AU2498099A - Cable ducting system and parts thereof - Google Patents

Description

-1- Regulation 3.2

AUSTRALIA

PATENTS ACT, 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address for service in Australia: Invention Title: PDL INDUSTRIES LIMITED HENDRIK CHRISTIAAN DORLAS A J PARK SON, Level 11, 60 Marcus Clarke Street, Canberra ACT 2601 Cable Ducting System and Parts Thereof The following statement is a full description of this invention, including the best method of performing it known to me/us -2- The present invention relates to a cable ducting system and to one or more of the individual parts thereof and methods of use thereof, and in particular to cable ducting systems for installation in conjunction with a concrete floor slab.

In the prior art it is known to provide simple cable ducts in concrete floor slabs by pouring the concrete around the pre-situated duct or by fitting the duct into a pre-formed channel after formation of the concrete slab. In general these ducting installations have been custom made for each job and have not involved a systematic type scheme suitable for efficient design, manufacture and installation.

It is therefore an object of the present invention to provide a cable duct system and/or parts thereof, and/or methods of installation thereof which go someway towards overcoming the above disadvantages or which will at least provide the public with a useful choice.

In a first aspect the invention consists in an adjustable support for a trough of an in floor cable duct installation comprising; a support frame having a base plate and a pair of upstanding symmetrical side plates extending upwardly along opposed edges thereof and separated by at least the width of a trough intended to be accommodated, and a spanning support member adapted to span between said side plates, said .side plates each including a plurality of support means having a variety of vertical 20 displacements from said base plate, each to support one end of said spanning support member.

In a further aspect the invention consists in a blank for a support frame as described above or as herein described with reference to and as illustrated by Figures 2 to 4 of the accompanying drawings.

25 In a further aspect the invention consists in a blank for an adjustable support for a trough of an in floor cable duct installation comprising: o0•O a generally rectangular web portion defined by a pair of opposed edges and a pair of opposed perforation or score lines, and a pair of side plate forming webs extending outward from said perforation or score lines, the edge of each said side plate forming web opposite their respective said perforation or score line having a plurality of support locations, each said -3support position of one side member forming web having a corresponding symmetrically opposed position on the other said side plate forming web, said locations at a plurality of distances from their respective said perforation or score line, said side plate forming webs intended to be folded upward and toward one another in use to an angle of approximately 900 to the rectangular web, and each symmetric pair of support positions to cooperate with a spanning support member adapted to span between said side plates.

In a further aspect the invention consists in a cable duct for installation in a concrete floor slab comprising an elongate trough portion having an upstanding elongate partition dividing said trough portion into a pair of parallel elongate panels along substantially the entire length thereof, said upstanding partition having substantially the same height overall as the defining walls of said trough portion, and an elongate lid for enclosing said trough portion, connectable at its edges to said defining walls of said trough portion and spanning there between so that said partition substantially fully divides the thereby defined space into two parallel spaces, said duct having open ends for connection with any one of a variety of connectors or caps.

In a further aspect the invention consists in a connector for use in a cable duct installation in a concrete floor slab capable upon installation of assuming a number 20 of modes, comprising, prior to installation, a longitudinally extending trough portion S-defined by a floor and a pair of opposed sides, said sides having connection means on the top edge thereof to facilitate the connection of a cover plate, the ends of said trough portion adapted to have ducts connected thereto, and each opposed side of said trough portion including perforations therein, which facilitate the creation of an 25 opening in the side by folding down a floor portion of the side and folding outward a 0 0. pair of wall portions, which together define a further opening for connection of a 0090 further duct.

In a still further aspect the invention consists in a blank for a connector for 0 use in a cable duct installation, wherein said blank comprises a generally rectangular web having a pair of parallel score lines there across parallel with a pair of edges of said web, each score line associated with a said edge, and spaced equidistantly -4therefrom, said spacing defining the intended height of said connector, said parallel score lines being separated by a distance substantially the same as the width of a cable dust of the installation, and for each said score line and associated edge, a pair of potential fold lines, being scored or perforated and extending perpendicularly from each score line to its associated edge, said pair separated by substantially the width of a said duct, a pair of potential vertical cut lines, being cuts, or broken cuts, extending perpendicularly between said score line and said associated edge, and located between said pair of potential fold lines, and a pair or potential horizontal cuts, being either cuts or broken cuts, each extending along said score line, from the point where one of said potential folds meets said score line to the point where the adjacent said potential vertical cut meets said score line.

