GB2441412A

GB2441412A - T junction for cable trunking.

Info

Publication number: GB2441412A
Application number: GB0715792A
Authority: GB
Inventors: Boris Daniel Romero
Original assignee: Rehau Ltd
Current assignee: Rehau Ltd
Priority date: 2006-09-01
Filing date: 2007-08-14
Publication date: 2008-03-05
Anticipated expiration: 2027-08-14
Also published as: GB0715792D0; GB2441412B; GB0617168D0

Abstract

A T-piece fitting for joining three lengths of cable trunking of the type having spaced compartments for cable has three joining zones 34,35,36 for joining with the respective lengths of cable trunking. Each of the zones 34,35,36 has two ports respectively positioned to align with respective chambers of the trunking, at least two cable crossing chambers 51,52,53,54 within the fitting, passages within the fitting each leading from a respective port to the cable crossing chambers 51,52,53,54 and at least one spacer member which has means for fitting in one of the cable crossing chambers (51,52,53,54) to separate cables crossing the chamber from different passages.

Description

-I-

FITTINGS FOR CABLE TRUNKING

This invention relates to cable trunking of the type used for distributing mains and/or data cable around buildings and, in particular, to certain fittings for such trunking.

The type of trunking with which the invention is particularly, but not exclusively, concerned is the type intended to house both power (mains) and data cabling. Current European standards for telecommunication installations specify a certain minimum distance between the power and the data cables in such trunking in order to reduce electromagnetic interference between the two. The specified distance depends upon the level of electromagnetic screening provided by the trunking and type of cable: for example, if there is no screening the minimum distance is specified as 200mm; if a steel shield is in place, the distance can be reduced to 50mm. The standards also refer to a minimum bend radius for cables carrying data, in order to prevent damage to the cables as they are routed around corners.

In addition to their role in guiding cabling around buildings, cable trunking is often designed in such a way as to enable sockets to be conveniently fitted to provide mains and data outlets. The European standards permit wiring to sockets and similar outlets to come closer than the normal recommended minimum distances, because such outlets are only intermittently spaced along the trunking and therefore do not significantly degrade the electromagnetic isolation between the mains and data cables. Furthermore, under current UK wiring regulations, mains and data cables are required to be separated by a non-conductive partition.

The result of the standards and regulations has been that a particular profile of cable trunking has become common in the industry.

This comprises some variation of a profile essentially comprising three compartments: an upper compartment, a lower compartment and an intermediate compartment. The upper and lower compartments house either mains cable exclusively, or data cable exclusively and the intermediate compartment essentially defines the space between them, as required by the standards. In practice the data cables are usually housed in the lower compartment and the power cables in the upper compartment.

Any outlets are generally positioned in the intermediate compartment, and any wiring to these outlets is thus confined to short lengths from the adjacent upper or lower compartment, as appropriate.

Figures 1 and 2 of the accompanying drawings show, in diagrammatic form, two styles of trunking profile in current use. The trunking is generally fabricated by extrusion from plastics material such as rigid PVC, ABS, polypropylene, high-density polyethylene, but may also be fabricated from other materials such as metal.

Referring to Figure 1, the profile comprises a backplate 1 which is secured to a wall or similar surface by screws or similar.

Removably secured to the backplate is a cover 2 which is shaped to define a generally rectangular interior which is divided by horizontal partitions 3 and 4 into an upper compartment 5, an intermediate compartment 6 and a lower compartment 7.

The manner in which the various illustrated components are configured and attached together varies from manufacturer to manufacturer and Figure 1 does not show the detail of any interconnections. The cover 2 in particular can be realised in a number of different ways and will in practice not normally be formed as a single part, but as two or more parts which are fitted to create a profile somewhat as shown.

If electromagnetic shielding is to be provided, this will normally be by way of a strip of steel or aluminium fitted against one or both of the partitions to screen the upper and lower compartments 5, 7 from each other. The use of electromagnetic shielding enables the distance between the power and data cables to be reduced, and this in turn allows the height of the intermediate compartment to be reduced.

In normal usage, the upper compartment 5 is used for power cable and the lower compartment 7 for data cable (not shown). Any outlets which are to be fitted will generally be installed on that part 8 of the cover 2 which overlies the intermediate compartment 6. Wiring to such outlets extends to the intermediate compartment from the adjacent upper or lower compartments, as appropriate through pre-installed knockouts or holes drilled on site in the partitions 3 or 4.

In the alternative style of profile illustrated in Figure 2 the upper partition 3 is formed as a shelf 9 extending from the backplate I and having an upturned distal edge 10 which enables a bundle of power cables to be securely held a safe distance away from the data cables in the lower compartment 7. In the profile of Figure 1, provided that sufficient electromagnetic screening is in place, the height of the intermediate compartment can be reduced to a level at which difficulty can be experienced in physically fitting outlets, particularly power outlets. The arrangement illustrated in Figure 2 enables such outlets to extend partially into the upper compartment and thus enables the overall height of the profile to be reduced, giving a more compact appearance.

The manufacturers of cable trunking generally also provide various types of fitting, specifically matched to the trunking profile, for taking the cable round corners and other obstacles, or simply for changing the direction of the trunking. The present invention is particularly concerned with fittings which allow a change of direction (usually by 90 ) of the trunking whilst remaining on the same surface, as distinct from fittings which allow the cable to be taken around an internal or external wall corner.

Such fittings may comprise T-pieces, allowing for a branch to be formed off a length of trunking, or corners, allowing for a change of direction of the trunking.

Figure 3 of the accompanying drawings is a diagrammatic plan view of a generic T-piece fitting for use with cable trun king of the type illustrated in Figures 1 or 2. The 1-piece includes three interface zones 20, 21 and 22 at each of which the fitting interfaces with the cut end of a length of cable trunking (not shown). The cables passing from the trunking into the fitting emerge from one of the upper or lower compartments of the trunking and are thus spaced from one another according to which compartment they have emerged from.

