GB2439811A

GB2439811A - Corner fitting for cable trunking

Info

Publication number: GB2439811A
Application number: GB0712195A
Authority: GB
Inventors: Boris Daniel Romero
Original assignee: Rehau Ltd
Current assignee: Rehau Ltd
Priority date: 2006-07-03
Filing date: 2007-06-25
Publication date: 2008-01-09
Anticipated expiration: 2027-06-25
Also published as: GB2439811B; GB0712195D0; GB0613073D0

Abstract

The fitting, for either an external corner or an internal corner comprises a base member and a cover member, the base member being adjustable about an axis perpendicular to the direction of cabling to accommodate corners of varying angles about an expected 90 degees. The base member has shelves (82a,82b,84a,84b,86a,86b) for supporting cables around the corner, and the cover member covers the gap between facing ends of associated lengths of the cable trunking. The base member is constructed with a living hinge (87) between two sections to provide the angular adjustment. The cover member is similarly adjustable but by means of pins on one section in apertures of the other section to provide hinging. A cover member for an internal corner is also provided on an interior surface with formations for guiding the cable around the corner.

Description

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 such trunking specify a certain minimum distance between the power and the data cables, when the cables are more than 35 metres in length, 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: for example, if there is no screening the minimum distance is specified as 200mm; if a steel shield is in place, the is distance can be reduced to 50mm.

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.

The result of the standards 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 upper compartment and the power cables in the lower 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 io 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 height of the intermediate compartment to be reduced.

In normal usage, the upper compartment 5 is used for data cable and the lower compartment 7 for power 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 through the intermediate compartment to the adjacent upper or lower compartments, as appropriate through pre-installed knockouts or holes drilled on site in the partitions 3 or 4.

s 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 to 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.

A problem which arises with all styles of cable trunking is how to handle the cable at corners, both internal and external. There is a need to provide for the safe passage of the cables round the corner, ensuring that the cable is not internally damaged by too tight a curvature, and a need to ensure that the cables remain securely housed as they pass around the corner both to ensure safety from accidental contact with the cable, and to provide an aesthetically pleasing bridge between the two open ends of the trunking adjacent the corner. These needs are provided for by internal and external corner fittings, designed to fit each manufacturer's particular trunking profile both externally, for aesthetic effect, and internally, to ensure that the cables are routed efficiently around the corner without damage.

To achieve this it is known to fabricate the corner fitting in two parts: a base member which is roughly functionally equivalent to the base-plate of the trunking profile and a cover member which is roughly functionally equivalent to the cover of the trunking profile. The exact structure of these members varies from manufacturer to manufacturer, both because of the need to match to their own trunking design, and also to provide for any particular features that they may incorporate. However, generally speaking, the base member of the corner fitting will fit against the wall at the corner and will incorporate means for supporting the cable round the corner from one length of trunking to the other. The cover member fits over the base member to cover the gap between the ends of the trunking.

A problem arises during the installation of corner fittings if the two walls or other surfaces which form the corner are not at right angles to io each other. Small errors can be accommodated without difficulty but if the error becomes too great, difficulty can be experienced in attaching the fittings properly at the ends of the trunkirig and in getting the cover member to fit properly, resulting in gaps which are unsightly and are a potential safety risk.

It is known to fabricate the cover member in two sections which are movable -for example, pivoted -with respect to one another to provide an adjustable cover member. However, this is only suitable for quite small angular errors.

To cater for larger angular errors, the present invention provides that the base member of the corner fitting is made adjustable about an axis parallel to the line of intersection of the planes of the two surfaces -usually wall surfaces -that make up the corner.

Thus, according to a first aspect of the present invention there is provided a corner fitting for cable trunking, said corner fitting comprising a base member having cable support means for supporting cable passing from one length of cable trunking to another length of cable trunking round a corner, and a cover member for covering the gap between the ends of said lengths of cable trunking, the corner fitting being characterised in that the base member is angularly adjustable.

It will be understood that the purpose of the angular adjustment is to enable the base member to be fitted into corners formed by surfaces between which the angle is in a range about an expected angle, the latter usually being 90 .

Preferably the base member comprises two sections s separated by a hinge. If the base member is made of plastics material, for example by injection moulding, this hinge can be formed as a living hinge between two otherwise integrally-formed sections. When fitted, the intention is that the axis of the hinge will be parallel to the corner edge -i.e. with the line which forms the intersection of the two surfaces which form the corner.

