AU689563B2

AU689563B2 - Improved junction box

Info

Publication number: AU689563B2
Application number: AU20103/95A
Authority: AU
Inventors: John Hajje
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-07-12
Filing date: 1995-05-18
Publication date: 1998-04-02
Anticipated expiration: 2015-05-18
Also published as: AU2010395A

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

NOTICE

1. The specification should describe the invention in full and the best method of performing it known to the applicant.

2. The specification should be typed on as many sheets of good quality A4 International size paper as are necessary and inserted inside this form.

3. The claims defining the invention must start on a new page. If there is insufficient space on this form for the claims, use separate sheets of paper.

The words "The claims defining the invention are as follows" should appear before claim 1. After the claims the date and the name of the applicant should appear in block letters.

4. This form must be accompanied by a true and exact copy of the S, description, claims and drawings (if any) and an additional copy of the claims.

(see Pamphlets explaining formal requirements of specifications and drawings) TO BE COMPLETED BY APPLICANT VkA John HAJJE, n n N am e of A pplicant: John HAJJE A ctual Inventor(s): t a f D A I t+(i M1"c'^^ .*..Address for Service: 44 ASHLEY HORISBY PO IoX 2.

9 6 N.SA *e77, AUSTAL A iVe. DOC)OC.' NS V'i JI O- I h IMPROVED JUNCTION BOX inventio n T itle PM 6779 (12th July, 1994) Details of Associated Provisional Applications: Nos: The following statement is a full description of this invention, including the best method of performing it known to me:i -2- IMPROVED JUNCTION BOX This invention relates generally to fittings for use with concealed electrical cables and junction boxes in particular.

It is common for junction boxes to be buried in poured concrete slabs along with conduits thereby allowing wires to be subsequently installed in a concealed manner. The term junction box as used herein is to be interpreted generally but of necessity would include a chamber with one or more socket members each adapted to receive the end of a length of conduit.

Junction boxes for the above purpose are known. There has been a problem with known junction boxes in that the manufacturers have only considered the functional requirements of the junction box. Substantially no consideration has been given to :oe the practical problems confronting an electrician in drawing e15 wires through conduits into the chamber of the junction box.

oe A major problem for the electrician is that in known junction S boxes there is a "square" corner at the junction of the bore of the socket member with the chamber of the junction box. The 60000 square corner requires the wires being drawn to undergo a very S 20 abrupt direction change in passing from the conduit to the junction box chamber. There is an associated large frictional drag over the sharp corner and the result is that the large forces are required to draw the wires into the junction box chamber.

The forces applied in some instances can result in damage to the wires or their insulation. In extreme cases a jammed situation can result where the wire drawing operation has to be aborted, the wires have to be withdrawn from the conduit and the operation recommenced.

The present invention provides a solution to the above problem and in addition also provides further advantages for junction boxes which enables them to be readily mounted in place on concrete formwork prior to being buried by a concrete pour.

Broadly stated the present invention provides An electrical wiring junction box, said junction box including a body, a chamber in the body defined by wall means including a side wall disposed about an axis extending between a compartment end wall and an open end of said compartment, a closure member for the open end of said chamber, means allowing said closure member to be removably secured to said body to cover said open end, at least one conduit socket extending outwardly from said body and disposed at or adjacent the compartment end wall, an open ended bore extending through each socket to provide unimpeded access to said chamber, each said socket bore has an axis lying at an angle to said compartment axis, a bearing surface means 15 at the intersection of each socket bore with said chamber wall means, said bearing surface means extending along portion of said intersection and lying at an angle to both the compartment and the socket axes and providing an extended friction minimising transition surface between said socket bore and said 20 chamber wall means, said portion of said intersection is located so as to be engaged by wiring when drawn into said compartment towards the open end of said compartment from said socket bore and by wiring when drawn from said compartment through said conduit socket, said bearing surface has a breadth which decreases away from a zone of said bearing surface which lies closest to the open end of said chamber and which reduces S4 in width in both directions from said zone and at its ends blends into said intersection.

