GB2432265A

GB2432265A - Mounting box for electrical wiring accessories

Info

Publication number: GB2432265A
Application number: GB0617696A
Authority: GB
Inventors: Pierre Deleplanque; Keith Wray Ball; Terence Edward John Lovett; Andrew Purdie Baker
Original assignee: Schneider Electric Ltd
Current assignee: Schneider Electric Ltd
Priority date: 2005-09-10
Filing date: 2006-09-08
Publication date: 2007-05-16
Anticipated expiration: 2026-09-08
Also published as: GB0617696D0; GB2432265B

Abstract

A mounting box 10 for an electrical wiring accessory 12 is adapted to fit through an aperture 20 in a panel 14. It has an open front side for receiving the accessory and access for electrical connections toward a rear side, and also has at least one retractable clamping part 22 and an actuator 24 to clamp the clamping part against the rear of the panel to secure the mounting box in place. The actuator is accessible and operable from at least one of the rear and the front of the mounting box with said accessory already in place, so as to permit the box and the accessory to be pre-assembled off-site and secured in said aperture as a unit. The wiring to the accessory may be a plug-in connection, see figure 2.

Description

MOUNTING BOX FOR ELECTRICAL WIRING

ACCESSORIES AND ASSEMBLIES AND INSTALLATIONS

INCLUDING SUCH MOUNTING BOX

The invention relates to electrical wiring accessories, in particular to accessories accompanied by a plastic or metal flush wall mounting box.

Mounting boxes for filling electrical accessories such as power outlet sockets/light switches and the like are well known. These boxes are fitted into either a solid brick or plastered wall, or a hollow plasterboard, or similar style wall. In the case of solid walls, the boxes are usually fixed by means of screws into the wall through the rear wall of the box. In the case of plasterboard hollow walls, some form of flexible clip or bracket is used to grip the rear of the wall board, the box being inserted into the wall from the front. The accessory with its facia is then connected to wiring and filled into the mounting box, covering the front of the box and being secured, typically with a pair of standard screws.

For large commercial installations, there is nowadays the option to use pre-fabricated wiring with plugged connections, for example of the WIELAND GESIS type. The advantage is that the final installation work can be performed more quickly and, to some extent, by less skilled personnel than conventional wiring installation. Testing of the connections can largely be performed at the factory.

Particularly when a building is being constructed or re-fitted, there is relatively easy access to the interiors cavities of walls, floors and ceilings.

Nevertheless, the known accessory/mounting box designs all require a relatively labour-intensive process of fitting of the open mounting box, connecting the accessory electrically and screwing the accessory into place over the box opening. While plastic quick-fit alternatives might be considered, experience with the clip-in type of mounting box mentioned above suggests that such solutions are not robust enough to provide the desirable high levels of ruggedness, security and safety.

It is accordingly an object of the invention to enable the provision of an electrical wiring accessory and mounting box, which is suitable for fitting to a hollow wall and which provides a rugged and secure mounting while achieving a significant labour saving over known systems. The terms "front", "forward" and "rear" are used below as if the accessory is in place in a wall, facing towards a user, and should be interpreted figuratively when the assembly is not mounted, or is mounted in a floor or ceiling, for

example.

Our co-pending patent application GBO51 8497.3 (Agent's ref 65171GB), from which priority is claimed herein and the content of which has not been published at the present filing date) describes a mounting box provided with retractable clamping parts and actuators which are accessible and readily operable from the rear of the mounting box with said accessory already in place, so as to permit the box and accessory to be pre-assembled off-site and secured in said aperture as a unit.

The present invention in a first aspect provides in combination an electrical wiring accessory and a mounting box for the accessory, the mounting box being adapted for fitting through an aperture in a panel and having an open front side for receiving the accessory and access for electrical connections toward a rear side thereof, the mounting box being further provided with at least one retractable clamping part and an actuator operable to deploy the retractable clamping part to apply pressure against the rear of the panel to secure the mounting box in place, said actuator being accessible and operable from at least one of the rear and the front of the mounting box with said accessory already in place, so as to permit the box and accessory to be pre-assembled off-site and secured in said aperture as a unit.

The actuator will preferably be accessible from both front and rear of the unit comprising mounting box and accessory assembled together.