In a still further aspect the invention consists in a connector for use in a cable duct installation formed from a blank as set forth above by folding up the regions between each score line and its associated side along each said score line to thereby form a longitudinal trough, where a flanged opening may be achieved in each or either side wall by forming the appropriate potential cuts (if not already formed), folding out a pair of vertical flanges about the potential fold lines, and folding down any remaining section of the wall between said flanges.

In a still further aspect the invention consists in a joint between two or more 9*9* 20 cable ducts and incorporating a connector as described in any of he above :paragraphs wherein a pair of said cable ducts extend into said trough through the o999 .ends thereof, and one or more ducts are engaged with said formed openings, at least between said formed flanges, said ducts being as described in the above paragraph, :"and having a said upstanding dividing wall running longitudinally there through, °9* S 25 there being a horizontal separating plate in said trough of said connector, having a slot at each end thereof extending into said plate in the longitudinal direction of said ducts, said slots in registration with said upstanding dividing walls, and being disposed about the ends thereof.

In a still further aspect the invention consists in a system for a cable duct installation incorporating one or more components according to any one of the above paragraphs, together with any further components as may be desired, such as corner connectors, ends or the like.

In a still further aspect the invention consists in a cable ducting system substantially as herein described with reference to and as illustrated by the accompanying drawings.

In a still further aspect the invention consists in a method of installation of a cable ducting system substantially as herein described with reference to and as illustrated by the accompanying drawings.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

The preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which; Figure 1 is a cross-sectional view through a section of straight run cable trough, Figure 2 is a perspective elevation of an adjustable support for a cable trough of Figure 1, including supporting bar, Figure 3 is a plan view of a sheet metal blank used for forming the support of oooo 20 Figure 2, Figure 4 is a perspective view of a floor slab under construction which incorporates the cable ducting system, demonstrating the application of the adjustable supports with a cable trough, :Figure 5 is a perspective view of a right-angle corner connector according to 25 the cable trough system of the present invention, Figure 6 is a perspective view of a straight line connector for connecting two runs of cable trough end to end according to the cable trough system of the present invention, Figure 7 is a perspective view of a 45 o corner connector according to the cable trough system of the present invention, Figure 8 is a perspective view of an end cap according to the cable trough system of the present invention, Figure 9 is a plan elevation of a blank for a T or X junction connection according to an embodiment of the cable trough system of the present invention, Figure 10 is a perspective elevation of a T junction formed from the blank of Figure 9, Figure 11 is a plan elevation of a divider for use with the junction of Figures 9 and With reference to the figures, the preferred embodiment of the cable trough system comprises a number of different components. Preferably it includes a standard cable trough 1 as depicted in Figure 1, a variable level support 2 such as depicted in Figure 2, corner connectors such as the right-angle connector 3 of Figure and the 45 connector 5 of Figure 7, connectors for connecting two runs of trough end to end such as straight connector 4 in Figure 6, end caps to enclose the ends of runs of troughing such as the end cap 6 shown in Figure 8 and cross or T junctions, which may be formed from for example the multi-purpose junction unit 8 of Figures 9 to 11. Each of these components will be described briefly in turn with their implementation and use described as appropriate, along with a summary of installation of a system according to the preferred embodiment of the present invention.

20 With particular reference to Figure 1, a standard run cable length 1 is shown in cross-section wherein a trough 11 has upstanding sides 12, 13. A pair of inwardly

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extending side flanges 16 extend perpendicularly inwards from the top of the upstanding side walls 12, 13 to allow for connection of a cover 14. The cover 14 is preferably secured by fasteners such as counter-sunk screws passing through the 25 cover 14 into the flanges 16. A dividing wall 15 is preferably provided in the troughing 1 to divide the trough into two runs, one for accommodating power type cables and one for accommodating data type cables. The dividing wall 15 has a perpendicularly extending flange 18 at the top thereof to mate against the cover 14, "•and to which the cover 14 may also be secured, although this is not really necessary,

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as the cover 14 can be adequately secured just to the side flanges 16. The dividing wall is preferably secured to the troughing 1 by a bottom flange 17, and may for -7example may be rivetted or spot welded in place.