In a preferred embodiment, the base member comprises a panel having a living hinge extending across it and dividing the panel into a first section and a second section hinged with respect to one another by the living hinge. On each section of the panel is formed at least one shelf for supporting cables as they pass around the corner. To avoid excessive bending of the cable, it is preferred that the shelf or shelves are placed at a height which corresponds to the partition or partitions in the trunking they are intended for. Thus, in the type of trunking described with reference to Figures 1 and 2, there will preferably be two shelves on each section of the panel.

The corresponding shelves on the two panel sections can be positioned at very slightly different heights from each other -insufficient to result in excessive cable bending -so that, as the two panel sections hinge with respect to one another, the shelves can overlap so that they do not collide with one another.

However, since the expected range of adjustment is small, in an alternative embodiment, the corresponding shelves are at the same height, and their facing edges on the two panel sections are angled in the plane of the shelf to allow a small amount of adjustment about a mean position. This mean position will be the position of the hinge at the expected normal angle of the corner (probably 900).

The exact shape of the panel will depend upon whether it is intended for an internal corner fitting or an external corner fitting, and particular examples will be described below.

Preferably the adjustable base member is used in conjunction with a cover member which is also adjustable. As already mentioned, adjustable cover members are already known in the art, but may need adaptation. For example, one particular problem which arises in connection with corner fittings for internal corners is that, unless great care is taken by the installer, current designs of cover member can result in unduly tight bending of the cable, leading to potential internal damage. It is thus desirable to provide means for ensuring a certain minimum radius as the cable is routed around the corner. In the case of external corners, this can be readily achieved by ensuring that the aforesaid panel defines a smooth curve of a predetermined minimum radius of curvature. However, this is not so easy with an internal corner fitting where it is the cover member which essentially dictates the radius of curvature about which the cables are routed and, unless specific steps are taken, this radius of curvature tends to be quite small due to the normal geometry of the internal fitting cover member.

We seek to overcome this problem by providing, in a second aspect of this invention, a cover member for an internal corner cable trunking fitting, said cover member being characterised by having formations protruding from its inside surface which act together for guiding cable around the internal corner at a predetermined minimum bend radius.

Preferably the cover member is of the adjustable type, having two sections pivoted with respect to one another in order to cater for corners formed by surfaces between which the angle is other than expected. In this case the formations may be formed on both sections so as to smoothly route the cables around the corner, whatever the adjustment setting of the fitting.

It was explained above that, in trunking intended to carry both data and power cables, the cables themselves are confined to particular compartments, spaced from one another in order to avoid electromagnetic interference. This means that, in the comer fittings intended for this style of trunking, the cables will likewise be confined to particular areas of the fittings. Thus it is preferred to provide the formations only in those parts of the cover member where cable is expected to be installed.

The formations may take various forms according to the particular shape of the cover member. In the preferred embodiment, the formations take the form of parallel ridges extending from the internal surface of the cover member. The distal edges of these ridges act together to define a predetermined minimum bend radius for cables routed round the internal corner.

is 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; Figures 3 and 4 are respectively front and rear perspective views of the base member of an external corner fitting made in accordance with the invention; Figures 5 and 6 are respectively top and side elevations of the base member illustrated in Figures 3 and 4; Figure 7 is a perspective view of a cover member suitable for use with the base member illustrated in Figures 3 and 4; Figures 8 and 9 are respectively front and side perspective views of the base member of an internal corner fitting made in accordance with the invention; Figures 10 and 11 are respectively top and side elevations of the base member illustrated in Figures 8 and 9; Figures 12 and 13 are respectively front and rear perspective views of a cover member suitable for use with the base member illustrated in Figures 8 and 9; Figure 14 is an enlarged section of part of Figure 13 to show the cable guide ridges in more detail; Figure 15 is a perspective view from above and one side of the cover member of Figures 12 and 13; Figure 16 is a top view of the cover member illustrated in Figures 12 and 13.

Figures 17 and 18 are respectively front and rear perspective views of a base member of an external corner fitting made in accordance with a different embodiment of the invention; Figures 19 and 20 are respectively front and rear perspective views of a base member of an internal corner fitting made in accordance with a different embodiment of the invention; Figure 21 is a perspective view of a further cover member suitable for use with the base member illustrated in Figures 3 and 4; Figure 22 is a perspective views of a further cover member suitable for use with the base member illustrated in Figures 8 and 9; Figure 23 is an enlarged section of part of Figure 22 to show the cable guide ridges in more detail; Figure 24 is a perspective view from above and one side of the cover member of Figures 22; and Figures 25a and 25b illustrate schematically the cross-sectional areas provided by a conventional corner fitting to that of a corner fitting of the present invention.

Referring firstly to Figures 3 to 6, there is shown the base member for an external corner fitting for cable trunking of the type illustrated with reference to Figures 1 and 2.

