GB2588670A

GB2588670A - Electrical back box

Info

Publication number: GB2588670A
Application number: GB1915920.1A
Authority: GB
Inventors: Brigstocke Nicholas; Dobson Adrian; Robertson David; Muldoon Steven
Original assignee: Fire And Sound Solutions Group Ltd
Current assignee: Fire And Sound Solutions Group Ltd
Priority date: 2019-11-01
Filing date: 2019-11-01
Publication date: 2021-05-05
Also published as: GB201915920D0

Abstract

An insulating insert 200 for an electrical component is three-dimensional and is formed of an injection-mouldable intumescent material. An electrical back box 10 comprises an outer casing 100 and the insulating insert 200, wherein the outer casing is configured to receive the insulating insert 200. The insulating insert 200 may be resiliently deformable and may comprise protrusions for locating it within a metal outer casing 100 and apertures for cables to pass through.

Description

Electrical Back Box [0001] The present invention relates to an insert for an electrical component, and in particular an insulating insert for an electrical back box.

[0002] Electrical components often require insulation, to meet safety requirements. An example of such an electrical component is an electrical socket back box. Conventional electrical socket back boxes comprise a single layer box formed of metal or plastic. In use, the back box is inserted into a wall, and the front cover of the socket is fixed to the back box.

[0003] In order to meet building regulations in respect of acoustic and fire ratings when an electrical back box is used in a dry lined or internal party wall, it is necessary to provide insulation around the back box. This may be provided by pressing and adhering a layer of an insulating material onto the insides of the back box by hand, after the back box has been inserted into the wall; however, this can be a difficult and time-consuming process.

Alternatively, insulating material may be attached to a rear of the wall lining board, over the protruding rear surface of the back box; however, when the wall has been constructed, it is not possible to access the rear of the wall to determine that the insulation is in place.

[0004] According to the present invention there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

[0005] According to a first aspect of the invention, there is provided an insulating insert for an electrical component, wherein the insulating insert is three-dimensional and is formed of an injection-mouldable intumescent material.

[0006] The insert may be a thermally insulating insert. The insert may be configured to expand when it is heated, for example in a fire. The insert may be configured to expand when it reaches a threshold temperature. The insert may be configured to expand in a foaming expansion, forming a foamed body when expanded. The insert may be configured to expand to several times its original volume, for example up to approximately 15 times its original volume. The expansion of the insert may provide an air-tight seal in the electrical component.

[0007] The insert may be resiliently deformable. The insert may be removable from the electrical component. The insert may be configured to be biased against a portion of the electrical component, for example a wall of the electrical component, which may retain the insert in position. The insert being resiliently deformable may thereby help to retain the insert in the electrical component, for example in an air-tight fit.

[0008] The insert may be a unitary insert formed by injection moulding. This may simplify manufacture of the insert, and assembly of the insert within the electrical component.

[0009] The insert may be a free-standing insert. This may provide the advantage that in use, the insert may be easily inserted into the electrical component, without requiring further assembly.

[0010] The injection-mouldable intumescent material may be a halogen-free material. This may reduce the release of toxic fumes from the insert when the insert is heated.

[0011] The insert may be acoustically insulating.

[0012] The insert may be of a shape for fitting into an electrical component, for example an electrical back box. The insert may comprise a base and a plurality of side walls, defining an interior volume.

[0013] The insert may comprise at least one fixing point, for receiving and securing a socket or switch fascia in position. The fixing point may comprise a hole for receiving a fixing, for example, the hole may be a threaded hole for receiving a screw. The insert may comprise a plurality of fixing points.

[0014] The insert may be configured to receive a cover. The insert may comprise an inner lip for receiving the cover. The inner lip may extend around a front edge of the insert. The cover may be configured to at least partially cover the interior of the insert. The cover may be part of an electrical back box and the cover may be receivable on the insert to protect the interior of the back box, for example during plastering, when plaster is applied to the wall surrounding the back box. The cover may be a disposable cover, and may be formed of cardboard.

[0015] The insert may comprise means for positioning the insert within the electrical component. The means for retaining the insert in position may be at least one projection that may project through an opening in the electrical component. For example, the insert may comprise a projection that projects from a rear surface of the insert through an opening in the electrical component. The insert may comprise a plurality of projections for retaining the insert in position within the electrical component.