A presently preferred embodiment of the invention will now be described with reference to the accompanying drawings in which: Fig. 1 is a cross-sectional elevation of a junction box according to the invention including a removable cover for the open end of the chamber of the junction box body, Fig. 2 is an enlarged fragmentary view of the intersection f 735 between a conduit socket and the wall of the chamber of the -3ajunction box illustrating the paths followed by a drawn wire in a conventional junction box and the junction box of this invention, Fig. 3 is a view on the section line 3-3 of Fig. 1, and Figs. 4 and 5 illustrate alternative profiles for the bearing surface between a conduit spigot bore and the wall of the chamber of the junction box.

o o -4- The junction box 1 has a body 2 with a chamber 3 defined by wall means comprised of an end wall part 4 and a side wall part The body has two external conduit sockets 6 and 7 with bores 8 and 9 providing access from outside of the body to the chamber 3 at locations remote from the open end of the chamber The bores 8 and 9 are respectively counter bored at 10 and 11 to accept the ends of conduit.

It is to be understood that the junction box 1 may be provided with only one of the conduit sockets 6/7 and may have more than two conduit sockets mounted on and extending away from the outer surface of the body 2. It would also be possible to have conduit sockets, such as 13, on the end 12 of the body 2 as S shown in broken lines.

The invention has applicability to conduit sockets where the oooo 15 axis of the bore through the conduit socket lies at an angle to e the axis X X. The invention would not have relevance to a conduit socket where the conduit spigot bore axis is aligned with the axis X X, as in such cases wires being drawn would not undergo any substantial angular deviation in entering the 20 chamber from the conduit socket.

.eeooi There is a removable cover 15 for the chamber open end. The cover 15 is secured by screws entered into threaded bores in diametrically opposed bosses 16 within the chamber 3.

In Figs. 1 and 2 it will be seen that at the intersections of the socket bores 8 and 9 with the chamber 3 there are bearing surfaces indicated 19. The bearing surfaces 19 extend over at least that portion of the intersection on which a wire would bear in being drawn through said conduit socket and out through the open end of the chamber. As a general rule the bearing surface would be that portion of the intersection closest to the open end of the chamber. The bearing surface 19 can be in the form of chamfer, or a curve or may be multi-faceted. The bearing surface 19 breaks what would be otherwise a high friction sharp edge over which wires would have to pass as they were drawn from the conduit socket to the open end of the junction box chamber.

As illustrated in sectional views in Figs. 1 and 2 the chamfer 19 comprises a flat surface which is at its maximum width closest to the open end of the chamber. The chamfer reduces in width in both circumferential directions away from its maximum width to points of extinction indicated 25 where it intersects the junction line of the conduit bore and the chamber wall Half of the chamfer is represented in Figs. 1 and 2 (because of the section plane) as a triangle identified 26 with sides A, B,

C.

Figs. 4 and 5 illustrate alternative curved and multifaceted 4l profiles for the bearing surface 19.

The advantage achieved by using the junction box of the 15 invention can be best seen from Fig. 2 by comparing the wire travel paths shown in broken lines. The path 21 is that followed by a wire being drawn into the chamber 3 from the bore of the conduit spigot in a conventional junction box. The path oo.. 22 is that followed by a wire being drawn into the chamber 3 from the bore of a conduit spigot 7 in a junction box according to the invention. Clearly the path line 22 will facilitate the movement of the wire and will require less drawing force because of the gradual transition from the axial direction of the bore of the conduit spigot to the axial direction of the junction box chamber.

The foregoing description has dealt principally with the junction box body 2 and has referred generally to the cover for the junction box. It is to be understood that the cover as shown in Figs. 1 and 2, can take a number of forms. The specific form illustrated in Figs. 1 and 2 comprises a circular pare 26 with a central upstanding boss 27 of different diameter thereby to provide a shoulder 28 which will be held against ;he end 29 of the body 2 by means of screws entered into the threaded bores of the bosses 16, as previously described. The -6cover 15 has lugs 30 with holes. In a junction box mounting operation the junction box body 2 is held to the cover 15 by screws entered into the bosses 16 and the cover 15 is held to the formwork by nails passing through holes in the lugs 30 of the cover. It is to be understood that the lugs 30 can be of any number, three are shown in Fig. 3.