As with the other components of this system, the troughing 1 is intended for construction from sheet metal, which is durable and can be readily formed by cutting and folding operations. Other suitable materials might be used without departing from the scope of the invention.

The cable troughing of Figure 1 is preferably of substantially constant crosssection, and provided in basically straight runs of standard length and along with sections cut to particular lengths in accordance with a schematic layout of the cable trough system to be installed.

With reference to Figure 2, an adjustable support for a trough such as that shown in Figure 1 is depicted. The adjustable support has a base member 21 with side walls 22, 23 extending upwardly from the closed edges thereof. The side walls 22, 23 have a series of steps at different levels, so that a supporting member or rod can span between the side walls 22, 23 and, depending upon which step 24 the rod 25 rests, the support will support a trough at a given level. The steps 24 preferably have a surface form to retain the rod or support 25 in a stable manner.

Each side wall 22, 23 preferably has one or more holes 26 which are preferably *formed close to the lower edge thereof, and which may be used to secure the adjustable support 2 to for example the reinforcing structure of a concrete slab to be 20 poured, and to secure the pre-laid trough sections 1 thereto so that the trough is

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retained accurately in position at a certain level with respect to the slab reinforcing S:and hence the slab surface during pouring of the concrete slab and sections of the trough installation are not able to be moved from position, for example by floating in the concrete.

A blank 27 for forming a support 21 is depicted in Figure 3, with each of the features shown in Figure 2 clearly visible. The blank may be formed into the support 21 by folding up along fold lines 28.

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S"Use of the trough support 21 for supporting a cable troughing section 1 is depicted in basic form in Figure 4, although not to scale. The concrete slab to be formed will include reinforcing, such as a large gauge reinforcing mesh 9, with the support 2 secured to the mesh 9 by wiring down with wires 29 passing through the holes 26 which are provided for that purpose. As can be seen in Figure 4 the trough support can be used to ensure the level of the trough 1 relative to the horizontal plane, as may be gathered by use of a level or by using level string type methods, by positioning supporting rods in the appropriate steps 24 of the various supports used.

Once the entire troughing system has been assembled, with the covered components thereof fixed, it is recommended that the trough also be wired or otherwise secured to the adjustable support 2.

For some installations the troughing may be being used in concrete slabs of large thickness where the adjustable support must be positioned above the level of the reinforcing mesh. In such situations the installer can for example pour a lump of concrete and position the adjustable support thereon to elevate it above the level of the reinforcing mesh. The adjustable support can be wired to the concrete lump if this is arranged when the concrete is freshly poured. Furthermore it may be that the installation is being provided in a slab which is not sufficiently deep to have the adjustable support positioned on top of the reinforcing mesh, in which case the supporting trough may be positioned under the reinforcing mesh and passing through slots or cuts formed therein, or otherwise passing through the mesh. Clearly also for other forms of concrete slab, for example where reinforcing mesh is not being used, many manners and methods for securing the adjustable support would be applicable 20 and within the scope of the present invention.

To be used to its greatest advantage, the cable troughing system must fit together easily and efficiently with standardised type components, in a manner in which poured concrete will not enter the troughing, for example through gaps, open ends, poorly assembled joints or the like. To this end, various connectors and end caps are preferably provided, such as those shown in Figures 5 to 8.

With reference to Figure 5 a right-angle corner connector 3 is shown which has a base member 30, upstanding outer wall 31 and inner wall 34. A cover 32 is S"fitted to the corner connector, and preferably secured to inwardly extending flanges 33. As with the straight troughing the cover 32 is preferably secured by for example counter-sunk screws which may be self-threading for convenience. As with the cable troughing, it is considered desirable to maintain the separation of data and electrical -9power supply cables and to this end a divider 35 is provided in the corner connector 3, which may be secured to the corner connector 3 with a bottom flange 36 for example by rivetting or spot welding. The cable troughing of Figure 1 has the internal divider thereof provided closer to one side than the other to provide more space for example in the data cable compartment, and to this end the comer connector divider 35 is preferably provided closer to the inside or closer to the outside as appropriate for the direction of the corner which is contemplated. In use, the end of a trough section is intended to be disposed slightly within the connection ends of the comer connector so that the dividing wall 15 of the straight trough comes more or less into abutment with the ends of the dividing wall 35 of the comer connector, there then being a significant overlap between the ends. The straight trough can then be rivetted or otherwise secured in place, for example through the side walls 31 and 34 and side walls of the trough. The entrances to the comer connector are preferably sized to closely accommodate the external dimensions of the trough.