[0016] The insert may comprise an opening for receiving one or more cables. The insert may comprise a protrusion that may project from a surface of the insert, for example from the rear surface of the insert. The opening may be provided on the protrusion of the insert. The opening may be in the form of a slot. The protrusion may comprise a plurality of openings. The protrusion may be configured to grip a cable in the slot. Providing the protrusion as part of the resiliently deformable insert may allow the protrusion to grip the cables. The protrusion may be configured to expand upon the insert reaching a temperature above a threshold temperature, thereby providing an air-tight seal around the cables.

[0017] According to another aspect of the invention, there is provided an electrical back box comprising an outer casing and an insulating insert, wherein the outer casing is configured to receive the insulating insert and the insulating insert is formed of injection mouldable intumescent material.

[0018] The insert may include any of the features described above in relation to the first aspect of the invention.

[0019] The outer casing may be formed of metal, preferably stainless steel. Forming the outer casing of stainless steel may allow the thickness of the casing to be reduced in comparison to conventional electrical back box casings. In addition, the use of stainless steel may provide an outer casing that is resistant to corrosion and is inert, to reduce the amount of harmful gases emitted when the electrical back box is in contact with a fire or other high temperatures.

[0020] The outer casing may comprise an outer lip. The outer lip may extend outwards from a front edge of the metal casing. The outer lip may be planar and may be configured to abut against a surface of a wall in use, thereby helping to retain the outer case in position. The insert may comprise a corresponding outer lip. The outer lip of the insert may be configured to sit in front of the outer lip of the outer casing when the insert is provided in the outer casing. In the event of the insert being heated over a threshold temperature, the outer lip may expand, thereby providing an air-tight between the electrical back box and a socket or switch fascia that may be attached to the electrical back box when installed. The outer casing being formed of stainless steel may allow the thickness of the outer lip of the outer casing to be reduced, such that the protrusion of the front of the back box from the front surface of a wall may be reduced. This may allow the outer lips to be plastered or skimmed over smoothly.

[0021] The outer casing may comprise a hole for allowing electrical cables to pass through from outside the electrical back box to the interior of the back box. The hole may be provided in a position on the outer casing corresponding to the position of the protrusion on the insert. The protrusion of the insert may project through the hole in the outer casing.

[0022] The outer casing may comprise one or more openings for receiving the means for positioning the insert within the electrical component. The one or more openings may be provided in a rear wall of the back box.

[0023] The electrical back box may comprise an attachment means for attaching the back box in a wall. The attachment means may be a push-out fixing provided in the outer casing. The outer casing may comprise a plurality of push-out fixings. The at least one push-out fixing may be in the form of a wing, with an edge that is configured to abut a rear surface of a board forming a wall. A front surface of the board may be contacted by the outer lip of the metal casing, such that the board is held in place between the outer lip and the push-out fixing. The outer casing may be formed of stainless steel, and the push-out fixings may thereby be flexible, such that a user can easily push out the fixings to fix the back box in place in a wall.

[0024] The outer casing may comprise a plurality of push-out fixings, wherein two or more push-out fixings are provided in different positions in a depth direction of the outer casing.

Different push-out fixings may be pushed out in use according to a thickness of the boards forming the wall. The outer casing may thereby be adapted to be used in walls having different thicknesses of boards.

[0025] The cover and/or insert may comprise a visual indicator, to indicate to a user that the back box complies with specific requirements, for example fire regulations. The visual indicator may be text and/or a symbol, for example a product logo. The text and/or symbol may be printed on the cover. The text and/or a symbol may be provided on the insert, for example injection moulded o the insert.

[0026] According to another aspect of the invention, there is provided a method of manufacturing an insulating insert for an electrical component, comprising forming the insulating insert of intumescent material by injection moulding.

[0027] According to another aspect of the invention, there is provided a method of manufacturing an electrical back box comprising generating an outer casing, forming an insulating insert of intumescent material by injection moulding and inserting the insert into the metal casing.

[0028] Generating the outer casing may comprise cutting a casing portion from a sheet of metal, and bending portions of the casing portion to form the casing.

[0029] Generating the outer casing may comprise cutting one or more push-out fixings in one or more wall portions of the casing cut-out.

[0030] According to another aspect of the invention, there is provided an electrical back box comprising a casing formed of stainless steel, wherein the casing comprises at least one push out fixing.