The base member comprises a panel 11 which is curved about an axis of curvature which, in use, is vertical. Extending from the upper edge of the panel to its lower edge is a line 12 of thinner material which forms a living hinge dividing the panel 11, and indeed the whole base member, into two symmetrically matched sections 13, 14.

Extending from the front-facing surface of the panel 11 are two shelves 15, 16. Each shelf is made of two individual sub-shelves 15a, 15b and 16a, 16b on each side of the living hinge 12, as shown. The upper shelf 15 is designed to be at approximately the same height as the upper partition 3, 9 in the trunking shown in Figures 1 and 2. The lower shelf 16 is designed to be at approximately the same height as the lower partition 4 in the trunking shown in Figures 1 and 2. In this way data and power cable can be supported as it is routed round the corner, and the curvature of the panel ensures that the cable is not subjected to too tight a curve.

The rear surface of the panel 11 is formed with upper and lower ribs 17 and 18 which, like the shelves 15, 16 are each formed as two parts 17a, 17b and 18a, 18b. The purpose of these ribs is twofold: firstly, it will be noticed that the height of the ribs increases the further away from the living hinge they are such that, when they terminate at the respective side edges of the panel, they present a reasonably substantial surface 19 from each of which a peg 20 extends. The purpose of these pegs is to engage in an appropriately positioned slot or hole or other formation in the end of the adjacent trunking profile (not shown), thus securing the base member to the trunking profile. For this purpose, the ends of the trunking profile to be joined by the corner fitting are cut off square and at such a distance from the corner that the edges 21, 22 of the shelves abut up to the cut off ends of the trunking to provide an essentially continuous support for the cable. Four tapering ears 25 are formed as shown on the vertical edges of the panel 11 to cooperate with the pegs 20 in securely joining the corner fitting to the adjacent trunking. The tapering ears 25 also provide more importantly a continuous curved surface for guiding the cable.

The other purpose of nbs 17, 18 is to define a plurality of abutment surfaces 23a, 23b and 24a, 24b which, when pushed over the external corner, will automatically adjust the angle between the two sections 13, 14 to the particular angle of the corner. For this purpose, the base member is constructed so that, when the angle between the surfaces 23a, 23b and 24a, 24b is the normal expected angle (usually 900, as illustrated), the living hinge is set so as to leave a small angle, typically about 50, between the facing edges of the sub-shelves 15a, 15b and 16a, 16b. This allows a few degrees of angular adjustment from the normal in either direction before either the facing edges of the sub-shelves come into contact with each other, or the angle between the sub-shelves becomes too great to lay the cables over without sagging.

The external corner fitting is completed by a cover member, shown in Figure 7. The cover member is made in two parts, 30 and 31 which are provided with a limited pivoting movement with respect to one another to take up discrepancies in the angle of the corner from the expected normal. This pivoting movement is provided by upper and lower pegs 32 (only the lower peg is visible) formed on the inside of cover part 30 which engage in respective slots 33 in cover part 31.

Each cover part 30, 31 is shaped so as to match the external contour of the cable trunking (see Figures 1 and 2) so that, when fitted, the cover member completely covers the gap between the two cut ends of the trunking profiles to be joined round the corner. Lugs 34 are formed as shown in order to engage the base member to securely attach the cover member to the base member.

Referring now to Figures 8 to 11, there is shown the base member for an internal corner fitting for cable trunking of the type illustrated with reference to Figures 1 and 2.

The base member comprises a panel 41 which has two flat -11 -sections 42, 43 between which is a central section 44 which is curved about an axis of curvature which, in use, is vertical. Extending from the upper edge of the central section 44 to its lower edge is a line 45 of thinner material which forms a living hinge dividing the panel 41 and indeed the whole base member, into two symmetrically matched sections 46, 47.

Extending from the front-facing surface of the panel 41 are two shelves 48, 49. Each shelf is made of two individual sub-shelves 48a, 48b and 49a, 49b on each side of the living hinge 45, as shown. The upper shelf 48 is designed to be at approximately the same height as the upper partition 3, 9 in the trunking shown in Figures 1 and 2. The lower shelf 49 is designed to be at approximately the same height as the lower partition 4 in the trunking shown in Figures 1 and 2. In this way data and power cable can be supported as it is routed round the corner and the curvature of the panel, in conjunction with the design of the cover member (see below) ensures that the cable is not subjected to too tight a curve.