The accessory will typically include a face plate spanning the front of the mounting box when assembled into said unit, in which case an aperture may be provided in the face plate for access to the actuator from the front side of the unit.

Alternatively, the actuator may be accessible only from the rear in the assembled condition, and operable from the front side of the box, on condition that said accessory is removed.

The operation of said actuator and clamping part is preferably reversible.

In preferred embodiments, the clamping part has the form of a cam, or short arm, rotation of the actuator during installation serving to swing said clamping part positively from a retracted to a deployed orientation.

In one embodiment, the clamping part is a cam having a ramp profile for pressing progressively on the rear of the panel as it is rotated from the retracted orientation, the actuator and cam rotating in unison. The maximum rotation of the actuator and cam may be less than three quarters of a revolution.

The cam (including in this context the actuator coupled to the cam) and mounting box may be provided with complementary formations for engaging one another to prevent accidental retraction of the clamp. The formations may be arranged to operate at several intermediate orientations between fully retracted and fully deployed orientations of the cam.

The actuator may alternatively be a lead screw serving firstly to swing said clamping part into a deployed orientation and then to advance the clamping part toward the front side of the mounting box. This type is slower to operate but may adapt to a wider range of panel thicknesses than the simple cam.

The lead screw may be provided at both ends with slots or other formations to permit rotation.

The lead screw may have a head providing a larger formation at an end toward the rear of the mounting box.

Alternative forms of clamping part, such as pivoting flanges, may be envisaged also.

The actuator, be it a lead screw or whatever,may be formed to require a tool different from a conventional screwdriver to be operated from at least one the front side. Requiring a hex key, for example, will discourage accidental demounting of the whole assembly from the wall, where slotted screws are provided for demounting the accessory from the mounting box for maintenance.

In a preferred embodiment, a further clamping part and actuator are provided at a location on the periphery of said mounting box generally opposite the first clamping part, thereby to press at two places on the wall panel.

The axis of rotation of the or each actuator may be arranged parallel to a respective mounting screw by which the accessory will be assembled to the mounting box.

Said access for electrical connections may comprise a connector for making a plugged connection with wiring behind the panel.

Said connector may be adapted for direct pluggable connection to the accessory when the latter mounted on the front side of the box.

Alternatively, the connector may be connectable to the accessory by short wiring. Particular forms of pluggable connector are described in another co-pending application number GB 0600943.5 (Agent's Ref 65261GB), also not published at the present filing date or priority date.

The combination may be in pre-assembled form with said electrical connections already made from the rear of the mounting box to the accessory by the above or other means.

Based on these features, the embodiments of the invention as described below provide an arrangement, which can be easily fitted during initial assembly, but more importantly can be mounted as a complete assembly with the accessory top already fitted and wired. The accessory and mounting box can also easily be removed from the wall at a later date for maintenance purposes of the cabling assemblies, and if necessary be re-fitted. Also the embodiments provide a firm fixing to the wall which can only he removed by means of a tool, for example a screwdriver.

The invention also provides methods of pre-assembly and methods of installation of electrical wiring accessories based on the features set forth above.

A first method according to the invention comprises assembling a unit comprising an electrical wiring accessory and a mounting box of the combination set forth above such that electrical connection to the accessory can be made without disassembly of the unit, the actuator for the clamping part is accessible without disassembly of the unit, and the unit is not mounted on any panel.

A second method comprises providing a combination of wiring accessory and mounting box as set forth above assembled in a unit, fitting the unit into a wail panel aperture by operation of the actuator to clamp the unit to the wall and making electrical connection between the accessory and supply wiring behind the panel, all without disassembly of the unit.

The invention in a second aspect provides a mounting box for an electrical wiring accessory, the mounting box being adapted for fitting through an aperture in a panel and having an open front side for receiving the accessory and access for electrical connections toward a rear side thereof, the mounting box being further provided with at least one retractable clamping part and an actuator operable to deploy the retractable clamping part to apply pressure against the rear of the panel to secure the mounting box in place, said actuator being accessible and readily operable from the rear of the mounting box with said accessory already in place, so as to permit the box and accessory to be pre-assembled off-site and secured in said aperture as a unit.