Figure 3 is simplified so as to illustrate all the possible combinations of routes for cable passing from the upper or lower compartment of the three lengths of trunking being joined by the 1-piece fitting. There are 12 possible routes, and 10 of these, numbered ito 10, are illustrated in Figure 3. The fitting itself is illustrated in outline form under the reference 12.

Thus, as an example, routes 1, 2 and 3 are for cable, probably power cable, entering the fitting from a length of trunking (not shown) to the left. Cable entering to the left may exit to the left-hand compartment of vertical trunking (route 1), to the right-hand compartment of vertical trunking (route 3), to the lower compartment of trunking on the right (route 2) or to the upper compartment of trunking on the right. To avoid complicating the drawing too much, the "straight through" routes from left to right have been omitted.

To allow complete flexibility during installation, it is clearly desirable that the fitting is able to cater for all these possibilities whilst at the same time ensuring that the power and data cables are kept separate, as specified by the current European standards and UK wiring regulations.

WO 2006/064206 describes a T-piece fitting for joining lengths of cable trunking in which this problem of cable separation is addressed by providing a bridge component which is rotatable between various positions to provide different routings for cable passing through the fitting. Unfortunately the rotatable bridge component is a complicated item and is relatively expensive to produce and, furthermore, only allows for a limited number of cable routes through the fitting.

In a first aspect of the present invention there is provided a T-piece fitting for joining three lengths of cable trunking of the type having spaced compartments for cable, said fitting comprising three interface zones for interfacing with the respective lengths of cable trunking, each of said interface zones having two ports respectively positioned to align with respective compartments of said trunking, at least two cable crossing chambers within said fitting, passages within said fitting, each leading from a respective port to said cable crossing chambers and at least one spacer member the or each of which has means for fitting in one of said cable crossing chambers to separate cables crossing the chamber from different passages.

Conventionally, T-piece fittings are fabricated in two parts: a base part which is screwed or otherwise affixed to a wall or other surface, and a cover part which covers the base part thus protecting the cables and providing an aesthetically pleasing transition between the lengths of trunking. The base part thus defines with the cover part a hollow interior in which the cables are routed as required from one length of trunking to another.

In the preferred embodiment of the present invention, this mode of construction is adopted, with the base part being provided with formations which act together to define the aforesaid passages and chambers. During installation, and before the cover is fitted, the passages and chambers are open to allow fitting of cables and one or more spacer members. Fitting of the cover part closes off the passages and chambers.

Preferably the base part comprises a base plate on which said formations are mounted so as to define walls which, together with the base plate, form said passages and chambers. In order to avoid excessive bending of the cables, it is preferred that, in the area of the chambers, where the cables may be turning a corner, the walls are curved with a suitable minimum radius of curvature, in order to meet the standards.

For greatest efficiency in the positioning of cables, it is preferred that each of the chambers is positioned so as to be aligned with at least one port from all three of the interface zones. In the preferred embodiment, the chambers are positioned as follows: A first chamber is aligned with a first port from each of the interface zones.

A second chamber is aligned with the said first port from two of the interface zones and a second port from the third interface zone.

The conventional T-piece fitting is intended for the branching off at an angle of 90 of a length of cable trunking from a straight run of cable trunking. In this case the two interface zones which interface with the ends of the trunking in the straight run are essentially aligned in parallel with one another, whilst the interface zone which interfaces with the branch length of trunking is at right angles to the other two interface zones -see Figure 3.

In such a fitting, two further chambers may be provided, as follows: A third chamber is aligned with the said second port from said two of the interface zones and a first port from the third interface zone.

A fourth chamber is aligned with the said second port from said two of the interface zones, and the second port from the third interface zone.

The third and fourth chambers are primarily intended as areas in which the cables can be guided round a corner, and would not normally be used for cable crossover. However, in certain circumstances, these chambers can be used for cable crossovers, in which case the chamber walls may be fitted with means for mounting a spacer member to separate data and power cables. However, it is believed that all possible combinations of routes can be realised by providing for cable crossover only in the first and second chambers.

The spacer members may simply comprise sheets of suitable material, for example metal or plastics material, which are shaped to enable them to be placed into a respective chamber. Each chamber is provided with means to locate the spacer member at an intermediate position within the chamber, such as to divide the chamber into two sub-chambers each of which can carry either data or power cables, but not both. In this way, both data and power cables can pass through the chamber whilst remaining separate from one another because, as they cross, they are spaced from one another at least by the thickness of the spacer member. Various ways of suitably locating the spacer member within the chamber can be conceived, and one way will be described below.

In the preferred embodiment, the first and second chambers are immediately adjacent one another and in fact run into one another.

With certain routings of cable, it is found that the crossover of the data and power cables occurs part in the first chamber and part in the second. In this event, it may be necessary to use two spacer members, one fitted in each of the first and second chambers to provide a continuous, or at least near-continuous, spacer member across the two chambers.

It would also be possible to fabricate a "double size" spacer member which is such that it fits in two chambers simultaneously to provide the aforesaid continuous spacer member across the two chambers. Such a spacer member may be provided with a scored or otherwise weakened central portion which may be broken to create two single-chamber spacer members.

As mentioned, the spacer members may simply comprise a sheet of material, suitably shaped to fit in the chambers. These can be cheaply fabricated by punching from a larger sheet of material. However, more sophisticated spacer members can be fabricated, albeit at greater cost, if further functionality is required. For example, the spacer member could be provided with upstanding wings to provide a cable guidance function; however, this may limit the cable routing options. Also, it will be understood that the spacer members could be perforated in order to save on material.

