Apparatus

Abstract

An electrical device assembly 2, comprising a back box 10 configured to receive a power cable of an electrical power supply and a face plate 12 mountable on the back box and comprising an electrical d

Description

FIELD The present invention relates to a system and apparatus for electrical fittings. BACKGROUND The design and installation of electrical fittings such as plug sockets and light switches is well known. Most electrical fittings comprise a back box that is fitted to a surface, such as a wall, or recessed in such a surface, and a separate face place that is mounted on the back box. Electrical power supply cables are routed to enter / exit the back box, through apertures in the walls thereof, and are coupled to terminals in the face plate that is mounted on the back box to provide electrical power to the face plate. The face plate typically has an electronic device on its front face. There are a number of possible electrical devices such as switches, dimmer switches, plug sockets, temperature dials, and the like. The current designs and installation methods means that the front face (i.e. the face plate) is wired directly to the electrical power supply cables of an electrical power circuit (sometimes called a ring main). Mounting a face plate to a newly installed back box, or as a replacement face plate for an existing back box can be a difficult and time-consuming process as the ring main wires must be cut to specific lengths, stripped, and fitted to the face plate by screw terminals. The ring main is often concealed within walls in which the back box is recessed, or mounted thereon and, in order to proceeding with such cutting and stripping of the wires, the installer usually has to pull these wires from within the walls and through the back box so that they have a sufficient length of cable to provide space to work when fitting the wires to the front plate. Once connected to the ring main wires, the excess cable length has to be pushed back into the wall so that the face plate can be fixed / mounted to the back box. Often, this can lead to the individual ring main wires being pulled out of the terminal on the front face. Moreover, when reinstalling the face plate, stress is put on the terminal connection point, to which the ring main wires are connected, which may lead to the ring main wires becoming loose and / or damaged. If these faults are undetected, the loose / damaged wires could become a fire hazard, or electrocution hazard. Aspects and embodiments of the invention have been devised with the foregoing in mind. SUMMARY According to an aspect of the invention there is provided an electrical device assembly comprising a back box configured to receive a portion of a power cable of an electrical power supply; a face plate mountable on the back box and comprising an electrical device; wherein the back box comprises a power supply coupling, wherein the power supply coupling comprises a plurality of terminals configured to connect to the electrical power supply and a first plurality of electrical coupling elements, the power supply coupling further comprising a plurality of conductive paths between the plurality of terminals and respective ones of the first plurality of electrical coupling elements; and further wherein the face plate comprises a second plurality of electrical coupling elements for electrically coupling the face plate to corresponding complementary ones of the first plurality of electrical coupling elements, the face plate further comprising a plurality of conductive paths between the respective ones of the second plurality of electrical coupling elements and corresponding terminals of the electrical device such that, when mounted on the back box there is an electrical connection between the power supply coupling in the back box and the electrical device on the face plate. Optionally, the first plurality of electrical coupling elements and the second plurality of electrical coupling elements comprise complementary electro-mechanical couplings. This provides not only an electrical coupling between the back box and the face plate but an additional mechanical coupling. Such a mechanical coupling may provide additional mechanical strength to hold the face plate on the back box while the user secures face plate with a more permanent fitting, such as screws or the like. Moreover, male and female configurations allow the face plate to be easily removed from the back box. Optionally, the first plurality of electrical coupling elements and the second plurality of electrical coupling elements comprise complementary push fit couplings. Push fit couplings can be easily pushed to fit together to save time, can be easily removed, and are simple to use. Optionally, the first plurality of electrical coupling elements comprises a pin and the second plurality of electrical coupling elements comprises a female coupling element arranged to receive the pin to form a complementary engagement therebetween. The female pin located in the back box