With reference to Figure 6, a connector is shown for joining two straight trough parts, the connector 4 being configured to fit around the outside of the bottom and two sides of the two end abutting trough sections. The connector 4 has a base member 41 and upstanding side walls 42 with preformed holes 43 there through, 20 which may be used for example to rivet the connector 41 to the troughing joining the side walls 42 of the connector 4 to the side walls of the troughing. A connector of S-this type substantially prevents any concrete entry into the troughing during pouring of the concrete slab.

With reference to Figure 7, a 450 corner connector 5 is shown which more or less corresponds with the connector 3 of Figure 5 but with a lesser angle of corner.

The connector 5 has a base member 50, upstanding side walls 51 and 54 being outer S"and inner side walls respectively. A cover 52 is fitted to the connector 5 by flanges S"53 extending inwardly from the top of the side walls 53 and 54. A divider 55 is secured to the base member 50 through a horizontally extending flange 56. As with the right angle corner connector 3, the 45 0 corner connector 5 is intended to have the ends of troughing sections accommodated overlapping therein. It is to be noted that with the connectors of Figure 5 and Figure 7 the covers 32 and 52 do not cover the entirety of the base member 30, 50, as the troughing covers will cover the remaining portion themselves.

With reference to Figure 8, an end cap 6 is shown which has an end face designed to enclose the open end of a troughing section, the end cap having side walls 61 and bottom wall 62 extending perpendicularly therefrom to overlap around the side walls and bottom wall of a straight troughing section and to be secured thereto, for example by rivetting.

A cable trough installation may also require the provision of T or cross-type junctions wherein cables can diverge or converge or change paths. To these ends, with reference to Figures 9 to 11, a multi-purpose connector in provided in the preferred embodiment of the present invention. The multi-purpose connector 8 is formed from a blank 90. The connector 8 has a base member 80, and upstanding side walls 81, resembling substantially a straight trough section. Each side wall is provided with a number of slots and potential fold lines to allow a flanged opening to be produced in either of the sides to accommodate the end region of a straight troughing section.

In the particular embodiment shown it is preferred that a pair of potential S vertical fold lines 86 is provided with a pair of cuts or almost-cuts 87 extending from 20 the bottom end of the fold lines 86 toward the other fold line 86 for a short distance and then extending upwardly as cuts or almost-cuts 88 to thereby allow the formation, by completing the cuts 87 or 88 if uncompleted, and folding out the tabs 83 defined by the fold lines 86 and cut or potential cut lines 87 or 88 to form a pair of side flanges 83. A fold line or potential fold line 85 is provided along the bottom edge, so that the resulting central part can be folded down to form a partial bottom flange which, although it does not fully extend across the width of a troughing entered there between, does at least substantially enclose the join between the bottom of the trough and the base member 80 of the connector 8.

The connector 8 preferably has a plurality of folded over tabs 89 to which a cover can be secured. With reference to Figure 9, the blank for the connector 8 is shown, with the various cut and potential cut lines shown, and the fold lines 91 for -11folding up the sides 81 also depicted. Clearly if the system is provided in blank rather than folded up form, then each connector may be formed as appropriate and the various cuts and folding out of the flanged opening parts 83 or 84 may occur before folding up the sides 81. It is preferred for ease of folding that in an in situ type situation the potential fold lines 86 and 85 are either deeply scored or are of a perforated type form.

With reference to Figure 11, in a cross or T connector, it is still considered desirable to keep the data and power cables separated and to this end a horizontal divider 92 is provided which fits within the connector 8 above and parallel with the base member 80 thereof and in the space bounded by the two upstanding side walls 81. The divider 92 has a pair of slots 93 extending inwardly from opposed edges thereof, which serve to locate the divider by having the dividing wall 15 of the straight run troughing extending into the slots 93. As with the right angle and 450 corner connectors, the straight run troughing preferably passes into the connector 8 to substantially overlap therewith, and be connected to either the base or side walls, or folded out flanges thereof by for example rivets. With the horizontal divider 92 cables are preferably routed over or under the divider depending on whether they are *o o data or power cables, and when exiting the connector pass into the corresponding channel of the straight run troughing.