Figure 4 of the accompanying drawings is a diagrammatic plan view of a short section of cable trun king 20 and two corner fittings 21, 22. The drawing is intended to illustrate a problem which arises particularly with asymmetric trunking profiles, that is, profiles such as shown in Figure 2, which are not symmetric about their mid-horizontal axis and can thus only be used in a single orientation. It will be noted that the trunking of Figure 1 is symmetric and can thus be used either way up.

In order to simplify Figure 4, only one of the partitions, namely partition 3, defining the lower compartment 7 carrying the data cables, is shown. The corner fittings 21, 22 are provided with partitions to separate the power and data cables as they pass around the corner. These partitions are positioned to match the partitions 3 and 4 in the cable trunking to be joined. Only one of the partitions 2, shown under reference 23, is illustrated.

In Figure 4A, it will be noted that the corner fittings 21, 22 are identical in design. Because of this, the fitting can only be matched to the trunking if it turns downwards, as in the case of fitting 22 on the right hand side. In the case of the left hand side fitting 21, it will be seen that the partition 3 carrying the data cables within the trunking does not match with the corresponding partition 23 in the fitting. In order to cater for this, as illustrated in Figure 4B, a different design of the left hand fitting 21 must be used. This means that, to provide for both left and right handed corners, particularly for asymmetric trunking, two designs of fitting have to be offered.

In a second aspect, the present invention seeks to provide a corner fitting which can be adapted for use for both left and right hand corners, and which can be used both with symmetric and asymmetric trunking profiles.

According to the second aspect of the invention there is provided a corner fitting for cable trunking, said fitting comprising a base part for attachment to a wall or other surface and a cover part for attaching over the base part to cover same and to provide a hollow interior for the passage of cable, said fitting being characterised by a cable guide member, and wherein said base part has first and second spaced attachment means for attaching said guide member within the interior at one of two spaced positions in order to guide cable round the corner.

Preferably said attachment means are positioned and designed in such a way as to additionally provide a cable guidance function in their own right. Thus each of the two attachment means are positioned on the base part in such a way as to guide cables emerging from a respective compartment within one length of trunking around the corner to the corresponding compartment within the other length of trunking, whilst at the same time maintaining separation between them and maintaining an appropriate minimum bend radius.

It has already, been mentioned that one of the compartments may contain data cables whilst the other contains power cables. The cable guidance function of the attachment means can be positioned to provide the necessary separation between the data and power cables, but physical limitations mean that they will not necessarily be able to provide the necessary minimum radius of curvature as the cable passes round the corner. However the European standards for minimum radius of curvature apply only to data cable. Therefore, in the preferred embodiment, the cable guide member is such as to define a curved surface having a radius of curvature sufficient to provide a smooth path for data cable round the -10-corner. Preferably the radius of curvature is such as to meet any minimum radius of curvature which is specified by any standards which are in force.

Thus, the cable guide member may be fitted to the base part by whichever of the two attachment means will position it suitably for guiding the data cable from the adjacent trunking around the corner.

Meanwhile, the power cable may be guided around the other of the two attachment means, which is not fitted with the cable guide member, and will thus not have the benefit of being guided around a slow curve.

In this way separation of data and power cables is maintained while at the same time providing a cable guide which ensures a minimum bend radius for the data cable. As will be understood, the cable guide member can be fitted to either one of the attachment means, according to the relative positions of the data and power cables within the adjacent trunking, and thus both left and right hand corners can be catered for with the same set of components.

In the preferred embodiment each attachment means comprises one or more posts which extend from the base part in order to position and support the cable guide member. If the cable guide member is not fitted, the post or posts themselves are sufficient to provide a cable guidance function, albeit with a rather low radius of curvature. Preferably the post or posts are provided with one or more formations which locate with correspondingly shaped formations in the cable guide member. For example, the or each post may be provided with a peg which is positioned to enter a corresponding hole in the cable guide member to locate the two together.

Each attachment means may also include similarly cooperating formations as between the base parts and the cable guide member. For example, the cable guide member may be provided with a peg or pegs, the or each of which locate in a hole or slot in the base plate.

For ease of fitting the cable guide member, the or each hole in the base -11 -part may be associated with a guide groove having a funnel shape with a sloping base acting to guide the peg or pegs on the cable guide member into the respective hole or holes in the base part.

It has been mentioned that the first and second attachment means are positioned on the base part to guide cables respectively emerging from one or the other of the two cable-carrying compartments of the adjacent trunking. In the case of a 900 corner (the most common design), an axis can be defined through the base part which bisects the corner, and is thus at an angle of 450 with respect to each of the lengths of trunking which are connected by the fitting. In the preferred embodiment, the two attachment means are positioned at spaced radial positions along this axis so that the base part, and indeed the whole corner fitting, is substantially symmetric about this axis.

In a further aspect of the invention there is provided a fitting for cable trunking, said fitting designed for use either as a corner fitting or a 1-piece, said fitting comprising a base part for attachment to a wall or other surface and a cover part for attaching over the base part to cover same and to provide a hollow interior for the passage of cable, said fitting having a cable guide member, and wherein said base part has first and second spaced attachment means for attaching said guide member within the interior at one of two spaced positions in order to guide cable either round the corner or at a T-junction located along a straight length of trunking.

In one embodiment each attachment means comprises a latch arrangement disposed around each of two holes formed in the base part.