provides the advantage that when the external electrical power supply is coupled to the respective email coupling element, a user cannot be electrocuted, thus increasing safety. A pin and complimentary female coupling element also advantageously provides a strong electro-mechanical coupling between the face plate and the back box. Optionally, the first plurality of electrical coupling elements comprise two pins and the second plurality of electrical coupling elements comprise two female coupling elements arranged to receive the corresponding pins of the first plurality of electrical elements to form a complementary engagement therebetween. A two pin and two female coupling element arrangement provides the advantage that the live and neutral wires can be fixed directly to these elements. Thus, simplifying the construction as well as providing an additional electromechanical coupling element between the face plate and box. This increases the mechanical holding strength between the face plate and the back box. Optionally, the first plurality of electrical coupling elements comprises three pins and the second plurality of electrical coupling elements comprises three female coupling elements arranged to receive the corresponding pins of the first plurality of electrical elements to form a complementary engagement therebetween. An additional third pin provides the advantage of increased mechanical strength. Optionally, the first plurality of electrical coupling elements comprises a female coupling element and the second plurality of electrical coupling elements comprises a pin, the female coupling element arranged to receive the pin to form a complementary engagement therebetween. Optionally, the first plurality of electrical coupling elements comprises two female coupling elements and the second plurality of electrical coupling elements comprises two pins, the female coupling elements arranged to receive the corresponding pins to form a complementary engagement therebetween. Optionally, the first plurality of electrical coupling elements comprises three female coupling elements and the second plurality of electrical coupling elements comprises three pins, the female coupling elements arranged to receive the corresponding pins of the first plurality of electrical elements to form a complementary engagement therebetween. Optionally, the electrical coupling between the second plurality of electrical coupling elements in the face plate and corresponding complementary ones of the first plurality of electrical coupling elements in the back box comprises a touch contact coupling. A touch contact coupling requires less force when fitting the plates to the back box. Moreover this simplifies construction. Optionally, the electric device on the face plate comprises a plug socket configured to receive an electrical plug. Optionally, the electric device on the face plate comprises a light switch. According to a second aspect of the invention there is provided a back box for an apparatus according to first aspect, comprising: a power supply coupling, wherein the power supply coupling comprises a plurality of terminals configured to connect to an electrical power supply and a plurality of electrical coupling elements, the power supply coupling further comprising a plurality of conductive paths between the plurality of terminals and respective ones of the plurality of electrical coupling elements. According to a third aspect of the invention there is provided a face plate for an apparatus according to the first aspect, comprising: an electrical device; a plurality of electrical coupling elements for electrically coupling the face plate to corresponding complementary ones of a plurality of electrical coupling elements of a back box, to which the face plate is mountable, the face plate further comprising conductive paths between the respective ones of the plurality of electrical coupling elements and corresponding terminals of the electrical device such that, when mounted on a back box there is an electrical connection between the power supply coupling in the back box and the electrical device on the face plate. According to a fourth aspect of the invention there is provided a power supply coupling for location in a back box of an electrical device, wherein the power supply coupling comprises a plurality of terminals configured to connect to an electrical power supply and a plurality of electrical coupling elements, the power supply coupling further comprising a plurality of conductive paths between the plurality of terminals and respective ones of the plurality of electrical coupling elements. Optionally, the power supply coupling, when located in a back box, is configured to be used with a face plate according to third aspect of the invention. With such a power supply coupling, existing back boxes that are already mounted to a surface can be upgraded to be compatible with the face plates according to the third aspect of the invention. According to a fifth aspect of the invention there is