The actuator may further be accessible and operable from the front side of the box, either on condition that said accessory is removed or via an aperture in a faceplate of a compatible accessory in the combination as described above.

Embodiments of the invention will now be described, by way of example only, by reference to the accompanying drawings, in which: Figure 1 shows in cut-away detail the rear of a novel accessory/mounting box assembly being fitted in an aperture in a wall board with operation of clamping parts from the rear; Figure 2 shows a similar assembly to that of Figure 1 from the front with clamping device retracted prior to fitting, including apertures for operation of said clamping mechanism from the front, and also shows an example of pluggable wiring in place; Figure 3 shows a similar assembly from the front, with clamping device deployed; Figure 4 is an exploded view of the assembly shown in Figures 1 and 2; Figure 5 shows an assembly similar to that of Figure 4, but in a version having a wired internal connection instead of the pluggable connection; Figure 6 shows an assembly of an electrical wiring accessory and a mounting box according to a second embodiment of the invention; Figure 7 illustrates assembly of a clamping mechanism in the assembly of Figure 6; Figure 8 shows in more detail a gripper part of the mechanism (a) from the front and (b) from the rear; Figure 9 shows the clamping mechanism from the interior of the mounting box; and Figure 10 is a cross-section of the assembly of Figures 6 to 9 mounted in a wall panel.

Referring to the first embodiment, it will ease understanding to consider Figures 1 to 4 together, while specific features will be mentioned with reference to particular drawings as appropriate. The drawings show an assembly of a novel mounting box 10 and electrical accessory 12 mounted through a wall panel 14 such as plasterboard. A flange 11 runs around the mouth of the mounting box, to prevent the box falling backwards through the aperture. The panel 14 will typically be one side of a double-sided cavity wall where the electrical cables run. However, when a building is being fitted for the first time, or being radically re-fitted, the rear of panel 14 may be fully accessible because the other panel of the cavity wall is not yet fitted. Wires 15, 15' within the walls of a building are coupled to the accessory by means of rear socket block 16 projecting from the mounting IJJA.

From the front at least, the accessory in this case is substantially a standard switched mains outlet socket (UK 13 amp standard, single or dual type), but other accessories including different types of outlets, isolators, light switches and so on can all be envisaged as part of the same system. The terms "front", "forward" and "rear" are used as if the accessory is in place in a wall, facing towards a user, and should be interpreted figuratively when the assembly is not mounted, or is mounted in a floor or ceiling, for example. In a preferred embodiment, the faceplate of the accessory is modified by the provision of apertures, the position and purpose of which will be described further below. Novel arrangements for making electrical connections to the accessory may also be provided, as described more fully in the co-pending application number GB 0600943.5 (Agent's Ref 65261 GB), mentioned above.

A clamping mechanism is provided in the side wall at each end of the mounting box 10, and comprises primarily a clamping arm 22 and an actuator in the form of lead screw 24. The box side wall includes a slot or recess 26 allowing the arms 22 to swing into a retracted position within the box. A stop 28 engages part of the box to limit the retraction once the arm is flush with the sides of the box 10. Each lead screw 24 has a slotted head readily accessible at the rear side of the box 10, and is free to rotate while being restrained axially by a circlip 30 (visible in Figure 3). The clamping arm 22 is internally threaded, and forms a friction fit onto the threaded lead screw. As seen in Figure 4, with the accessory removed from the front of the mounting box 10, each lead screw 24 also has a slot 32 at its forward end. The lead screw is supported at the top by means of moulded support with hole. Threaded bosses 34 are provided on standard centres for receiving the mounting screws 35 of the accessory 12 in the usual manner.

Figure 1 shows how the novel accessory mounting box 10 can be fitted onto wall panel 14 open from the rear, even when the accessory 12 and box 10 are pre-assembled with connections made internally between the accessory and the connector 16. The box is fitted through aperture 20 in the wall panel 14, the lead screw 24 is turned by means of a screwdriver 36, which will cause the clamping arm 22 to swing outwards behind the plasterboard panel 14. Further turning of the lead screw will cause the clamping arm to rise and tighten against the rear of the panel 14, the front of which is trapped under the peripheral flange 11.