In a preferred embodiment the guide member comprises a base having upstanding curved walls along its edges, the walls and base defining together curved guide channels along which cables can be supported and guided, and the channels may lead to three interface zones for interfacing with the respective lengths of cable trunking, -12-In order that the invention may be better understood, several embodiments thereof will now be described by way of example only and with reference to the accompanying drawings in which: Figures 1 and 2 are diagrammatic representations of two known cable trunking profiles; Figure 3 is a diagrammatic representation of a T-piece fitting showing cable routings; Figure 4 is a diagrammatic representation of a trunking system comprising two corner fittings and a length of cable trunking; Figures 5 and 6 are respectively side elevation and plan views of the base part of a 1-piece fitting according to an embodiment of the first aspect of the invention; Figure 7 is a perspective view from above of the base part of Figures 5 and 6; Figure 8 is a perspective view from below of the base part of Figures 5 and 6; Figure 9 is a perspective view from above of a spacer member for use with the base part of Figures 5 and 6; Figures 1 OA to D are four plan views of the base part of Figures 5 and 6, showing four alternative positions for the spacer member of Figure 9; Figure 11 is a perspective view from above of the base part of Figures 5 and 6 fitted with the spacer member of Figure 9; Figure 12 is a perspective view of an alternative design of spacer member for use with the base part of Figures 5 and 6; Figures 13 and 14 are respectively plan and perspective views of the base part of Figures 5 and 6, slightly modified, showing the spacer member of Figure 12 fitted thereto; Figures 15 and 16 are perspective views, respectively from above and below, of a cover part to fit over the base part of Figures 5 and -13 -13; Figure 17 is a perspective view from above the base part of a corner fitting according to one embodiment of the second aspect of the invention; Figure 18 is a view of part of Figure 17 on an enlarged scale, showing one of the attachment means; Figure 19 is a perspective view from above of a cable guide member for use with the base part of Figure 17; Figure 20 is a view similar to Figure 19, but showing the method of attaching its cable guide member to the base part; Figure 21 is a diagrammatic plan view of a trunking system comprising two corner fittings according to the second aspect of the invention joining three lengths of trunking; Figures 22 and 23 are perspective views, respectively from above and below, of a cover part to fit over the base part of Figure 17.

Figure 24 is a perspective view from above the base part of a corner and 1-piece fitting according to a further embodiment of the invention; Figure 25 is a perspective view from above of a cable guide member for use with the base part of Figure 24; Figures 26 and 27 are perspective views of two types of cover part to fit over the base part of Figure 24; Figure 28 are diagrammatic plan views of various trunking systems, the flat angle system comprising two corner fittings each with left and right hand options and the T-piece system comprising one T-piece, the corner and T-piece fitting being according to the further embodiment of the invention and Figures 29 to 32 are exploded views of corner and T-piece fittings in accordance with the second embodiment illustrating the cable guide member in different orientations relative to the base part.

-14 -There will now be described a first embodiment of a T-piece fitting for cable trunking in accordance with the first aspect of the present invention.

The fitting comprises a base part 30, shown in Figures 5 to 8, a spacer member 31, shown in Figure 9, and a cover part 32, shown in Figures 15 and 16.

Referring to Figures 5 to 8, the base part 30 comprises a base plate 33 on which is formed a number of formations in the form of straight and curved walls which define passages and chambers within the fitting, as will be explained.

The base plate has a generally rectangular shape with edges to 43, and has a straight wall 38, upstanding vertically therefrom, along its edge 43. Each of the edges 40 to 42 is formed with a pair of upstanding pegs 39 which locate into corresponding holes in the cut end of a length of cable trunking (not shown), for example of the type illustrated with reference to Figures 1 or 2. During installation, the ends of the trunking are located over the pegs 39 and are butted up to the respective edge 40, 41 or 42. Thus the junction between each of the edges 40, 41 or 42 and its respective length of trunking forms an interface between the trunking and the fitting, and each edge 40, 41, 42 and the adjacent edges of the walls therefore together constitute a respective "interface zone" 34, 35 or 36.

A plurality of countersunk fixing holes 44 are formed in the base plate to allow the filling to be fixed to a wall or similar surface by means of screws or other suitable fixings.

In addition to the straight wall 38, the base plate 33 also has a number of curved walls 45 to 50 upstanding vertically therefrom. The base plate walls together define four chambers 51 to 54 and passages 55 to 60 which lead from the chambers to one of the interface zones 34 to 36. Thus the various passages may be described as follows: 1) Passage 55, defined by walls 38 and 45, extends -15-between interface zone 34 and chamber 51; 2) Passage 56, defined by walls 45 and 46, extends between interface zone 34 and chamber 52; 3) Passage 57, defined by walls 46 and 47, extends between interface zone 35 and chamber 52; Passage 58, defined by walls 47 and 48, extends between interface zone 35 and chamber 53; 5) Passage 59, defined by walls 48 and 49, extends between interface zone 36 and chamber 53; and 6) Passage 60, defined by walls 38 and 49, extends between interface zone 36 and chamber 54.

At each interface zone 34, 35 or 36, the walls are positioned such that the entrance ports to each of the passages is in approximate alignment with a cable carrying compartment 5 or 7 of the adjacent length of trunking.

Thus, for example, data cable from compartment 7 might pass into passage 55 via interface zone 34 and pass to chamber 51. At this point,the cable may proceed as follows: 1) Straight on, via chamber 54 and passage 60, exiting the fitting via interface zone 36 into one of the compartments of the trunking adjacent interface zone 36.

2) Turn through 90 in chamber 51, and pass through chamber 52 and passage 57 into one of the compartments of the trunking adjacent interface zone 35. Note that the minimum bend radius of the cable in its passage round the corner is dictated by that of the curved wall which can thus be set to meet European standards for telecommunication installations and UK wiring regulations.

3) Straight on to chamber 54, then turn through 90 and pass through chamber 53 and passage 58 into the other of the compartments of the trunking adjacent interface zone 35. Note that the -16-minimum bend radius of the cable in its passage round the corner is dictated by that of the curved wall 50.

4) Turn through 900 in chamber 51, and pass into chamber 52 where the cables turns again through 90 into chamber 53, and exits the fitting via passage 59 into the other of the compartments in the trunking adjacent interface zone 36.

The above are the four principal routes for cable entering at passage 55 and proceeding through the fitting. Other routes within the fitting will be apparent, but will not achieve anything beyond the four principal routes described above.