provided a kit of parts comprising the face plate according to the third aspect of the invention and a power supply coupling according to the fourth aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS One or more specific embodiments in accordance with aspects of the present invention will be described, by way of example only, and with reference to the following drawings in which: Fig. 1 illustrates a schematic diagram of an electrical fitting according to one or more embodiments of the present invention; Fig. 2A illustrates a schematic diagram of a back box of an electrical fitting according to one or more embodiments of the present invention; Fig. 2B illustrates a schematic circuit diagram of a back box of an electrical fitting according to one or more embodiments of the present invention; Fig. 3 illustrates a schematic diagram of a face plate of an electrical fitting according to one or more embodiments of the present invention; Fig. 4A illustrates a schematic diagram of a retro-fit component according to one or more embodiments of the present invention; and Fig. 4B illustrates a schematic diagram of a retro-fit component mounted in a back box according to one or more embodiments of the present invention. DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS The invention relates to improvements to existing electrical fittings and will be described in relation to Fig. 1, which is a simplified schematic illustration of an electrical fitting 2 when viewed from a side angle in accordance with one or more embodiments of the invention. It should be noted that Fig. 1 is not to scale and may comprise further components than the ones described herein. The electrical fitting 2 comprises a back box 10 and a removable front plate 12 (sometimes referred to as a face plate), which can be attached to the back box 10 by means of screws, clips, or other fasteners (not shown in this figure). Typically, the back box 10 is fixed onto a surface of a wall, or recessed in a cavity in a wall (fixings not shown in this figure). The back box 10 comprises various apertures to permit electrical power supply cable to be fed through them. Such power supply cables, when operating under a three-phase power supply, comprise a first cable, or wire, referred to as “live”, and a second cable, or wire, referred to as “neutral”. Often, a third cable, or wire, may be present to provide a ground / earth. The currently described one or more embodiments comprise “live”, “neutral” and “earth” wires. It should be appreciated that most common back boxes require the user to cut their own apertures as desired so as to accommodate different cable arrangements and entry / exit points. The back box 10 further comprises three electrical coupling elements 14, 16, and 18. In this embodiment, the electrical coupling elements 14, 16, and 18 are female coupling elements to which the electrical power supply cables are wired, either via screw terminals (not shown in this figure) or snap fit terminals (not shown in this figure). That is, the individual live, neutral, and earth wires of the electrical power supply cables are connected to respective ones of the three electrical coupling elements 14, 16, and 18. The face plate 12 comprises three electrical coupling elements 20, 22, and 24, which are electrically connected to an electrical device (now shown in this figure) that is present on the face plate 12. In this embodiment, the three electrical coupling elements 20, 22, and 24 are male fittings, such as a pin as referred to herein, and are each configured to engage with a corresponding one of the electrical coupling elements 14, 16, and 18 when the face plate 12 is mounted onto the back box 10. In this embodiment, the pin 20 is configured to engage in a complementary way with the female coupling element 14 to form an electrical connection between the front face 12 and the electrical power supply wire connected to the female coupling element 14. The pin 22 is configured to engage with the female electrical coupling element 16 to form an electrical connection between the front face 12 and the ring main electrical power supply wire connected to the female coupling element 16. The pin 24 is configured to engage with the female coupling element 18 in the same manner, to form an electrical connection between the front face 12 and the ring main electrical power supply wire connected to the female coupling element 18. Since the female electrical coupling elements 14, 16, and 18 are connected to the individual wires of the ring main, when the front face 12 is mounted to the back box 10, the pins 20, 22, and 24 likewise are electrically connected to these wires. Therefore, any device in the front plate 12, such as a plug socket or light switch, will be connected to the electrical power supply via this complementary coupling arrangement. While not strictly necessary to achieve electrical connection, the complimentary coupling between the pins 20, 22 and 24 and the female coupling elements 14, 16 and 18 also provides a mechanical