In use, the junction box will be embedded in concrete and the cover 15 will be exposed by the ."tripping of the concrete. The formwork in the stripping operation will strip from the nails passing through the lugs 30. By removing the screws securing the cover 15 to the body 2 the cover 15 with the nails can be removed and the nails can then be removed and discarded. Once e this has been done the cover 15 can be replaced and if desired the lugs 30 can be simply removed from the outer edge of the 15 cover 15 by means of a knife or snips or other tool.

eoee "This arrangement has the double advantage of providing the outer face of the cover 15 in a plane flush with the bottom of *the poured concrete slap and facilitates the removal of the nails whereby the junction box was held to the formwork during 20 the concrete pour.

a The nature of the components hereinbefore described makes them a a S. ideally suited for moulding in plastics material.

a.

The foregoing is to be considered as illustrative of preferred embodiments of the invention and it is to be understood that changes can be made to features of the specific embodiments described without departing from the inventive concepts disclosed. For example the junction box can have any crosssectional shape and need not necessarily be of circular configuration.

The conduit sockets can be other than 'square' to the axis of the chamber, as illustrated 6a in broken lines in Fig. 1.

I- I I The lugs 30 of Fig. 3 can be of the elongated form shown in Fig. 3 and marked 31 provided with slots 32 allowing the junction box to be rotationally positioned on the formwork after initial fixing by nails of screws.

O

9 9 *o

I

Claims

1. An electrical wiring junction box, said junction box including a body, a chamber in the body defined by wall means including a side wall disposed about an axis extending between a compartment end wall and an open end of said compartment, a closure member for the open end of said chamber, means allowing said closure member to be removably secured to said body to cover said open end, at least one conduit socket extending outwardly from said body and disposed at or adjacent the ooeo 10 compartment end wall, an open ended bore extending through each 0 socket to provide unimpeded access to said chamber, each said o S"socket bore has an axis lying at an angle to said compartment axis, a bearing surface means at the intersection of each socket bore with said chamber wall means, said bearing surface 00 000000 S 15 means extending along portion of said intersection and lying at an angle to both the compartment and the socket axes and .providing an extended friction minimising transition surface between said socket bore and said chamber wall means, said portion of said intersection is located so as to be engaged by wiring when drawn into said compartment towards the open end of said compartment from said socket bore and by wiring when drawn from said com[:rtment through said conduit socket, said bearing surface has a breadth which decreases away from a zone of said bearing surface which lies closest to the open end of -9- said chamber and which reduces in width in both directions-from said zone and at its ends blends into said intersection.

2. A junction box as claimed in claim 1 wherein the bearing surface is flat in its breadth direction.

3. A junction box as claimed in claim 1 wherein the bearing surface is convexly curved in its breadth direction.

4. A junction box as claimed in claim 3 wherein the curvature of the convexly curved bearing surface is comprised of a e plurality of facets extending in the length direction of said og 10 bearing surface.

5. A junction box as claimed in any one of the claims 1 to 4 wherein the closure member is provided with a plurality of fixing lugs which extend outwardly from the closure member sufficiently to extend beyond said body when said closure member is fixed to said body.

6. A junction box as claimed in claim 5 wherein said lugs include slots to allow limited rotation of said junction box after connection of the junction box to a support means by fasteners located in said slots.

7. A junction box as claimed in any one of the claims I to 6 wherein said closure member includes locating means to engage said chamber side wall and thereby position said closure member relative to said body.

8. A junction box as claimed in any one of the claims 1 to 7 including a conduit receiving bore enlargement at the outer other end of each spigot bore.

9. A junction box substantially as hereinbefore described with reference to any one of the accompanying drawings. Dated this 28th day of January, 1998 JOHN HAJJE SBy his Patent Attorneys CARTER SMITH BEADLE. a. o a. a. a *4 I II