Between the underside of each of the upper sub-shelves 48a, 48b and the front surface of the panel 41 is a respective fillet 50 which defines a surface 51 from each of which a peg 52 extends. A similar fillet 53 is formed between the topside of each of the lower sub-shelves 49a, 49b and the front surface of the panel 41 which define further surfaces 51 from each of which a peg 52 extends. The purpose of the pegs 52 is to engage in an appropriately positioned slot or hole or other formation in the end of the adjacent trunking profile (not shown), thus securing the base member to the trunking profile. For this purpose, the ends of the trunking profile to be joined by the corner fitting are cut off square and at such a distance from the corner that the edges 54, 57 of the shelves abut up to the cut off ends of the trunking to provide an essentially continuous support for the cable.

The rear surfaces 55, 56 of each of the flat panel sections 42, 43 define abutment surfaces which, when pushed into the internal corner will automatically adjust the angle between the two sections 46, 47 to the particular angle of the corner. For this purpose, the base member is constructed so that, when the angle between the surfaces 42, 43 is the normal expected angle (usually 900, as illustrated), the living hinge is set so s as to leave a small angle, typically about 50, between the facing edges of the sub-shelves 48a, 48b and 49a, 49b. This allows a few degrees of angular adjustment from the normal in either direction before either the facing edges of the sub-shelves come into contact with each other, or the angle between the sub-shelves becomes too great to lay the cables over without sagging.

The internal corner fithng is completed by a cover member, shown in Figures 12 to 16. The cover member is made in two parts 60, 61 which are provided with a limited pivoting movement with respect to one another to take up discrepancies in the angle of the corner from the expected normal. This pivoting movement is provided by upper and lower pegs 62 formed on the inside of cover part 60 which engage in respective slots 63 in cover part 60.

Each cover part 60, 61 is shaped so as to match the external contour of the cable trunking (see Figures 1 and 2) so that, when fitted, the cover member completely covers the gap between the two cut ends of the trunking profile to be joined around the corner. Lugs 65 are formed as shown in order to engage the base member to securely attach the cover member to the base member.

The inside surfaces of the internal corner cover parts 60, 61 together form a curved surface 66 which faces inwardly towards the corner when fitted. The shape and configuration of this curved surface is critical for ensuring that the cable, when routed around the corner, is not bent too tightly. It will be understood that the fitting of the cover member will be carried out after the cable itself is installed and, as the fitting is pushed into the corner for the lugs 64, 65 to engage, the cable can become pushed against the surface 66 and therefore, if this has too small a radius of curvature, damage to the cable can result.

A much improved performance can be realised by providing the surface 66 with specific formations designed to provide a smooth passage of cable round the corner with a radius of curvature sufficient to ensure that damage does not occur. These formations may cover the whole or just a part of the surface 66. In the multi-compartment trunking described with reference to Figures 1 and 2, cable will in practice be confined to the upper and lower compartments and therefore the formations may be likewise confined to just those parts of the surface 66 that may engage the cable as it passes round the corner.

In the particular embodiment illustrated, the formations are arranged into two groups: an upper group 67 corresponding to upper compartment 5 and a lower group 68 corresponding to the lower is compartment 7.

Each group of formations comprises a series of parallel ridges 69 which, when the cover member is fitted, extend approximately vertically.

At their proximal ends, the ridges are attached to the surface 66; at their distal ends the edges of the ridges of each group together define a smooth curved surface for passage of cable round the comer. This is particularly well illustrated in Figures 14 and 16. From these drawings it will be noted that the ridges are formed on both the parts 60 and 61 so that the path of the cable is smooth right around the corner. The ridges can readily be formed during manufacture of the lower parts 60, 61 by injection moulding from plastics material. However, instead of extending radially, as might be expected, the ridges are arranged to have parallel gaps between them, as best illustrated in Figure 16, in order to allow the product to be withdrawn from the mould after forming. In fact, the exact orientation of individual ridges does not matter; what matters is that their distal edges together define a smooth curved path for cable at a minimum radius of curvature, as explained above.

The use of the formations described above enables the internal corner cover member to ensure that the European standards for minimum bend radius are met whilst at the same time having a reasonably tight corner, when seen from the outside. The use of a reasonably tight corner enables the overall size of the corner fitting to be kept to a minimum, and this in turn enables the manufacture of the components by injection moulding at a reasonable cost, thus enhancing the commercial viability of the product.

All of the corner 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 injection moulding.

Another embodiment of the base member of an external corner fitting is illustrated in Figure 17 and 18. The base member is similar to that shown in Figure 3 and 4, in that it comprises a panel which is curved about an axis of curvature which, in use, is vertical. Extending from the upper edge of the panel to its lower edge is a line 87 of thinner material which forms a living hinge dividing the panel, and indeed the whole base member, into two symmetrically matched sections.