connection between the front face 12 and the back box 10. However, it should be appreciated that this is an optional addition to the primary function of providing an electrical connection between the front face 12 and the back box 10. The back box 10 will now be described in more detail with reference to Figs. 2A and 2B. Fig. 2A is a schematic diagram showing the back box 10 when viewed from above in accordance with an embodiment of the invention. As described in relation to Fig. 1, the back box 10 comprises the three female electrical coupling elements 14, 16, and 18. Fig. 2a shows how an electrical power supply cable 28 is connected to the back box 10. As can be seen, the electrical power supply cable 28 comprises three separate individual wires numbered 30, 32, and 34, which connect to terminals 36, 38, and 40 respectively. The terminals 36, 38, and 40 could be screw fittings that are commonly known in the art, or other fittings that permit the individual ring main wires to be fixed in a secure way and form an electrical connection between them and the respective wires. In this embodiment, there are additional terminals 42, 44, and 46, which connect to wires 48, 50, and 52 respectively of a second electrical power supply cable 29. In such an arrangement, i.e., one with two electrical power supply cables entering / exiting the back box 10, the electrical fitting 2 is part of a so-called “ring main”. As will be appreciated, if the back box is located at the end of an electrical “spur” from the “ring main”, then only one electrical power supply cable would enter the back box and only one set of three terminals would be required in the back box. Fig. 2B is a schematic illustrative diagram showing the back box 10 from above and including an illustrative schematic circuit diagram. The circuit diagram shows how the previously mentioned terminals 36, 38, 48, 42, 44, and 46 are connected to the female coupling elements 14, 16, and 18. As described above with reference to Fig. 2A, there are three ring main wires connected to the electrical terminals 36, 38, and 40 and three other ring main wires that connect to the electrical terminals 42, 44, and 46. Two neutral ring main wires 34, and 52 are connected to electrical terminals 40 and 46 respectively. These terminals are electrically connected to the female coupling element 14 by way of an electrical path 52, which is indicated by the dotted lines. Similarly, live ring main wires 30 and 48 are connected to electrical terminals 36 and 42 respectively. These are in turn connected to the female coupling element 16 by way of an electrical path 54, which is indicated in solid lines. Finally, two earth ring main wires 32 and 50 are connected to the electrical terminals 38 and 44 respectively. These are connected to female coupling element 18 by electrical path 56, which is indicated by the dashed lines. The female coupling element 18 may, in some arrangements, be electrically coupled to the back box 10 so as to provide earthing via the back box 10. This is in accordance with “best practice” in the UK. The face plate 12 will now be described in more detail with reference to Fig. 3, which is a schematic illustration of a double UK three pin plug (Type G). Please note that this is not to scale, and other components and / or fittings may not be described herein. Fig. 3, shows the face plate 12 from a back side, i.e., a side that would face the back box 10 when mounted to the back box. In addition to the components described above in relation to Fig. 1, the face plate 12 comprises a first electrical device 62 and a second electrical device 64, both of which are indicated with the dash-dot lines. The first electrical device 62 and the second electrical device 64 both comprise three apertures to receive a complimentary three pin plug: earth apertures 66 and 68, neutral apertures 70 and 72 and live apertures 74 and 76 respectively. The apertures for receiving an earth pin of an electric plug will be referred to hereinafter as earth apertures 66 and 68. Earth apertures 66, 68 contain respective electrical couplings that are electrically connected to the pin 20 by electrical path 78. The apertures for receiving a neutral pin of an electric plug will be referred to hereinafter as neutral apertures 70 and 72. Neutral apertures 70, 72 contain respective electrical couplings that are electrically connected to the pin 24 by electrical path 80. The apertures for receiving a live pin of an electric plug will be referred to hereinafter as live apertures 74 and 76. Live apertures 74, 76 contain respective electrical couplings that are electrically connected to the pin 22 by electrical path 82. When the front face 12 is mounted on back box 10, the pins 20, 22, and 24 engage with female coupling elements 14, 16, and 18. Electrical connections are formed between the respective electrical couplings located in the apertures of electrical devices 64 and 66 with female coupling elements 14, 16, and 18 of the back box 10, via the pins 20, 22, and 24 of the face