[0031] Although a few preferred embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.

[0032] For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example only, to the accompanying diagrammatic drawings in which: [0033] Figure 1 shows an exploded view of an example electrical back box; [0034] Figure 2 shows a side view of the electrical back box; [0035] Figure 3 shows a perspective view of the electrical back box; [0036] Figure 4 shows a front view of the electrical back box; [0037] Figure 5 shows a side view of the electrical back box; [0038] Figure 6 shows a perspective view of another example electrical back box; and [0039] Figure 7 shows an exploded view of the electrical back box of figure 6.

[0040] An example electrical component having a thermally and acoustically insulating insert is shown in figures 1-5. The electrical component is an electrical back box 10 comprises an outer casing 100 and an insert 200. The electrical back box 10 may also comprise an optional front cover 300. As shown in figures 1-5, the back box 10 has a rectangular shape, for a double socket. However, in other examples, the back box may take other shapes. For example, the back box may have a square shape for a single socket, as shown in figures 6 and 7.

[0041] The outer casing 100 is formed of stainless steel and comprises a rear wall 102 and side walls 104, 106. The front face of the outer casing 100 is open, and is configured to receive the insert 200 [0042] The insert 200 is formed of an intumescent material and is configured to fit within the outer casing 100. The insert comprises a rear wall 202 and side walls 204, 206. The insert has an open front face, for receiving electrical components, such as wires, within the back box 10. If the insert 200 is heated to a threshold temperature, for example in the event of a fire, the insert is configured to expand, thereby sealing the back box in an air-tight configuration and preventing emissions from escaping from behind the back box and into a room. In addition, the insert acts to provide heat insulation. The insert may be configured to expand in a foaming expansion. The threshold temperature may be greater than 150°C, for example 175°C [0043] The insert 200 is an injection-moulded insert that is moulded in the form of a casing having a base and side walls, the insert being free-standing. The insert can therefore be simply inserted into the outer casing 100, without requiring further assembly of the insert. This provides an advantage over examples of insulating inserts in which a cross-shaped sheet of an insulating material is folded to cover the rear face and side walls of a metal casing, and a further inner casing is provided to hold the sheet in place. An example intumescent material for the insert is a halogen-free intumescent material based on exfoliated graphite.

[0044] The insert 200 is flexible, so that it may be easily inserted in the outer casing. The insert is resiliently deformable and the width of the walls are slightly larger than the interior width of the walls of the casing, such that when the insert is inserted into casing, at least one wall of the insert is deformed and is biased against a corresponding wall of the metal casing. This may securely retain the insert in the metal casing. The insert may thereby be retained in the metal casing in an air-tight fit.

[0045] The outer casing comprises a hole 108 in the rear wall 102. A protrusion 208 is provided in a corresponding position on the rear face 202 of the insert 200. The protrusion 208 is configured to project through the hole 108, as shown in figure 2. The protrusion 208 comprises slots (not shown) through which wires or cables can be inserted. The protrusion 208 is resiliently deformable, and acts to clasp the cables within the slots. The protrusion may expand upon reaching a threshold temperature, and thereby may provide an air-tight seal around the cables.

[0046] The outer casing 100 also comprises at least one opening 110 in the rear face. The insert 200 comprises one or more of projections 212 that project from a rear face of the insert and are configured to project through the locating openings 110 of the rear face. The projections 212 can aid in retaining the insert 200 in a desired position within the outer casing 100.

[0047] The insert 200 comprises an interior lip 214 provided around a front edge of the insert 200, as shown in figure 1. The interior lip 214 extends around the inner perimeter of the insert 200. The interior lip 214 is configured to receive the front cover 300. When the front cover 300 is inserted on the electrical back box 10, the edges of the front cover 300 are arranged to sit on the lip 214.

[0048] The optional front cover 300 is a rectangular cover that fits on a front of the insert 200, on the interior lip 214. The front cover may be formed of cardboard or other man-made material. The front cover 300 is removable and may be used during plastering, to protect the interior of the back box. After plastering, the front cover may be removed, and a socket front may be attached to the back box by connecting wires and fixing the socket front to the insert using mechanical fixings, for example screws. The front cover 300 comprises a fold-out portion 302 that projects from a front surface of the front cover and that can be gripped by a user when inserting or removing the front cover 300 from the back box.

