GB2350729A - Junction box entry ports - Google Patents

Abstract

A junction box for electrical wiring comprises: a base 12 and a substantially continuous side wall 13 upstanding from the base, said side wall having a plurality of ports 14 spaced therearound, each said port having receiving means adapted to receive selectively and removably, as a sliding fit along an insertion axis, a plate 17, each plate having a locking edge 24 provided with locking means extending along substantially the entire length thereof, said locking edge being shaped such that the plate is asymmetric about an axis of asymmetry passing through two points lying on the major surface of the plate, said axis being orthogonal to the insertion axis and lying midway between two extremities of the plate along the insertion axis, said receiving means comprising an engaging edge 25 adapted to engage releasably the locking edge of a respective plate. The plate may comprise a blank 17 or an entry port mount 18 with an entry spout 16.

Description

2350729 IMPROVEMENTS IN OR RELATING TO JUNCTION BOXES The present

invention relates to a junction box for electrical wiring. In particular, the present invention relates to a junction box for use with conduit tubing.

It is known to use junction boxes substantially to enclose electrical connections between several electrical wires, thereby preventing exposure of the electrical connections, which can be unsightly and dangerous. Particularly, such junction boxes are moulded from plastics material such as polyvinyl chloride.

GB 2.301235A discloses a junction box moulded from high density polyvinyl chloride material which comprises a base having a continuous upstandmg wall, the wall being adapted to removably receive separate spouts or blanking plates adjacent respective knock-out holes or ports at locations spaced around the wall. If it is desired to insert a wire into the junction box through a particular knock-out hole in the wall, then the knock-out hole can be removed from the wall thereby forming a port in the wall and a spout can be slidably inserted into grooves formed in the wall, sucli that the wire can pass from the inside of the junction box, through the port in the wall and through the spout located adjacent the port. A length of conduit or tubing can then be inserted into the spout, with the electrical cable passing therethrough such that the cable is substantially completely enclosed. If, on the other hand, it is not desired to insert a cable through a particular knock-out hole in the wall, then a blanking plate can be slidably inserted in a similar way to the spout.

The blanking plates and spout of GB 2301235A comprise generally rectangular, arcuate plates which slide vertically between two grooves formed in a circular wall. At the lower edge of these plates, there is provided a pair of small, downwardly extending tabs which clip into corresponding recesses formed in the base of the junction box. It has been found that this arrangement suffers from two disadvantages. Firstly, quite often when installing blanking plates or spouts, a person is working by feel alone, not being able to see the junction box due to its location. Therefore, it has been found that the blanking plates and spouts of known junction boxes, such as that of GB 2301235A can inadvertently be inserted upside-down, such that the two tabs do not engage the base of the junction box with the result that the spout or blanking plate is not properly retained with respect to the base and side wall. In this condition, the two tabs stand proud of the junction box and are easily darnaged and sometimes broken off. In fact, even when the blanking plates or spouts are inserted with the correct orientation, due to the small size and hence fragility of the tabs, they are vulnerable to damage.

It has been found that the tabs are particularly susceptible to breakage when placed under strain when the junction box is fitted upside down such that the weight of conduit exerts a moment force on the tabs.

It is an object of the present invention to provide an improved junction box for electrical wiring.

Accordingly, one aspect of the present invention provides a junction box for electrical wiring, the junction box comprising: a base and a substantially continuous side wall upstanding from the base, said side wall having a plurality of ports spaced therearound, each said port having receiving means adapted to receive selectively and removably, as a sliding fit along an insertion axis, a plate, each plate having a locking edge provided with locking means extending along substantially the entire length thereof, said locking edge being shaped such that the plate is asymmeti,ic about an axis of asymmetry passing through two points lying on the rmlor surface of the plate, said axis being orthogonal to the insertion axis and lying midway between two extremities of the plate along the insertion axis, said receiving means comprising an engaging edge adapted to engage releasably the locking edge of a respective plate.

Preferably, at least one plate is a blanking plate to close the respective Poll.

Conveniently, at least one plate carries a spout for communication with the respective port.

Preferably, said locking means comprises a lip formed along the locking edge of the respective plate, the plate being resilient.

Advantageously, said engaging edge comprises a recess adapted to receive the lip of a respective plate as a snap fit.

Conveniently, at least one plate is arcuate about its insertion axis.

Preferably, at least one plate is substantially planar.

4 Conveniently, at least one plate is asyrninetric about another axis of asym-metry.

Advantageously, the locking edge of at least one plate is linear.

