one of claims 1 to 18.

21. A box according to claim 20 wherein the earth connector is welded or soldered or brazed on the inside of the box.

22. A box according to claim 20 or claim 21 wherein the earth connector comprises first and second limbs, both of which are secured on the inside wall of the box, and an intermediate part between said limbs, said intermediate part being integral with the limbs but connected thereto only byaweb.

23. A box according to claim 22 wherein the intermediate part comprises a receiving means for a clamping member and a clamp means to enable the clamping member to be secured to the intermediate part.

24. A box according to claim 22 or claim 23 wherein the earth connector is provided on a base wall in a corner of the box, forming the third side of a triangle with the other two sides of the triangle being provided by the side walls of the box, the web extending along said third triangle side to enable the intermediate partto be bent towards the corner so that the clamping member and/or clamping means can be moved into the corner of the box so as to provide maximum area for electrical equipment within the box.

25. A wall box substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

26. A method of making captive a threaded fastener with a member, the threaded fastener having an abutment, a threaded shank, a region along the shank having a cross section reduced compared with the remainder of the shank, said method comprising the steps of, forming an opening in the member to receive the shank of the threaded fastener, deforming the material of the member adjacent the periphery of the opening to provide at least one outwardly extending tongue, inserting the threaded shank of the threaded fastener into the opening so that the abutment of the fastener engages said tongue, engaging the threaded shank in a threaded opening of a receiving means and screwing the threaded fastener into the threaded opening so that the abutment of the threaded fastener elastically urges the tongue into said region of reduced cross section.

27. A method according to claim 26 werein the threaded fastener is a bolt.

28. A method according to claim 27 or claim 28 wherein the receiving means comprises an earth connector of a wall box according to any one of claims 19 to 25, or a wall box made by a method according to any one of claims 1 to 18.

29. A method according to claim 26, claim 27, or claim,28, wherein two tongues are provided.

30. A method according to claim 29 wherein the two tongues are arranged on diametrically opposite sides of the opening.

31. Any novel feature or novel combination of features disclosed herein and/or as shown in the accompanying drawings.