It can be seen that the actuator, in this case lead screw 24, is fully accessible from the rear of the mounting box, even when assembled together with the accessory already in place. Furthermore, in this preferred embodiment, the faceplate of accessory 12 includes apertures 37 aligned with the lead screws 34 to provide access for a screwdriver to the slot 32 of each one.

It can now be seen that, where a hollow double-sided wall is being used then the complete wired accessory with box can be inserted through the aperture in the wall panel and then tightened by operation of the lead screws 34 to deploy the clamping arms 22. This operation of the lead screws can be performed either from the rear, as seen in Figure 1, or from the front through the apertures 37, all without disassembling the accessory and mounting box. The rear wiring is then attached to the rear socket block 16. In order to remove the box from the wall for maintenance purposes it is merely necessary to rotate the lead screws 24 in the opposite direction to release the clamping arm 22, and return it to its resting position inside the box, If the rear of the box is still accessible, this can be done with a screwdriver exactly as shown in Figure 1, or it can be done from the front through apertures 37.

In an alternative embodiment, where standard accessories without apertures 37 are used, operation of the lead screws from the rear is still possible. If the rear of the panel 14 is no longer accessible, then the top of the accessory 12 can be removed from the front of the mounting box by undoing screws 35 in the conventional manner, whereupon access to the forward slot 32 of each lead screw is possible from inside the box.

Describing the Figures individually, Figure 2 shows the assembly 10, 12 with a plug 16 connecting wire 15 to the accessory via socket block 16.

The clamping arm 22 is shown retracted. Note that, in this embodiment, plug 18 must be removed for the head of the lead screw 24 to be accessible from the rear.

As seen in Figure 3, when the clamping arm 22 has exited from the slot 26 it comes to rest against the end wall of the box 10. Further rotation of the lead screw will then cause the clamping arm to move along the lead screw towards the front plate of the accessory 12. A second plug 18' and wire 15' are shown, as would be used if the accessory were on a ring main.

Figure 4 shows further advantageous features within the accessory and mounting box assembly. This shows an arrangement whereby fitting and removal of the accessory 12 is made easier by replacing a wired connection to the lower plug/socket by the provision of a further pluggable connector. A range of accessories can be manufactured with pluggable connectors 38 compatible with mating connectors 40 on the rear socket block 16, mounted in the rear wall of box 10, so that these mate automatically on assembly of the accessory 12 to the mounting box 10.

More variations and detailed discussion of these plugging arrangements are provided in the co-pending application number GB 0600943.5 (Agent's Ref 65261GB), mentioned above.

For maintenance or replacement of the accessory, the top cover is removed by undoing the two fixing screws 35 and then lifting upwards to disengage the connectors 38, 40. If the mounting box is also to be removed from the wall, the lead screws can then be operated using slots 32 to retract the clamping arms 22 from behind the wall panel.

Alternatively, to remove the complete assembly from the hollow wall, the lead screws 24 are operated via apertures 37 as already described.

Alternatively, where access is available from the rear, the wiring plugs 18, 18' can be removed and the two lead-screws 24 operated from the rear as shown in Figure 1. Note that male and female connectors are provided on opposite sides of socket block 16, so that the wires 15, 15' can be patched together by their plugs 18, 18'. As a further option, socket block 16 may be detachable from the rear of the box 10 so that the box can then be removed from the wall to reveal the cabling connectors within the wall.

Figure 5 shows a version where the pluggable connectors 38, 40 are not provided and more conventional wiring is provided within the assembly to connect the electrical parts of the accessory 12 to the socket block 16.

The second embodiment shown is Figures 6 to 10 has a similar form and operates on very similar principles to the first embodiment just described and only the differences between them will be described in detail. The same reference numerals are used for similar parts, prefixed 1', so that the mounting box is 110, the accessory is 112 and so forth.

Figure 6 shows a completely assembled accessory box 110 with accessory 112 fitted. The clamping part or gripper 122 is generally in the form of a cam, different from the swing arms 22 of the first embodiment, as will be explained in more detail below. Cam 122 is shown in the deployed position, as it would be behind the wall. Aperture 137 in the front cover enables access, such that a suitable tool can be inserted to actuate the gripper, It will be understood that matching grippers 122 are provide at both ends fo the box, although only one fo these will be shown and discussed in further detail. Two apertures are provided for the usual cover-to-box fixing screws 135.

