GB2170660A

GB2170660A - Wall box for an electrical accessory

Info

Publication number: GB2170660A
Application number: GB08502840A
Authority: GB
Inventors: Clifford Ian Upright; Alan Evans
Original assignee: CITY ELECTRICAL FACTORS Ltd
Current assignee: CITY ELECTRICAL FACTORS Ltd
Priority date: 1985-02-05
Filing date: 1985-02-05
Publication date: 1986-08-06
Also published as: GB8502840D0; GB2170660B

Abstract

A wall box includes a peripheral flange (2) sides (3, 4) having apertures (5, 6), and retention devices (11) each of which is movable between a retracted position (Fig. 3) in which a lug (14) thereof lies within the box and an extended position in which the lug extends outwardly through the apertures to each lug being further movable in a direction perpendicular to said housing open end to a position (Fig. 5) in which it cannot be retracted because of interference from the respective box side (3,4). Locking projections (20) are provided in said apertures to hold the devices (11). <IMAGE>

Description

SPECIFICATION Wall box for an electical accessory This invention relates to a wall box for an electrical accessory, such as a switch or socket, useful for mounting such an accessory in a cavity wall or partition.

Modern cavity walls for internal use usually consist of relatively thin spaced wall elements having insufficient substance for the reliable reception of screws or other external fixings means and wall boxes for use in such walls are usually provided with lugs arranged to lie behind the outermost wall element of a cavity wall to assist in retaining the box in position.

An object of the invention is to provide a wall box for an electrical accessory which is provided with improved means for its retention in a cavity wall.

According to the invention, a wall box comprises a hollow housing having one open end with lateral flange means projecting outwardly adjacent said open end, each of two sides of the housing having a respective aperture therethrough, a pair of retention devices each mounted in the housing for sliding movement between a retracted position in which a lug thereof lies within the housing, or substantially so, and an extended position in which the lug extends outwardly through a respective adjacent one of said apertures, the retention devices being movable, with the lugs extended, generally perpendicularly to the plane of said open end to positions in which retraction of the lugs is prevented by cooperation between respective portions of said devices and the housing.

Preferably, positive locking means are provided to act between the retention devices and the housing so as to preclude movement of the devices to positions in which said retraction of the lugs is no longer prevented.

In one convenient arrangement said locking means is a projection extending inwardly from a wall of a respective slot within which a portion of each retention device moves, the projection being resiliently displaceable to permit passage of said retention device portion along the slot to a position beyond the projection and thereafter recovering to perform said locking function.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a perspective view of one form of the wall box of the invention, illustrating a part thereof in detached condition; Figure 2 is a scrap side view of part of the wall box of Fig. 1 in a first operative condition; Figure 3 is a scrap view at right angles to Fig. 2, partly in cross-section; Figure 4 is a view similar to Fig. 2, illustrating a different condition of use; Figure 5 is a scrap view at right angles to Fig. 4, partly in cross-section, and Figure 6 is a detail cross-section along the line A-A of Fig. 4.

The drawings illustrate a wall box which includes a housing 1 for the reception of an electrical accessory such as a switch or socket, the housing having one open end around which is provided a continuous peripheral flange 2 which limits the extent to which the housing 1 may be let into a wall element of a cavity wall, the flange resting against the outer surface of such element when the housing is in its position of use within the wall. A pair of opposed side walls 3 and 4 of the housing are provided with slots 5 and 6, to either side of each of which are respective ones of a pair of internal parallel guide ribs 7 for the purpose to be described. Corresponding pairs of internal guide channels 8 are provided on the base 1A of the housing, being defined by formations 9 which, as can be seen from Figs. 3 and 5, stop short of the side wall 3 to leave gaps 10.The guide ribs 7 and guides 8, for the slot 6 are indentical to those illustrated for the slot 5.

A retention device is provided in association with each of the slots 5 and 6, and one of these being illustrated in detail in Fig. 1 and designated 11. Each retention device has a plate-like body 12 with a lateral flange 13 along its upper edge and a tongue 14 projecting from one side of the body in the opposite direction to the flange 13, the tongue being joined to the body 12 by way of a narrow neck portion 15 so that the innermost edge of the tongue is spaced from the body. A countersunk hole 16 through the flange 13 communicates with an internally threaded boss 17 extending along the rear face of the body 12 perpendicularly to the tongue 14 (Figs. 3 and 6).

Each slot 5, 6 communicates with an opening in the form of a slot 18 extending symmetrically with respect to the slot 5, 6 and parallel with the plane of the open end of the housing, each slot 18 being dimensioned so as to be capable of receiving one of the tongues 14 therethrough, as can be seen from Fig. 2. In the particular embodiment described, the tongue is reinforced by a triangular web 14A extending between the tongue and the body 12, and a further slot 19 is provided in the walls 3, 4 at right angles to and communicating with each slot 18 and dimensioned to permit passage of a web 14A therethrough.