We will now briefly consider the four principal routes for power cable entering the fitting via interface zone 34 at passage 56. This may proceed as follows: 1) Chamber 52, chamber 53 passage 59 and exiting via interface zone 36; 2) Turning at chamber 52 to passage 57, and exiting via interface zone 35; 3) Chamber 52, turning at chamber 53 to passage 58, and exiting via interface zone 35; and 4) Chamber 52, turning at chamber 53 into chamber 54, turning in chamber 54 to passage 60, and exiting via interface zone 36.

Similar cable routes through the fittings will be apparent for cable entering through the interface zones 35 and 36, but will not be described in detail. However, it will be apparent that all of the combinations described above with reference to Figure 3 can be realised.

It will be apparent that, whichever combination of cable routings are used, at least one crossover of data and power cables will occur. Because of the arrangement of the passages and chambers, crossovers will always occur within one or more of the chambers, or between two chambers. Therefore provision needs to be made, in at least -17-those chambers where there are crossovers, for separating the data and power cables. A suitable spacer member for this purpose is illustrated in Figure 9. The spacer member 31 comprises a flat support portion 61 over which cable (not shown) may be laid and a pair of upstanding wings 62 which prevent lateral displacement of the cable. At each corner is provided a guide lug 63 which is slidable in a corresponding slot 64, formed in the walls 38 and 45 to 49. These slots can be clearly seen in Figure 7. The slots extend vertically downwards from the distal edges of the walls and are open at the distal edge to allow a corresponding guide lug 63 to enter.

The slots extend downwards only a part of the height of the walls, the arrangement being such that the lugs can pass only down to the bottom of the slot. The length of the slots is such that, when the lugs 63 are located at the bottom of the slots, the cable support portion 61 of the spacer member 31 is positioned approximately mid-way down the chamber concerned, thus effectively splitting the chamber into two sub-chambers, one for carrying data cable and one for carrying power cable. In this way the data and power cables are separated by at least the thickness of the support portion 61 as they cross over each other. It does not matter whether it is the data cables which cross the spacer member, with the power cables beneath, or vice versa. The particular arrangement will usually be dictated according to the greatest convenience during cable installation.

The manner in which the spacer member 31 fits into the various chambers is clarified in Figure 10. Each part A, B, C and D of Figure 10 comprises a view of the base part similar to Figure 6, but fitted with a single spacer member 31. It will be seen that the disposition of slots 64 is such that the lug 63 in each corner of the spacer member slides down a respective slot so that the spacer member is positioned across one of the chambers 52 or 53. The slots 64 are positioned and arranged to provide for the four possible positions illustrated in Figures 10 A to D. A further -18-possibility is a combination of Figures 1OA and lOB in which a spacer member 31 is fitted in both of chambers 52 and 53 in order to cater for the situation where the cables cross in the interface area between the chambers 52 and 53 (see Figure 11).

It will be noted that slots 64 are also provided to enable the spacer member 31 to be fitted across one or both of chambers 51 and 54.

However, as mentioned above, it is possible to cater for all possible cable routings without resorting to crossovers in chambers 51 and 54 and therefore the facility to allow fitting of the spacer member in these chambers is probably not necessary.

There will now be described with reference to Figures 12 to 14 a second embodiment of a T-piece fitting in accordance with the first aspect of the invention.

In this second embodiment, the same base plate 33 is used, as will be clear from Figures 13 and 14, and detailed description will accordingly be omitted. However, one small difference will be noted, which is that the slots 64 for receiving the spacer member 31 are only provided for the chambers 52 and 53, and not for the chambers 51 and 54. It has already been mentioned that all possible cable routings can be provided for by utilising only chambers 52 and 53 for cable crossovers. This enables a simpler and more versatile design of spacer member 31 to be used, and such a design is shown in Figure 12. This design is formed, for example by punching, from a sheet of suitable metal or plastics material. The shape in plan roughly corresponds to the shape of each of the chambers 52 and 53, having a central cable support section 75 and four "arms" 70 to 73 which each extend either towards the adjacent chambers or towards the passages leading to the interface zones. The wings 62 of the previous embodiment are not necessary because the whole area of the chamber 52 or 53 is filled by the spacer member so cable cannot spill over the edges of the support. The absence of the wings 62 gives greater flexibility in the -19-routing of cables in the upper sub-chamber, and in fact enables all possible cable routings to be realised.

The ends of the arms 70 to 73 are provided with guide lugs 74 which have the same function as the guide lugs in the previous embodiment. The spacer member of Figure 12 can be fitted either in chamber 52, as shown in Figure 13, or in chamber 53, as shown in Figure 14, depending upon the arrangement of cabling. Where a cable crossover occurs in the area between the two chambers 52 and 53, two spacer members of the type shown in Figure 12 can be fitted, one in the chamber 52, and one in the chamber 53.

Although the spacer member 31 illustrated in Figure 12 has a symmetrical shape, it could in fact be handed in such a way that it could be fitted only in a particular orientation without affecting its cable routing capabilities.

Reference is now made to Figures 15 and 16 which show a cover part 32 for the embodiments of Figures 5 to 11 and 12 to 14. The cover part is dimensioned and shaped to closely fit over the base part 30, and protruding latches 76 with a sloping face 77 are formed on the inside surface (see Figure 16)to engage in and latch into corresponding apertures 78 formed in the walls 38, 46 and 48 of the base part 30. By this means, the cover part 32 can be securely latched in position, in such a way as to slightly overlap the ends of the three lengths of trunking being joined and thus create an aesthetically pleasing link between them.

There will now be described an embodiment of a corner fitting for cable trunking in accordance with the second aspect of the present invention.

The fitting, which is intended to join together two lengths of cable trunking at a right angle, comprises a base part 80, shown in Figures 17 and 18, a cable guide member 81, shown in Figure 19 and a cover part 82, shown in Figures 22 and 23.