Figure 7 shows how each gripper 122 is inserted into the box on assembly. Recess 126 in the side wall of the box 110 allows the gripper part to be inserted from the outside. It is then fixed into position by means of the locking pieces 150.

Figure 8(a) and (b) are detailed views of the gripper 122. The forward facing surface 152 of the gripper is angled away from the front of the box toward the end of a projecting arm, such that, as the gripper is rotated further into deployment, surface 152 presses more tightly against the wall.

Instead of a lead screw passing through the gripper 122, actuator in this embodiment is an integral shaft 124 provided with a hexagonal hole, which travels the full length. In addition, the outside of each end 154 and 156 of the shaft is also provided with a hexagon. This allows two types of tool to be used for rotation, but not a simple screwdriver. Bearing surfaces are shown 158 and 160 which fit closely against matching bearing surfaces above and below the recess 126. A cut-out 162 is provided to allow the gripper to be rotated past the cover fixing screw 135. Two pips 164 are provided on the underside of the cam, as seen in Figure 8 (b).

Figure 9 shows the internal form of the box with the gripper assembly in place and, for the sake of illustration, in the deployed orientation. The forward end 154 of gripper shaft 124 is located in part 168 such that it is held firmly but able to rotate on the bearing surfaces mentioned above. A similar location is provided at the rearward end. A series of click-stop holes locate with the moulded pips 164 on the underside of the gripper. This provides a positive location once positioned in the wall, preventing the gripper twisting back toward the retracted position without deliberate operation. The cover fixing screw hole is shown at 134.

Figure 10 shows the box 110 and typical accessory 112 assembly fitted onto a wall 114. Chain-dotted line segments 172 and 174 show the axis of rotation of a tool to disengage the box from the wall, by rotating the gripper 122 from in front or behind the wall, respectively.

In all of the examples shown, the novel mounting box provides additional flexibility for pre-assembly and rapid installation, while retaining the familiarity, security and compatibility of conventional mounting systems.

The concept of providing the mounting box with a pluggable connector for pre-assembled wiring adds flexibility also, and can be extended to include pluggable connections between the mounting box and the accessory itself, using suitably modified accessories. The requirement for cutting wires, stripping insulation and making screw terminal connections can be completely eliminated if desired.

Further modifications are of course possible within the spirit and scope of the invention in its various aspects, and the examples illustrated and described above are not to be taken as limiting on the scope of protection sought. The exact form of the mounting box and accessories can vary according to the application, national standards and so forth. The accessory 12 may be entirely integrated with the front cover plate, as shown, or the assembly may come in three parts, with the cover plate separate from the working parts of the accessory. The accessory may in other instances comprise only a cover plate, where a mounting box and connections are provided to allow for some future requirement.

Claims

CLAIMS

1. In combination an electrical wiring accessory and a mounting box for the accessory, the mounting box being adapted for fitting through an aperture in a panel and having an open front side for receiving the accessory and access for electrical connections toward a rear side thereof, the mounting box being further provided with at least one retractable clamping part and an actuator operable to deploy the retractable clamping part to apply pressure against the rear of the panel to secure the mounting box in place, said actuator being accessible and operable from at least one of the rear and the front of the mounting box with said accessory already in place, so as to permit the box and accessory to be pre-assembled off-site and secured in said aperture as a unit.

2. A combination as claimed in claim 1 wherein the actuator is accessible from both front and rear of the unit comprising mounting box and accessory assembled together.

3. A combination as claimed in claim 2 wherein the accessory includes a face plate spanning the front of the mounting box when assembled into said unit, and an aperture is provided in the face plate for access to the actuator from the front side of the unit.

4. A combination as claimed in claim 1 wherein the actuator is accessible only from the rear in the assembled condition, and operable from the front side of the box, on condition that said accessory is removed.

5. A combination as claimed in any of claims 1 to 4 wherein the operation of said actuator and clamping part is reversible.

6. A combination as claimed in any of claims 1 to 5 wherein the clamping part has the form of a cam or short arm, rotation of the actuator during installation serving to swing said clamping part positively from a retracted to a deployed orientation.