Conveniently, the locking edge of at least one plate is curvilinear.

Preferably, the locking edge of at least one plate comprises a plurality of linear edge portions.

Advantageously, the arrangement is such that the insertion axis of each said plate is substantially orthogonal to the base.

According to another aspect of the invention, there is provided a plate for use with such a junction box.

In order that the present invention may be more readily understood and so that further features thereof may be appreciated, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure I is a plan view from above of a junction box with two spouts and two blanking plates fitted; Figure 2 is a side elevation of the junction box in the direction of arrow 2 in Figure 1; Figure 3 is a sectional view taken along line 3-3) of Figure 1; Figure 4 is a sectional view taken along line 4-4 of Figure 1; and Figure 5 is a side elevation of three alternative configurations of a blanking plate.

Figure I illustrates, viewed from above, a Junction box 10 according to the present invention. The junction box 10 is preferably moulded from plastics material, such as high density polyvinyl chloride.

The junction box 10 comprises a flat base 12 and a substantially continuous cylindrical side wall 13 upstanding therefrom. Although the junction box illustrated in Figure I comprises a cylindrical side wall 13, it will be appreciated that the side wall could, less preferably, take the form of another geometrical shape, such as a square, a rectangle or a polygon when viewed from above.

At spaced apart locations 14 around the circumference of the wall 12, there are provided circular ports through the wall to allow cables to be inserted through the ports and into the centre of the junction box. The arrangement illustrated in Figure I includes four such ports in the locations 14, although it will of course be appreciated that any number of ports could be provided in the side wall 1-33.

Each port has associated therewith receiving means formed in the side wall I'-). As illustrated in Figure 1, the receiving means takes the form of a pair of spaced-apart grooves 15 in the wall 13, which preferably extend in a direction perpendicular to the base 1.2.

The side wall of the junction box is adapted to have separate spouts 16 or blanking plates 17 selectively removably secured adjacent respective ports. As will be seen from Figure 1, each spout 16 is mounted on a plate 18 of generally similar configuration to the blanking plates 17.

6 The plates 17, 18 have flanges 19 adapted to fit into respective grooves 15, such that the plates 17,18 can be inserted into the side wall 13 by sliding them down an insertion axis substantially orthogonal to the base 12.

As the embodiment illustrated in Figure I comprises a cylindrical side wall then the plates 17,18 are arcuate about their respective insertion axes, having a radius of curvature equal to the radius of the cylindrical side wall 13, such that when installed in the side wall 13, the plates 17, 18 are flush therewith. This arcuate nature of the plates 17,18 and the cylindrical form of the side wall 13 ensures that the spouts cannot be inserted into the wall 13 with the wrong orientation. In the case of plates 18 carrying spouts 16, said wrong orientation is such that the spouts 16 extend inwardly into the junction box 10 rather than outwardly from the junction box 10. Of course, as mentioned above, the side wall 13 may be formed, for example, in the shape of a square, in which case the plates 17,18 would be substantially flat.

Turning now to Figure 2, which illustrates the arrangement of Figure I in elevation viewed along line 2, in the preferred embodiment, the edge profile of the plates 17,18 is curved (at 20) with the receiving portion of the side wall 13 being correspondingly curved so as to receive the plates 17,18. This results in each plate 17, 18 having a degree of asymmetry about an axis (indicated at 21 in Figure 2) passing through two points lying on the major surface of the plates 17,18 but orthogonal to the insertion axis (indicated at 22 on Figure 2) of the respective plate. This means that the plates 17,18 can only be inserted into the receiving means of the side wall 13 to a fully home position in one orientation relative to the side wall 1-3). If the plate 17,18 is inserted into the receiving means in an incorrect orientation, then the plate will not go fully home and will stand proud of the wall. Of course, it will be appreciated that in embodiments where the plates 17, 18 are substantially planar, then it is 7 conceivable that the plates 17, 18 could be inserted into the receiving means of the side wall 13 in two orientations (in the case of plate 18 carrying spout 16, the first orientation being with the spout extending outwardly from the side wall and the second orientation being with the spout extending inwardly). Therefore, in order to limit the number of orientations in which flat plates 17,18 can be inserted into the side wall 13, the plates 17,18 may be given a degree of asymmetry about the insertion axis at the respective plates, as will be discussed in more detail hereinafter.