-20 -Referring to Figures 17 and 18, the base part 80 comprises a base plate 83 having an approximately square shape in which the corner formed by two of the edges 84, 85 is rounded for aesthetic purposes. An upstanding wall 86 is formed along these edges 84, 85, and around the corner. Countersunk holes 87 are formed in the base plate 83 for allowing the fixing of the fitting to a wall or other surface by means of screws or equivalent fixing means.

The other two edges 88, 89 meet at the inner corner 90 of the square. In use, the edges 88 and 89 are located against the cut end of a respective length of trunking (not shown) and upstanding pegs 91 are formed on each edge 88, 89 which pegs locate into corresponding holes in the cut ends of trunking.

Provided on the base plate 83 are two attachment means 92, 93 which act to locate and secure the cable guide member 81. The attachment means are spaced apart along a diagonal axis 94 extending from the corner 90 through the intersection point of edges 84, 85. This axis 94 lies at approximately 45 to each of the edges 88, 89 of the base plate.

It is envisaged that one guide member 81 will be provided with each base part 80, and this can be secured either by the inner attachment means 92 or the outer attachment means 93, depending upon the arrangement of cables within the trunking being joined. This will be explained in more detail below.

Referring to Figure 19, it will be seen that the cable guide member 81 comprises an arcuate sheet of material defining a wall presenting a curved cable guide surface 95. Conveniently, the wall, and hence the surface 95, is bent into an approximately circular arc. Formed through the wall are four holes 96 to 99 which locate in respective pegs attached to the base plate, as will be explained. The bottom edge of the wall is formed with a pair of lugs 100 which locate in holes in the base plate, as will be explained.

-21 -The attachment means 92, 93 are of similar construction, shown in enlarged detail in Figure 18, and are positioned symmetrically about the axis 94. Each attachment means comprises a pair of upstands 101 extending upwards from the base plate 83. At the distal end of each upstand 101 is a peg 102 which faces outwards -i.e. towards the wall 86 -and is intended to engage the holes 97, 98 in the cable guide member 82.

Each attachment means further comprises a pair of holes 103 formed in the base plate 83. These holes are intended to engage respective lugs 100 on the cable guide member. It is intended that the engagement of the pegs 102 in the holes 97, 98 and the lugs 100 in the holes 103 will securely locate the cable guide member 82 on the base plate 83.

In order to assist the process of fitting the cable guide member, each hole 103 is provided with a funnel-shaped guide slot 104 having a sloping bottom surface 105. The method of fitting the guide member is first to engage the pegs 102 into the holes 97, 98 whilst at the same time tilting the guide member slightly to allow this, and then pivoting the guide member upright in such a way that the lugs 100 move down the guide slots 104 at the end of which they snap into the holes 103. Figure 20 shows the cable guide member 32 mounted on the base plate 83.

The base plate 83 is provided with a further pair of upstands 106 and pegs 107 which engage with holes 96 and 99 for providing extra support to the ends of the cable guide member, when fitted in its outer position by attachment means 93. Similar support is provided when the cable guide member is fitted in its inner position (attachment means 92) by engagement with the walls of the adjacent trun king, as will be clear from Figure 21.

Reference is now made to Figure 21 which illustrates a cable trunking system comprising three lengths 110, 111 and 112 of cable trun king, for example of the type previously described with reference to -22 -Figures 1 and 2, joined by two corner fittings 113 and 114 of the type just described.

The corner fittings 113 and 114 are identical, save that the cable guide member 32 is fitted to the outer attachment means 93 in fitting 113 and the inner attachment means 92 in fitting 114. The purpose of this is to cater for the particular arrangement of cabling.

The lengths of trunking are shown as having just two compartments, a first compartment 115 for data cable and a second, larger, compartment 116 for power cable, separated by a partition 117. In practice it is likely that the larger compartment will itself be divided by a partition to create a space between the power and data cables, as in the examples given in Figures 1 and 2. It will be noted that, like the trunking of Figure 2, that shown in Figure 21 is asymmetric and therefore the same problem arises as described above in relation to Figure 4.

As will be seen in Figure 21, the different positioning of the cable guide member as between the fittings 113 and 114 ensures that, at each passage round the two corners, the cable guide member 32 is able to ensure that the data cable is subject to a minimum bend radius which meets the European standards for telecommunication installation and the UK wiring regulations. The power cable, in passing through the fittings, can be guided round the upstands 101 of that attachment means 92 or 93 which does not have the cable guide fitted. Any separation between the data and power cables can thus be maintained through the fitting.

Reference is now made to Figures 22 and 23 which show a cover part 82 for the corner fitting. The cover part is dimensioned and shaped to closely fit over the base part 30, and protruding latches 118 with a sloping face 119 are formed on the inside surface (see Figure 23) to engage in and latch into corresponding apertures 120 formed in the wall 86 of the base part 80. By this means, the cover part 82 can be securely latched in position, in such a way as to slightly overlap the ends of the two -23 -lengths of trunking being joined, and thus create an aesthetically pleasing link between the two.

There will now be described an embodiment of a fitting, suitable for use as either a corner fitting or as a T-fitting for cable trunking.

The fitting, which is intended to join together two lengths of cable trunking at a right angle, whether as a corner fitting, or as a T-piece for joining three lengths of cable trunking comprises a base part, shown in Figure 24, a cable guide member, shown in Figure 25 and a cover part, shown in Figures 26 and 27.

Referring to Figure 24, the base part comprises a base plate having an approximately square shape. Countersunk holes 139 are formed in the base plate 130 for allowing the fixing of the fitting to a wall or other surface by means of screws or equivalent fixing means.

In use, the edges of the base plate 130 are located against the cut end of a respective length of trunking (not shown) and upstanding pegs 131, 132, 133,134 are formed on each edge, which pegs locate into corresponding holes in the cut ends of the respective lengths of trunking.