7. A combination as claimed in claim 6 wherein the clamping part is a cam having a ramp profi!e for pressing progressively on the rear of the panel as it is rotated from the retracted orientation, the actuator and cam rotating in unison.

8. A combination as claimed in claim 6 or 7 wherein the maximum rotation of the actuator and cam is less than three quarters of a revolution.

9. A combination as claimed in claim 6, 7 or 8 wherein one of the cam and the actuator coupled to the cam and the mounting box are provided with complementary formations for engaging one another to prevent accidental retraction of the clamping part.

10. A combination as claimed in any of claims I to 6 wherein the actuator is a lead screw serving firstly to swing said clamping part into a deployed orientation and then to advance the clamping part toward the front side of the mounting box.

11. A combination as claimed in claim 10 wherein the lead screw is provided at both ends with slots or other formations to permit rotation.

12. A combination as claimed in claim 10 or 11 wherein the lead screw has a head providing a larger formation at an end toward the rear of the mounting box. I-'

13. A combination as claimed in any of claims 1 to 12 wherein the actuator is formed to require a tool different from a conventional screwdriver to be operated from at least one the front side.

14. A combination as claimed in any of claims I to 13 wherein a further clamping part and actuator are provided at a location on the periphery of 1......, Pu.. :&.. it...... (...., .u..........:..... LL........t-...

IU 111UU11U119 UUA yeuueu uuy uppuit LuI uIIL iuiqiuiiy Jc1uI., tiiiiiy tU press at two places on the wall panel.

15. A combination as claimed in any of claims Ito 4 wherein the axis of rotation of the or each actuator is arranged parallel to a respective mounting screw by which the accessory will be assembled to the mounting box.

16. A combination as claimed in any of claims 1 to 15 wherein said access for electrical connections comprises a connector for making a plugged connection with wiring behind the panel.

17. A combination as claimed in claim 16 wherein said connector is adapted for direct pluggable connection to the accessory when the latter mounted on the front side of the box.

18. A combination as claimed in any of claims I to 17 in pre-assembled form with said electrical connections already made from the rear of the mounting box to the accessory by the above or other means.

19. A combination as claimed in any of claims 1 to 18 wherein the accessory can, when secured with the mounting box in said aperture as a unit, be removed from the mounting box, leaving the mounting box secured in said aperture.

20. A combination as claimed in claim 19 wherein the accessory includes a face plate spanning the front of the mounting box when assembled into said unit; and wherein apertures are provided in the face plate for securing the accessory to the mounting box with screws.

21. A combination as claimed in claim 20 wherein an additional ,... 4k,.. f..,...,. ..sI.-.+,, ...-4... 4k... ..,.4. ...4.... (......-.. 4k IUI. I. JS 1V IlJ III U I lU. iJu avvoo iv U i a.auatuu *uuuui ui front side of the unit.

22. A method of assembling a unit comprising an electrical wiring accessory and a mounting box of the combination as claimed in any of claims 1 to 21, the method being performed such that electrical connection to the accessory can be made without disassembly of the unit, the actuator for the clamping part is accessible without disassembly of the unit, and the unit is not mounted on any panel.

23. A method of installing an electrical accessory comprising the steps of: providing a combination of wiring accessory and mounting box as claimed in any of claims 1 to 21 assembled in a unit; fitting the unit into a waIl panel aperture by operation of the actuator to clamp the unit to the wall; and making electrical connection between the accessory and supply wiring behind the panel, all of said steps being performed without disassembly of the unit.

24. A mounting box for an electrical wiring accessory, the mounting box being adapted for fitting through an aperture in a panel and having an open front side for receiving the accessory and access for electrical connections toward a rear side thereof, the mounting box being further provided with at least one retractable clamping part and an actuator operable to deploy the retractable clamping part to apply pressure against the rear of the panel to secure the mounting box in pace, said actuator being accessible and readily operable from the rear of the mounting box with said accessory already in place, so as to permit the box and accessory to be pre-assembled off-site and secured in said aperture as a unit.

25. A mounting box for an electrical accessory, substantially as described herein with reference to Figures 1 to 5 or Figures 6 to 10 of the accompanying drawings.