Along substantially the entire length of the lower, locking edge 23 of each plate 17,18, there is provided an inwardly directed lip 24 (see Figures 3,4). The receiving means of tile side wall 13 is provided with a correspondingly- shaped recess 25 adapted to engage the lip 24 when a respective plate 17,18 is inserted into the receiving means to its fully home position. The plates 17,18 are preferably resilient and so the lip 24 along the locking edge 23 thereof engages into tile respective corre spondingly- shaped recess 25 as a snap fit, thereby preventing inadvertent withdrawal of the plates 17, 18 from the receiving means of the wall 1-33.

The effect of the locking edge 23 of each plate 17,18 being configured such that the plates 17,18 are asymmetric about line 21, and the locking edge being provided with lip 24 along tile entire length thereof is that the plates 17,18 can only be positively locked in position with respect to the wall 13 when they are inserted into the receiving inearis of the wall 13 In a particular orientation relative thereto.

It will of course be appreciated that although the preferred embodiment of the present invention utilises a locking edge 2') curved as shown in Figure 2, the locking edge 2') of each plate 17, 18 could be configured in numerous other ways, such as those illustrated in Figure 5. Figure 5(a) illustrates the locking edge 5 as being linear, such that all points along the locking edge 23 lie in a single plane orthogonal to the insertion axis of the plate 17, and the plate is asymmetric about its insertion axis 22 as well as about the line 2 1. Figure 5(b) illustrates a blanking plate 17 having a curvilinear locking edge 23 3 shaped such that the plate 17 is again asymmetric about its insertion axis 22 as well as about line 2 1.

Alternatively the locking edge 235 of each plate 17,18 may comprise a plurality of linear edge portions such as the plate 17 illustrated in Figure 5(c). A preferred variation on this embodiment is to radius the corners of the plate 17,18 along the locking edge 23) so that the overall shape of the plate is rectangular but with two rounded corners along the locking edge 23. This alTangement is especially preferred when the spout 16 mounted on the plate 18 is rectangular and not circular in section.

It is possible to provide each junction box with a number of spouts 16 of different diameters to one another to receive different sizes of cable and conduits. Further, the shape of the spouts 16 can be varied to attach to and accommodate conduit of different shapes. Thus, although only circular spouts 16 have been described, rectangular spouts are also envisaged.

It is to be appreciated that whilst the present invention has been described with reference to specific embodli-nents, various modifications to the junction box could be effected without departing from the scope of the invention.

In the present Specification the word "comprise" or "comprises" means "including or consists of' and "compi.ising" rneans "including or consisting of'.

Claims (16)

9 CLAIMS

1. A junction box for electrical wiring, the junction box comprising: a base and a substantially continuous side wall upstanding from the base, said side wall having a plurality of ports spaced therearound, each said port having receiving means adapted to receive selectively and removably, as a sliding fit along an insertion axis, a plate, each plate having a locking edge provided with locking means extending along substantially the entire length thereof, said locking edge being shaped such that the plate is asymmetric about an axis of asymmetry passing through two points lying on the major surface of the plate, said axis being orthogonal to the insertion axis and lying midway between two extremities of the plate along the insertion axis, said receiving means comprising an engaging edge adapted to engage releasably the locking edge of a respective plate.

2. A junction box according to claim 1, wherein at least one plate is a blanking plate to close the respective port.

3. A junction box according to claim 1 or 2, wherein at least one plate carries a spout for communication within the respective port.

4. A junction box according to any preceding claim, wherein said locking means comprises a lip formed along the locking edge of the respective plate, the plate being resilient.

5. A junction box according to clairn 4, wherein said engaging edge comprises a recess adapted to receive the lip of a respective plate as a snap fit.

6. A junction box according to any preceding claim, wherein at least one plate is arcuate about its insertion axis.

7. A junction box according to any preceding claim, wherein at least one plate is substantially planar.

8. A junction box according to any preceding claim, wherein at least one plate is asymmetric about another axis of asymmetry.

9. A junction box according to any preceding claim, wherein the locking edge of at least one plate is linear.

10. A junction box according to any one of claims 1 to 8, wherein the locking edge of at least one plate is curvilinear.

11. A junction box according to any one of claims 1 to 8, wherein the locking edge of at least one plate comprises a plurality of linear edge portions.

12. A junction box according to any preceding claim, the arrangement being such that the insertion axis of each said plate is substantially orthogonal to the base.

1 J3). A plate for use with a junction box according to any preceding claim.

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

15. A plate substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

16. Any novel feature or combination of features disclosed herein.