[0049] The outer casing comprises an outer lip 112 that projects outwards from the front edge of the outer casing 100. The outer lip 112 may help to hold the back box 10 in the position in the wall. As shown in figures 1 and 5, an outer lip 112 projects outwards from the front edge of each of the side-walls 104, 106. In other examples, the outer lip may be continuous around the front edge of the outer casing. The insert 200 may comprise a corresponding outer lip 216 that sits on the outer lip 112 of the outer casing as shown in figures 1, 2 and 5. The outer lip 216 of the insert is configured to provide an air-tight seal between the electrical back box and a socket fascia attached to the back box in use.

[0050] The outer casing 100 being formed of stainless steel allows the thickness of the outer lip 112 of the casing 100 to be minimised, thereby reducing the overall thickness of the portion of the back box 10 that projects from the surface of the wall. For example, the thickness of the outer lip 112 of the metal casing 100 and the outer lip 216 of the insert 200 together may be approximately 1-2 mm, which may be an approximate thickness of plaster that is skimmed over the plaster board. This may allow the outer lip to be approximately flush with the surface of the wall.

[0051] The insert comprises two fixing points, for attaching a socket or switch fascia to the electrical back box. Each fixing point comprises an opening for receiving a fixing, such as a screw. The openings are elongate, so that the position of the socket or switch fascia may be adjusted during attachment.

[0052] The outer casing 100 comprises a plurality of push-out wings 118 provided on two of the side-walls of the outer casing. The push-out wings 118 are configured to retain the outer casing in position in a dry lined or party wall. The use of push-out wings provides the advantages that the back box may be easily secured to a wall and the outer casing may be simple and low-cost to manufacture.

[0053] The push-out wings 118 are substantially triangular in shape, with each wing comprising a front edge 120 that is substantially parallel to a front edge 122 of the outer casing, as shown in figure 2. A side edge 124 of each wing 118 is connected to the side wall 106 of the outer casing. A rear edge 126 of the wing extends from the front edge towards a distal end of the side edge 124.

B

[0054] In use, the outer casing 100 may be inserted into an opening in a wall, and the push-out wings 118 may be pushed outwards from the interior of the casing to project from the wall of the outer casing, by folding the wing 118 along the side edge 124. The front edge 120 of the wing 118 may be substantially parallel to the plane of a wall and that is configured to abut against the edge of a wall. In use, the wall is held between the wing 118 and the outer lip 112 of the outer casing 100. In other examples, push-out wings 118 may be provided on only one side wall 104, 106, or may be provided on more than two side walls 104, 106.

[0055] As shown in figure 2, a first pair of wings 118a is provided in a first position, wherein the front edge 120 of the wing 118 is provided at a first distance dl from a rear surface of the outer lip 112. A second pair of wings 118b is provided in a second position, wherein the front edge 120 of the wing is provided at a second distance d2, different to the first distance dl, from the rear surface of the outer lip 112. In use, either the first pair of wings 118a or the second pair of wings 118b may be pushed out to secure the back box 10 to the wall, depending on the thickness of the plaster board. The thickness of the plasterboard may be set according to a fire rating. For example, the distance dl may be approximately 19 mm, which may be the thickness of two standard 9.5 mm plasterboard sheets, which may be a requirement for a fire-rated wall. In another example, the distance dl may be approximately 12.5 mm, to accommodate a 12.5 mm plasterboard sheet. The distance d2 may be approximately 25 mm to accommodate two thicker, 12.5 mm plasterboard sheets.

[0056] In other examples, the back box may be surface-mounted to a wall, rather than inserted in an opening in a wall. In these examples, the back box may not include the push-out wings.

[0057] A method of manufacturing the electrical back box 10 will now be described. The outer casing 100 is generated by cutting a shape out of a stainless steel sheet and bending at edges so that the walls 104, 106 of the casing are perpendicular to a rear surface 102. The edges of the walls are then connected to form the box-shape of the casing.

[0058] The cutting the shape from the stainless steel sheet comprises cutting a plurality of holes 108, 110 in the rear face portion of the sheet, to form the openings for receiving the protrusion 208 and projections 212 of the insert. The cutting the shape also comprises cutting a plurality of wings 118 in one or more side wall portions of the sheet, to form the push-out fixings.