The base plate 130 is also provided with lugs 135, 136, 137, 138, each lug disposed half way along respective edges of the base plate 130 for fitting into respective slots (not shown) provided on the cover members to securely attach the cover member over the base plate 130.

Symmetrically disposed around each of the two lower pair of countersunk holes 139 are provided four latches which are designed to slot into respective holes in attachment means 150 of the guide member as illustrated in Figure 25.

The guide member illustrated in Figure 25 is provided with a solid base having upstanding curved walls 147, 148 and 149 along its curved edges. Portions of the wall 149 define with each of the walls 147 and 148, and the base, curved guide channels along which cables can be supported and guided. Two of the channels lead to open ends 145 and -24 - 146, the other ends of the channels opening into a larger common guide channel in the region of the attachment means 150. The walls 147, 148 defining the large channel have their distal ends formed as curved wings which extend beyond the base area, the wings having living hinges 151 providing a degree of movement so the wings can snugly fit around the corner of adjoining trunking thereby providing a suitable curved guide surface for the cable. Any wings extending outside the trunking are conveniently snapped off or bent to fold inside the fitting in order that the cover may fit over the base plate. Likewise any unused alignment pegs (131,132,133,134 in Figure 24) extending outside the trunking will also need to be snapped off so as not to prevent fitment of the cover.

Two types of cover member for the fittings are shown in Figures 26 and 27, The cover member illustrated in Figure 26 is provided with two openings 153, 154 to make it suitable for use as a cover of a corner fitting, and the cover member illustrated in Figure 27 is provided with three openings 157,158 and 159 for use as a cover of a T-piece fitting.

Figure 28 illustrates by way of examples the manner in which the fitting can be used either as a corner fitting or as a T-piece fitting. As will be clear the guide member attachment means 150 is secured to the appropriate latches surrounding the appropriate hole 139 on the base plate 130. In the case of the "flat angle up" arrangement one fitting has its guide member attached to the latches surrounding the left hand lower hole 139 and another fitting has its guide member attached to the latches associated with the right hand lower hole 139, the converse being true for the "flat angIe down" arrangement. In this way cable can be fed from adjoining trunking, via the pair of fittings, through a total of 180 degrees along the connecting channels.

When serving as a 1-piece fitting the guide member is secured to the latches around the lower left hole when serving as the "Tee up" configuration and secured to the same latches when serving as the -25 -"Tee down" configuration, the difference being that the guide member is rotated about its attachment axis by 90 degrees. Each T-fitting when aligned with the appropriate channels feeds the cable through 90 degrees.

The different orientations available to the guide member within the fitting can be seen more clearly in the exploded views shown in Figures 29 to 32. Figures 29 and 30 illustrate the two orientations of the guide member in a corner fitting, the ends 145 and 146 of the channels in the guide member being aligned with a portion of the openings 153 and 154 of the cover. Similarly figures 31 and 32 illustrate the two orientations of the guide member in a T-piece fitting, the ends 145 and 146 of the channels of the guide member being aligned with a portion of the openings 158 and 159 in the cover member, the opening to the larger chamber of the guide member in both instances being aligned with a portion of the opening 157.

All of the fittings described herein can be made in a variety of ways, and from a variety of materials. Generally speaking, the fittings will be made so as to visually match the cable trunking with which they are to be fitted. Thus plastics materials such as rigid PVC, ABS, polypropylene, or high-density polyethylene are likely to be most common, and all these materials enable manufacture of the components by, for example, injection moulding, hot/cold bending, thermoforming, vacuum forming, or layered technologies.

Claims

-26 -

CLAIMS

1. A 1-piece fitting for joining three lengths of cable trunking of the type having spaced compartments for cable, said fitting comprising three interface zones for interfacing with the respective lengths of cable trunking, each of said interface zones having two ports respectively positioned to align with respective compartments of said trunking, at least two cable crossing chambers within said fitting, passages within said fitting, each leading from a respective port to said cable crossing chambers and at least one spacer member the or each of which has means for fitting in one of said cable crossing chambers to separate cables crossing the chamber from different passages.

2. A T-piece fitting as claimed in claim 1 wherein the fitting comprises two parts: a base part for attaching to a wall or other surface, and a cover part for covering the base part, the base part defining with the cover part a hollow interior in which cables can be routed as required from one length of trunking to another.

3. A T-piece fitting as claimed in claim 2 wherein the base part is provided with formations which act together to define the aforesaid passages and chambers and whereby before the cover is fitted, the passages and chambers are open to allow fitting of cables and one or more spacer members.

4. A 1-piece fitting as claimed in claim 3 wherein the base part comprises a base plate on which said formations are mounted so as to define walls which, together with the base plate, form said passages and chambers.

-27 - 5. A T-piece fitting as claimed in claim 4, wherein in the area of the chambers, where the cables may be turning a corner, the walls are curved with a suitable minimum radius of curvature, in order to meet the standards.

6. A 1-piece fitting as claimed in any one of claims 1 to 5, wherein each of the chambers is positioned so as to be aligned with at least one port from all three of the interface zones.

7. A T-fitting as claimed in claim 6, wherein the chambers are positioned as follows: A first chamber is aligned with a first port from each of the interface zones.

A second chamber is aligned with the said first port from two of the interface zones and a second port from the third interface zone.

8. A 1-fitting as claimed in any one of claims 1 to 6, wherein two interface zones which interface with the ends of the trunking in the straight run are essentially aligned in parallel with one another, whilst the interface zone which interfaces with a branch length of trunking is at right angles to the other two interface zones, a third chamber is aligned with the said second port from said two of the interface zones and a first port from the third interface zone.

9. A T-fitting as claimed in claim 8, wherein a fourth chamber is aligned with the said second port from said two of the interface zones, and the second port from the third interface zone.