20 In use, the system of the present invention, and as described above, is preferably pre-located on the reinforcing laid out for formation of the concrete slab other ground work and slab foundation as appropriate to the installation in question. The system laid out is preferably a pre-designed layout comprising a collection of various of the parts described above, with multiples of parts being used wherever appropriate. In use it may be necessary for outlet boxes also to be provided, for example at a short distance from the cable trough, in which case these can be provided also in the floor slab with data and power cable conduits extending .9 9 S"thereto from the cable trough. These conduits may for example comprise standard PVC plastic piping, with one or other of the data or power conduits passing underneath the trough to exit the cable trough on the appropriate side. Again such elements of the installation should be pre-positioned before pouring of the concrete -12slab. The entire pre-located installation should be carefully levelled up by adjustment of the adjustable supports which support at least the straight run sections of trough, prior to pouring the concrete slab. Where necessary the adjustable supports may also be used to support other elements of the system, for example the corners or T- or Xtype junctions, by inserting the low end of the adjustable support under the comer connector or junction box from one side thereof. The further the adjustable support overlaps the connector, the higher the connector will be supported, resting on the flats 95 of a step of the support. Clearly more than one of the supports 2 may be used if space allows.

As earlier described, the supports should be secured to the reinforcing of the concrete slab, and the troughing be secured to the supports, prior to pouring of the slab. It is preferred that prior to pouring the concrete slab all the cover portions for the various components of the system are secured in place and an adhesive tape is applied along each edge of for example the trough or cover plates to enclose and seal any gaps between adjoining parts, so that any moisture or lying water inherent in the concrete slab pouring process is not able to enter the trough network. Once the slab has been poured and has cured, the portion of the tape visible above the level of the oooo concrete slab can be removed, for example by cutting to the slab edge with a knife and then peeling away. This ensures an accurately positioned, laid out and 20 configured system, which is essentially integral with the floor slab.

With its modular and repeated components this system allows simple design S"of installations and ease of assembly. The trough supports are easy to configure and adjust and the supporting bars 25 may for example comprise sections of reinforcing bar being used in the reinforcing of the concrete slab. In this way many advantages are realised by the system and any one or more of the components and the method of installation of the system.

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Claims (23)

1. An adjustable support for a trough of an in floor cable duct installation comprising; a support frame having a base plate and a pair of upstanding symmetrical side plates extending upwardly along opposed edges thereof and separated by at least the width of a trough intended to be accommodated, and a spanning support member adapted to span between said side plates, said side plates each including a plurality of support means having a variety of vertical displacements from said base plate, each to support one end of said spanning support member.

2. An adjustable support as claimed in claim 1 wherein said plurality of support means comprise a plurality of steps in the top edge of each said side plate.

3. An adjustable support as claimed in claim 2 wherein each said step of said top plate edge includes a detent therein, said support member adapted to settle in said detents to be located thereby on said step.

4. An adjustable support as claimed in either claim 2 or claim 3 wherein said top .:.*.edges are formed with more or less a staircase of said steps rising steadily in displacement from said base plate. 20

5. An adjustable support as claimed in any one of claims 1 to 4 wherein said S"side plates each have one or more holes extending therethrough adjacent the bottom edge thereof, through which wire or reinforcing rods may be passed to secure the support frame to the reinforcing of the concrete slab floor and to secure the trough to the support plate.

6. A blank for an adjustable support for a trough of an in floor cable duct installation comprising: ~a generally rectangular web portion defined by a pair of opposed edges and a pair of opposed perforation or score lines, and a pair of side plate forming webs extending outward from said perforation or score lines, the edge of each said side plate forming web opposite their respective said perforation or score line having a plurality of support locations, each said -14- support position of one side member forming web having a corresponding symmetrically opposed position on the other said side plate forming web, said locations at a plurality of distances from their respective said perforation or score line, said side plate forming webs intended to be folded upward and toward one another in use to an angle of approximately 900 to the rectangular web, and each symmetric pair of support positions to cooperate with a spanning support member adapted to span between said side plates.

7. A blank as claimed in claim 6 wherein said plurality of support positions comprise a plurality of steps along the outside edge of each said side plate forming web.