Each slot 5, 6 has, in the illustrated embodiment, a series of pairs of opposed inwardly facing projections 20 on its side walls, those sides 20A of the projections facing away from the open end of the housing being inclined towards said open end to facilitate movement of the retention devices 11 past the projections, as will be described hereafter. The number of projections 20 may be varied as re quired. These projections are capable of slight resilient deformation as a result of the material from which the housing is made and the general deformability thereof is increased by the provision of slots 21 bounding the lateral edges of the apertures 5 and 6. The retention devices 11 are slotted at 22 to enable them to engage the guide formations 9, as can be seen more clearly from Fig. 2.The retention devices may be either provided as separate components, as shown, or rendered captive in the housing with the slots 22 engaged with the formations 9.

When it is desired to mount the wall box in an aperture in a wall element of a cavity wall, the retention devices 11 are slid along the formations 9 to retracted positions, as illustrated in Fig. 3, in which the tongues 14 are withdrawn within the housing body, or substantially so. The housing is then let into the cavity wall to an extent governed by abutment of the flange 2 against the outer face of the wall element, whereupon the projections 11 are moved along the formations 9 until the body 12 abuts the adjacent internal wall of the housing, the tongues 14 then extending to their maximum extent outwardly through the slots 18.In this position, the body is disposed opposite to the gaps 10 at the forward ends of the formations 9 and the devices 11 can now be moved in a direction towards the open end of the housing to bring the neck portion 15 into contact with the inclined faces 20A of the first pair of projections 20. Each retention device can be urged past the respective pair of projections by applying an increased force to the device in a direction towards the open end of the housing in order to deform the projections temporarily outwardly to permit passage of the device, whereupon resilient recovery of the projections brings them into position behind the device to prevent its return movement.Depending upon the thickness of the wall element the retention devices may be moved past a succession of pairs of projections 20 so as to be brought initially close to the internal surface of the wall element prior to mounting of an electrical accessory on the box. Once the devices are in such positions, they are positively retained within the body and are located by the guides 7 in positions of readiness for a final tightening operation. The electrical accessory to be mounted, such a switch or socket, is placed in position within the housing with its standard screw holes aligned with the holes 16 of the retention devices. As the screws are screwed into these holes, the retention devices will be pulled outwardly against the internal wall of the wall element and the assembly will be securely held in position once the fixing screws are firmly tightened.

It will be clear that the shapes and sizes of the various components may be altered at will whilst retaining the overall function of the wall box, as described herein. It will be seen that the invention provides a robust wall box of simple construction and operation which can be readily fixed in position within a cavity wall simultaneously with the mounting of an electrical accessory therein.

Claims

1. A wall box comprising a hollow having one open end with lateral flange means projecting outwardly adjacent said open end, each of two sides of the housing having a respective aperture therethrough, a pair of retention devices each mounted in the housing for sliding movement between a retracted position in which a lug thereof lies within the housing, or substantially so, and an extended position in which the lug extends outwardly through a respective adjacent one of said apertures, the retention devices being movable, with the lugs extended, generally perpendicularly to the plane of said open end to operative positions in which retraction ojf the lugs is prevented by co-operation between respective portions of said devices and the housing.

2. A wall box according to Claim 1 wherein positive locking means are provided to act between the retention devices and the housing so as to preclude movement of the devices from said operative positions to positions in which said retraction of the lugs is no longer prevented.

3. A wall box according to Claim 2 wherein said locking means is a projection extending inwardly from a wall of a respective slot within which a portion of each retention device moves, the projection being resiliently displaceable to permit passage of said retention device portion along the slot to a position beyond the projection and thereafter recovering to perform said locking function.

4. A wall box according to any one of the preceding claims wherein guide means are provided to guide the retention devices during said sliding movement.

5. A wall box according to Claim 4 wherein said guide means is in the form of interengaging formations respectively on each retention device and on the housing.

6. A wall box according to any one of the preceding claims wherein each retention device includes a threaded bore for co-operation by external screw fixing means for an accessory to be mounted on the box, whereby the tightening of such fixing means to secure the accessory in place on the box simultaneously pulls the retention devices towards the open end of the box.

7. A wall box according to Claim 5 wherein each guide means includes a pair of parallel formations projecting from the inner surface of the closed end of the box and providing parallel ribs which are engaged by corresponding slots in the associated retention device, the apertured sides of the box being spaced from adjacent ends of the ribs such as to permit said interengaged formations to disengage at the termination of said sliding movement and permit said perpendicular movement of the devices to their operative positions.

8. A wall box according to any one of Claims 4 to 7 wherein further guide means are provided on the apertured sides to guide the retention devices during said perpendicular movement thereof to their operative positions.

9. A wall box substantially as hereinbefore described with reference to the accompanying drawings.