[0059] The insert is generated by injection moulding an intumescent material to form a box-shaped insert, including a protrusion 208 and plurality of projections 212 for extending through the holes 108, 110 in the rear face of the outer casing.

[0060] In use, the outer casing may be inserted into an opening in a dry lined wall, and the push-out wings are pushed out to hold the outer casing in place. Cables pass through the central hole 108 of the box, from the rear of the box into the interior of the box. The cables are then pulled through the slots in the protruding portion of the insert, and the insert is fitted into the outer casing. The front cover is inserted onto the front of the insert, seated on the lip, and the wall can then be plastered around the back box. The front cover may then be removed and a socket fascia secured to the back box. The back box may be retro-fitted to existing walls. The back box may eliminate a problem in refurbishment and fire upgrades in that the insulating material in existing back boxes are discarded and not reinstated.

[0061] An example electrical back box 1010 may be a back box for a single socket, as shown in figures 6 and 7. The single-socket electrical back box 1010 comprises an outer casing 1100, an insert 1200 and an optional front cover 1300, which respectively correspond to the outer casing 100, insert 200 and front cover 300 of the electrical back box 10 shown in figures 1-5 and include corresponding features. The cover portion 1300 comprises a fold-out portion 1302 that projects from a front surface of the front cover. The outer casing 1100 is formed of stainless steel and comprises a rear wall 1102 and side walls 1104, 1106 and comprises an outer lip 1112 that projects outwards from the front edge of the outer casing 1100 and a plurality of push-out wings 1118 provided on two of the side-walls of the outer casing 1100. The insert 1200 is formed of an intumescent material and is configured to fit within the outer casing 1100. The insert comprises a rear wall 1202 and side walls 1204, 1206, an interior lip 1214, and an outer lip 1216 that sits on the outer lip 1112 of the outer casing. The outer casing comprises a hole (not shown) in the rear wall 1102. A protrusion (not shown) is provided in a corresponding position on the rear face 1202 of the insert 1200.

[0062] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0063] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[0064] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0065] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. An insulating insert for an electrical component, wherein the insulating insert is three-dimensional and is formed of an injection-mouldable intumescent material.
2 The insulating insert according to claim 1, wherein the insert is resiliently deformable.
3. The insulating insert according to claim 1 or claim 2, wherein the insert is a unitary insert and is free-standing.
4. The insulating insert according to any preceding claim, wherein the electrical component comprises an outer casing, and the insulating insert comprises means for positioning the insert within the outer casing.
5. The insulating insert according to any preceding claim, wherein the insert comprises a rear surface and side walls defining an interior of the insert, and wherein the insert is configured to receive a cover for at least partially covering the interior of the insert.
6. The insulating insert according to any preceding claim, wherein the insert comprises an opening for receiving electrical cables, wherein the opening is one or more slots provided on a projection of the insert, wherein the projection is configured to grip the cables within the one or more slots.
7. An electrical back box comprising an outer casing and the insulating insert according to any preceding claim, wherein the outer casing is configured to receive the insulating insert.
8. The electrical back box according to claim 7, wherein the outer casing is formed of stainless steel.
9. The electrical back box according to claim 7 or claim 8, wherein the outer casing comprises one or more openings to receive corresponding projections of the insert, for positioning the insert within the outer casing.
10. The electrical back box according to any of claims 7 to 9, wherein the electrical back box comprises an attachment means for attaching the back box in a wall, wherein the attachment means comprises at least one push-out fixing provided in the outer casing.
11. The electrical back box according to claim 10, wherein the attachment means comprises a plurality of push-out fixings, wherein two or more push-out fixings are provided in different positions in a depth direction of the outer casing.
12. The electrical back box according to any of claims 7 to 11, wherein the outer casing comprises an outer lip for contacting a surface of a wall, and the insert comprises a corresponding outer lip, wherein the outer lip of the insert is configured to expand when heated above a threshold temperature.
13. A method of manufacturing an insulating insert for an electrical component, comprising forming the insulating insert of intumescent material by injection moulding.
14. The method according to claim 13, wherein forming the insulating insert comprises forming a plurality of projections, projecting from a rear wall of the insert, for positioning the insert within the electrical component.
15. The method according to claim 13 or claim 14, wherein forming the insulating insert comprising forming a protrusion having at least one slot for receiving and gripping a cable.