10. A T-fitting as claimed in claim 9, wherein the third and fourth chambers are designed as areas in which the cables can be guided round -28 -a corner.

ii. A T-fitting as claimed in claim 9, wherein the third and fourth chambers can be used for cable crossovers, the chamber walls being fitted with means for mounting a spacer member to separate data and power cables.

12. A T-fitting as claimed in any one of claims ito 10, wherein cable crossover is only provided in the first and second chambers.

13. AT-fitting as claimed in any one of claims Ito 12, wherein the spacer member or members comprise sheets of suitable material, for example metal or plastics material, which are shaped to enable them to be placed into a respective chamber.

14. A T-fitting as claimed in any one of claims 1 to 13, wherein each chamber is provided with means to locate the spacer member at an intermediate position within the chamber, such as to divide the chamber into two sub-chambers each of which can carry either data or power cables, but not both.

15. A T-fitting as claimed in any one of claims I to 14, wherein the first and second chambers are immediately adjacent one another so as to run into one another.

16. A T-fitting as claimed in any one of claims I to 15, wherein the crossover of the data and power cables occurs part in the first chamber and part in the second.

17. A T-fitting as claimed in claim 16, wherein two spacer -29 -members are provided, one fitted in each of the first and second chambers to provide a continuous, or at least near-continuous, spacer member across the two chambers.

18. A T-fitting as claimed in any one of claims ito 17, wherein there is provided a double size" spacer member which is such that it fits in two chambers simultaneously to provide a continuous spacer member across two chambers.

i9. A T-fitting as claimed in claim 18, wherein said "double-size" spacer member is provided with a scored or otherwise weakened central portion which may be broken to create two single-chamber spacer members.

20. A T-fitting as claimed in any one of claims 1 to 19, wherein the spacer member is provided with upstanding wings to provide a cable guidance function.

21. A T-fitting as claimed in any one of claims 1 to 20, wherein the spacer member or members are perforated.

22. A corner fitting for cable trunking, said fitting comprising a base part for attachment to a wall or other surface and a cover part for attaching over the base part to cover same and to provide a hollow interior for the passage of cable, said fitting being characterised by a cable guide member, and wherein said base part has first and second spaced attachment means for attaching said guide member within the interior at one of two spaced positions in order to guide cable round the corner.

-30 - 23. A corner fitting as claimed in claim 22, wherein said attachment means is positioned and designed in such a way as to additionally provide a cable guidance function in their own right.

24 A corner fitting as claimed in claim 22 or claim 23, wherein the two attachment means are positioned on the base part in such a way as to guide cables emerging from a respective compartment within one length of trunking around the corner to the corresponding compartment within the other length of trunking, whilst at the same time maintaining separation between them and maintaining an appropriate minimum bend radius.

25. A corner fitting as claimed in any one of claims 22 to 24, wherein the cable guide member is such as to define a curved surface having a radius of curvature sufficient to provide a smooth path for data cable round the corner.

26 A corner fitting as claimed in any one of claims 22 to 25, wherein the cable guide member is fitted to the base part by whichever of the two attachment means will position it suitably for guiding the data cable from the adjacent trunking around the corner.

27. A corner fitting as claimed in claim 26, wherein the power cable may be guided around the other of the two attachment means, which is not fitted with the cable guide member, and will thus not have the benefit of being guided around a slow curve.

28. A corner fitting as claimed in any one of claims 22 to27, wherein each attachment means comprises one or more posts which extend from the base part in order to position and support the cable guide -31 -member.

29. A corner fitting as claimed in claim 28, wherein the post or posts are provided with one or more formations which locate with correspondingly shaped formations in the cable guide member.

30. A corner fitting as claimed in claim 29, wherein the or each post may be provided with a peg which is positioned to enter a corresponding hole in the cable guide member to locate the two together.

31. A corner fitting as claimed in any one of claims 22 to 30, wherein the cable guide member is provided with a peg or pegs, the or each of which locate in a hole or slot in the base plate.

32. A corner fitting as claimed in any one of claims 22 to 31, wherein the or each hole in the base part is associated with a guide groove having a funnel shape with a sloping base acting to guide the peg or pegs on the cable guide member into the respective hole or holes in the base part.

33. A corner fitting as claimed in any one of claims 22 to 32, wherein the fitting is a 90 corner fitting, an axis being defined through the base part which bisects the corner, at an angle of 45 with respect to each of the lengths of trunking when connected by the fitting.

34. A corner fitting as claimed in claim 33, wherein the two attachment means are positioned at spaced radial positions along said axis so that the base part, and the whole corner fitting, is substantially symmetric about this axis.

-32 - 35. A fitting for cable trunking, said fitting designed for use either as a corner fitting or a T-piece fitting, said fitting comprising a base part for attachment to a wall or other surface and a cover part for attaching over the base part to cover same and to provide a hollow interior for the passage of cable, said fitting having a cable guide member, and wherein said base part has first and second spaced attachment means for attaching said guide member within the interior at one of two spaced positions in order to guide cable either round the corner or at a T-junction.

36. A fitting as claimed in claim 35, wherein each attachment means comprises a latch arrangement disposed around each of two holes formed in the base part.

37. A fitting as claimed in claim 35 or claim 36, wherein the guide member comprises three upstanding curved walls formed along curved edges of its base, portions of one wall defining with each of the other two walls and the base, curved guide channels along which cables can be supported and guided.

38. A fitting as claimed in claim 37, wherein two of the channels lead to open ends, the other ends of the channels opening into a larger common guide channel in the region of the attachment means.

39. A fitting as claimed in claim 38, wherein said other two walls defining the large channel have their distal ends formed as curved wings which extend beyond the base area, the wings having living hinges providing a degree of movement so the wings can snugly fit around the corner of adjoining trunking thereby providing a suitable curved guide surface for the cable.