plate 12. This, in turn means, that the electrical devices 62 and 64 will be electrically connected to the electrical power supply cables via the terminals and previously described electrical paths 52, 54, and 56. The arrangement described above has many advantages over existing solutions where the device on the face plate 12 would normally be wired directly to the ring main wires and the back box merely serving as a mounting point. By wiring the electrical power supply cables to the back box and providing a convenient, electrical coupling system like the one described above, one can simply mount the face plate to the back box to achieve an electrical connection to the electrical power supply. This is a simple procedure meaning that changing a face plate may be relatively straightforward, because one can merely remove the current face plate and replace it with another compatible face plate. Changing the design or look of the face plate may be desirable when remodeling a room in which the electrical fitting 2 is mounted. The system of the present invention may provide a convenient way to replace an existing face plate with a new / replacement one. In addition to the above, the improved system may reduce the length of ring main cable required to be left after the so called “first fix”. The first fix is the preparation stages of wiring a building, where an electrician prepares the skeleton of the building electrical power supply, i.e., the installation of power supply cables. This usually occurs before plastering is done and so most of the wiring will not be visible afterward. Normally, during the first fix, the electrician will mount the back boxes, feed the power supply cable to it, and leave long lengths of excess cable exposed so that, once the plastering is done, they can return to the site and fit the face plates. The new electrical fitting 2 as described above means that during the first fix, the electrician can wire directly and easily to the terminals provided in the back box 10. The excess length of cable that is normally left is not required, and results in much less wastage of electrical cable for new builds or situations when a house is being re-wired. This may provide cost-savings as well as providing environmental benefits, through less wastage. The system of the present invention may also provide time savings during a so-called “second fix”, which is when electricians will fit the face plates to the back boxes after the plastering work has been completed. At the same time, they will normally wire the face plate directly to the electrical power supply cables. As explained above, in one or more embodiments of the present invention the electrical power supply cables are already wired to the back box 10 and so the electrician, on their return to conduct the “second fix”, may need only to mount a compatible face plate 12 to the back box 10 in order to complete the installation. Figs. 1 to 3 above disclose a power supply coupling system which comprises the terminals 36, 38, 40, 42, 44, and 46, and the pins 20, 22, 24. In those figures, the power supply coupling is mounted directly in the back box 10 and can be supplied with the back box 10. Such a system may be appropriate for new installations where either the existing back boxes are being replaced, or where new fittings are being mounted in a new build. However, a person skilled in the art will appreciate that there are many existing electrical fittings comprising back boxes. A power supply coupling suitable for retrofitting in existing back boxes will be described with reference to Figs. 4A and 4B. The features of Figs. 4A and 4B that are the same as Figs. 2A and 2B are indicated with the same reference numerals. Fig. 4A is a schematic illustrative diagram showing a power supply coupling 90 when viewed from above. Fig. 4B is a schematic illustrative diagram showing the power supply coupling 90 mounted in a back box 100 when viewed from above. The back box 100 differs from the back box 10 in that it is already mounted upon or within a surface (not shown in these figures). The power supply coupling 90 comprises a support member 92 which is suitable to be mounted in an existing back box, i.e., back box 100. Such a mounting may be removable or permanent by way of fixings elements such as rivets, screws, tape, or any other fixing (not shown in these figures). The power supply coupling 90 comprises terminals 36, 38, 48, 42, 44, and 46 and female coupling elements 14, 16, and 18 that were previously described in relation to Figs. 2A and 2B. As will be evident from the figures, the conductive paths between respective ones of the plurality of terminals and the corresponding female coupling elements that was described in relation to Fig. 2B is not shown here. However, we refer to Fig. 2B for this information, which is incorporated into this embodiment. In this embodiment, the support member 92 is formed of a rectangular cross with the female coupling elements 14, 16, and 18 situated along one length of the cross and the