8. A blank as claimed in claim 7 wherein each said step of said outer edge includes a detent therein, adapted to locate a said spanning support member in use.

9. A blank as claimed in either claim 7 or claim 8 wherein said blank has overall a trapezoidal outline, said outer edges being the non parallel opposed pair of sides of said trapezoid, and said plurality of steps are spaced along said outer edges in more or less a staircase arrangement. A blank wherein each said side plate forming web has one or more holes .extending therethrough adjacent said perforation or score line, through which in use, with said blank folded to form a trough support, wire or reinforcing rods may be S 20 passed to secure the support frame to the reinforcing of the concrete slab floor and to secure the trough to the support plate.

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11. A support for a trough of an in floor cable duct installation formed from a blank as claimed in any one of claims 6 to 10 by folding up and toward one another said side plate forming webs about said perforation or score lines.

12. A cable duct for installation in a concrete floor slab comprising an elongate trough portion having an upstanding elongate partition dividing said trough portion into a pair of parallel elongate panels along substantially the entire length thereof, said upstanding partition having substantially the same height overall as the defining walls of said trough portion, and an elongate lid for enclosing said trough portion, connectable at its edges to said defining walls of said trough portion and spanning there between so that said partition substantially fully divides the thereby defined space into two parallel spaces, said duct having open ends for connection with any one of a variety of connectors or caps.

13. A connector for use in a cable duct installation in a concrete floor slab capable upon installation of assuming a number of modes, comprising, prior to installation, a longitudinally extending trough portion defined by a floor and a pair of opposed sides, said sides having connection means on the top edge thereof to facilitate the connection of a cover plate, the ends of said trough portion adapted to have ducts connected thereto, and each opposed side of said trough portion including perforations therein, which facilitate the creation of an opening in the side by folding down a floor portion of the side and folding outward a pair of wall portions, which together define a further opening for connection of a further duct.

14. A blank for a connector for use in a cable duct installation, wherein said blank comprises a generally rectangular web having a pair of parallel score lines there across parallel with a pair of edges of said web, each score line associated with a said edge, and spaced equidistantly therefrom, said spacing defining the intended height of said connector, said parallel score lines being separated by a distance substantially the same as the width of a cable dust of the installation, and for each *999 said score line and associated edge, a pair of potential fold lines, being scored or S "perforated and extending perpendicularly from each score line to its associated edge, S" 20 said pair separated by substantially the width of a said duct, a pair of potential vertical cut lines, being cuts, or broken cuts, extending perpendicularly between said score line and said associated edge, and located between said pair of potential fold lines, and a pair or potential horizontal cuts, being either cuts or broken cuts, each extending along said score line, from the point where one of said potential folds meets said score line to the point where the adjacent said potential vertical cut meets said score line.

15. A connector for use in a cable duct installation formed from a blank as claimed in claim 14 wherein by folding up the regions between each score line and its associated side along each said score line to thereby form a longitudinal trough, where a flanged opening may be achieved in each or either side wall by forming the appropriate potential cuts (if not already formed), folding out a pair of vertical -16- flanges about the potential fold lines, and folding down any remaining section of the wall between said flanges.

16. A joint between two or more cable ducts as claimed in claim 12 and incorporating a connector as claimed in either claim 13 or claim 15 wherein a pair of said cable ducts extend into said trough through the ends thereof, and one or more ducts are engaged with said formed openings, at least between said formed flanges, said ducts being as described in the above paragraph, and having a said upstanding dividing wall running longitudinally there through, there being a horizontal separating plate in said trough of said connector, having a slot at each end thereof extending into said plate in the longitudinal direction of said ducts, said slots in registration with said upstanding dividing walls, and being disposed about the ends thereof.

17. A cable duct system including an adjustable support trough as claimed in either claim 1 or claim 11.

18. A cable duct system including a length of cable duct as claimed in claim 12

19. A cable duct system including a connector as claimed in either claim 13 or claim

20. A cable duct system including ajoint as claimed in claim 16

21. A blank for a support frame substantially as herein described with reference 20 to and as illustrated by Figures 2 to 4 of the accompanying drawings.

22. A cable duct system substantially as herein described with reference to and as illustrated by the accompanying drawings.

23. A method of installation of a cable ducting system substantially as herein described with reference to and as illustrated by the accompanying drawings. °•oo oS