terminals 36, 38, 48, 42, 44, and 46 to which power supply wires (not shown in this image) mounted on the other length of the cross perpendicular to the length which the female coupling elements are mounted. The support member 92 could be formed of any existing material, such as a plastic material according to safety standards. In use, the power supply coupling 90 and be positioned within a back box and secured therein by way of the fixings described above. Once this has been completed, the external power supply wires may be fixed to the terminals as described above and a compatible face plate, mounted on the back box. The power supply coupling 90 could be supplied as a kit or parts with a compatible face plate (not shown here in these figures) and used to retrofit existing back boxes. An example face plate could be the face plate described with reference to Fig. 3. The power supply coupling 90 provides the advantage that existing back boxes can be retrofitted to include the advantageous effects previously described above in relation to Figs. 1 to 3. This means that a user need not purchase a back box if they wish only to upgrade their existing electrical devices. The electrical coupling elements 14, 16, and 18 on the back box 10 are described as female electrical coupling elements arranged to receive corresponding male coupling elements 20, 22, and 24 in order to complementarily engage to form an electrical connection. However, it should be appreciated that they may easily be swapped for male coupling elements. Of course, in order to form the complementary engagement with the front face, the electrical coupling elements on the front face would likewise have to be swapped from female to male connection elements. In other embodiments, it could be envisaged that the three complementary electrical coupling elements are formed as a single pin with separate electrical connection points. Examples of such connectors is a so called ‘phone connector’ (also known as phonejack, audio jack, headphone jack, stereo jack or jack plug) comprising three coaxial connection points; coaxial cables; or other single pin solutions. The face plate 12 is described above having two three-pin electrical plug sockets (electrical devices 62 and 64). It should be appreciated that other electrical devices could be equally implemented on such a face plates 12. Such devices could be light switches, household appliance switches, safety switches, sensors, or other plug arrangements (two pin for example). Moreover, the term “plug socket” may include other safety switches that were not shown in the figures above, such as switches to isolate the conductive paths 52, 54, or 56. The earth sockets 66 and 68 are relevant to the British style Type G, 3 pin plug sockets. Of course, the pin 20 could equally be in electrical connection with earth contact plates that are used in European countries in the Type G, two pin sockets. This would mean that instead of being an aperture to receive a plug pin, apertures 66 and 68 would be metal plates such as used in European style plugs. Some countries and devices do not require earthing and so, in other embodiments of the present invention, the earth connection between the front face and back plate may be removed entirely. This results in only two complementary electrical connections required for the live and neutral ring main wires.The support member 92 is described above as being a rectangular cross. However, it will be appreciated that any shape may be used in order to provide a support for the one or more coupling elements and terminals. It will be understood by those skilled in the art that the drawings are merely diagrammatic and that further items of equipment may be required in a commercial apparatus. The position of such ancillary items of equipment forms no part of the present invention and is in accordance with conventional practice in the art. As used herein any reference to “one embodiment” or “an embodiment” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. Moreover, one or more features of different embodiments may be combined to create further embodiments not specifically described herein, and any one or more features may be combined consistent with their technical and operational compatibility. To the extent that one or more features from respective embodiments may not be combined without being inconsistent with the technical and / or operational compatibility such features from respective embodiments may be selected for combination which do not have such technical and / or operational compatibility. All such embodiments are contemplated within the scope of this disclosure. As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present). In addition, use of the “a” or “an” are employed to describe elements and components of the invention. This is done merely for convenience and to give a general sense of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise. In view of the foregoing description, it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.

Claims

1. An electrical device assembly, comprising:a back box configured to receive a portion of a power cable of an electrical power supply;a face plate mountable on the back box and comprising an electrical device;wherein the back box comprises a power supply coupling, wherein the power supply coupling comprises a plurality of terminals configured to connect to the electrical power supply and a first plurality of electrical coupling elements, the power supply coupling further comprising a plurality of conductive paths between the plurality of terminals and respective ones of the first plurality of electrical coupling elements; andfurther wherein the face plate comprises a second plurality of electrical coupling elements for electrically coupling the face plate to corresponding complementary ones of the first plurality of electrical coupling elements, the face plate further comprising a plurality of conductive paths between the respective ones of the second plurality of electrical coupling elements and corresponding terminals of the electrical device such that, when mounted on the back box there is an electrical connection between the power supply coupling in the back box and the electrical device on the face plate.

2. An electrical device assembly according to claim 1, wherein the first plurality of electrical coupling elements and the second plurality of electrical coupling elements comprise complementary electro-mechanical couplings.

3. An electrical device assembly according to any preceding claim, wherein the first plurality of electrical coupling elements and the second plurality of electrical coupling elements comprise complementary push fit couplings.

4. An electrical device assembly according to any preceding claim, wherein the first plurality of electrical coupling elements comprises a pin and the second plurality of electrical coupling elements comprises a female coupling element arranged to receive the pin to form a complementary engagement therebetween.

5. An electrical device assembly according to any of claims 1 to 3, wherein the first plurality of electrical coupling elements comprise two pins and the second plurality of electrical coupling elements comprise two female coupling elements arranged to receive the corresponding pins of the first plurality of electrical elements to form a complementary engagement therebetween.

6. An electrical device assembly according to any of claims 1 to 3, wherein the first plurality of electrical coupling elements comprises three pins and the second plurality of electrical coupling elements comprises three female coupling elements arranged to receive the corresponding pins of the first plurality of electrical elements to form a complementary engagement therebetween.

7. An electrical device assembly according to claims 1 to 3, wherein the first plurality of electrical coupling elements comprises a female coupling element and the second plurality of electrical coupling elements comprises a pin, the female coupling element arranged to receive the pin to form a complementary engagement therebetween.

8. An electrical device assembly according to any of claims 1 to 3, wherein the first plurality of electrical coupling elements comprises two female coupling elements and the second plurality of electrical coupling elements comprises two pins, the female coupling elements arranged to receive the corresponding pins to form a complementary engagement therebetween.

9. An electrical device assembly according to any of claims 1 to 3, wherein the first plurality of electrical coupling elements comprises three female coupling elements and the second plurality of electrical coupling elements comprises three pins, the female coupling elements arranged to receive the corresponding pins of the first plurality of electrical elements to form a complementary engagement therebetween.

10. An electrical device assembly according to claim 1, wherein the electrical coupling between the second plurality of electrical coupling elements in the face plate and corresponding complementary ones of the first plurality of electrical coupling elements in the back box comprises a touch contact coupling.

11. An electrical device assembly according to any preceding claim, wherein the electric device on the face plate comprises a plug socket configured to receive an electrical plug.

12. An electrical device assembly according to any preceding claim, wherein the electric device on the face plate comprises a light switch.

13. A back box for an apparatus according to any of claims 1 to 12, comprising:a power supply coupling, wherein the power supply coupling comprises a plurality of terminals configured to connect to an electrical power supply and a plurality of electrical coupling elements, the power supply coupling further comprising a plurality of conductive paths between the plurality of terminals and respective ones of the plurality of electrical coupling elements.

14. A face plate for an apparatus according to any of claims 1 to 12, comprising:an electrical device;a plurality of electrical coupling elements for electrically coupling the face plate to corresponding complementary ones of a plurality of electrical coupling elements of a back box, to which the face plate is mountable, the face plate further comprising conductive paths between the respective ones of the plurality of electrical coupling elements and corresponding terminals of the electrical device such that, when mounted on a back box there is an electrical connection between the power supply coupling in the back box and the electrical device on the face plate.

15. A power supply coupling for location in a back box of an electrical device, wherein the power supply coupling comprises a plurality of terminals configured to connect to an electrical power supply and a plurality of electrical coupling elements, the power supply coupling further comprising a plurality of conductive paths between the plurality of terminals and respective ones of the plurality of electrical coupling elements.

16. A power supply coupling according to claim 15, wherein the power supply coupling, when located in a back box, is configured to be used with a face plate according to claim 14.

17. A kit of parts comprising the face plate according to claim 14 and a power supply coupling according to claims 15 and 16.

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