Unlike the embodiment shown in Figures 3 and 4, extending from the front-facing surface of the panel are three shelves 82, 84 and 86. Each shelf is made of two individual sub-shelves 82a, 82b; 84a, 84b and 86a, 86b on each side of the living hinge 87, as shown. The upper shelf 82, the middle shelf 84 and the lower shelf 86 are each designed to be at approximately the same height as a respective an upper, middle and lower partition in the trunking. In this way data and power cable can be supported at the upper and lower shelves as it is routed round the corner, the middle area acting, if desired, as a spacing chamber, and the curvature of the panel ensuring s that the cable is not subjected to too tight a curve.

The rear surface of the panel is formed with upper and lower ribs 89and 90 which, like the shelves are each formed as two parts 89a, 89b and 90a, 90b. Unlike the ribs shown in Figures 3 an 4, they do not terminate at the respective side edges of the panel but they do present a reasonably substantial surface 88a, 88b, 91a, 92b from each of which a respective peg 80 extends. Like the embodiment in Figures 3 and 4, the purpose of these pegs 80 is to engage in an appropriately positioned slot or hole or other formation in the end of the adjacent trunking profile (not shown), thus securing the base member to the trunking profile. For this purpose, the ends of the trunking profile to be joined by the corner fitting are cut off square and at such a distance from the corner that the edges of the shelves abut up to the cut off ends of the trunking to provide an essentially continuous support for the cable. Two ears 81 are formed as shown on the vertical edges of the panel to cooperate with the pegs 80 in securely joining the corner fitting to the adjacent trunking. In addition they provide the important function of providing a continuous curved surface for guiding the cable.

As with the earlier embodiment the base member is constructed so that, when the angle between the surfaces of the panel is the normal expected angle, the living hinge is set so as to leave a small angle 82, 84 and 86, typically about 5 , between the facing edges of the sub- shelves 82a, 82b; 84a, 84b and 86a, 86b. This allows a few degrees of angular adjustment from the normal in either direction before either the facing edges of the sub-shelves come into contact with each other, or the angle between the sub-shelves becomes too great to lay the cables over without sagging.

Another embodiment of a base member for an internal corner fitting is shown in Figures 19 and 20. In a similar fashion to the earlier embodiment shown in Figures 8 to II, the base member comprises a panel, and extending from the upper edge to its lower edge is a line 103 of thinner material which forms a living hinge dividing the panel and indeed the whole base member, into two symmetrically matched sections.

Extending from the front-facing surface of the panel are three shelves 95, 97 and 98. Each shelf is made of two individual sub-shelves 95a, 95b, 97a, 97b and 99a, 99b on each side of the living hinge 103, as shown. The upper, middle and lower shelves 95, 97 and 98 are each designed to be at approximately the same height as the respective upper, middle and lower partitions in the trunking. In this way data and power cable can be supported as it is routed round the corner and the curvature of the panel, in conjunction with the design of the cover member ensures that the cable is not subjected to too tight a curve.

The outer edges of each of the lower sub-shelves 99a, 99b are formed with respective flat surfaces 98, 98b for butting against surfaces of adjacent trunking. The upper part of each of the sub-shelves 99a, 99b have a fillet with protruding pegs 93 for fitting in holes, slots or other formations in the adjacent trunking. In similar fashion a pair of sub-shelves 92a, 92b is formed at the top of the base member having flat abutment faces 94a,94b with an underside fillet (not shown) from which the pegs 93 extend. A pair of holes 100 are provided in the cover for receiving screws to attach the cover to a wall.

An alternative cover for the external corner fitting of Figure 3 and 4 is shown in Figure 21. Similar to that shown in Figure 7, the cover member is made in two parts, which are provided with a limited pivoting movement with respect to one another to take up discrepancies in the angle of the corner from the expected normal. This pivoting movement is provided by upper and lower pegs 105 (only the lower peg is visible) formed on the inside of a cover part which engage in respective slots in the other cover part.

Each cover part is shaped so as to match the external contour of the cable trunking (see Figures 1 and 2) so that, when fitted, the cover member completely covers the gap between the two cut ends of the trunking profiles to be joined round the corner. Lugs 102 are formed as shown in order to engage the base member to securely attach the cover member to the base member. The tugs 101 and 103 are provided in order to provide flat surfaces to support the cables, and in the case of plastic trunking to provide continued electrical insulation between the compartments.

Figures 22, 23 and 24 show details of a further cover member suitable for use with the base member illustrated in Figures 8 and 9. The cover member is similar to that shown in figures 13, 14 and 15, and identical reference numerals have been use in respect of similar features.

The main difference being the provision of additional and longer lugs 70,71 in juxtaposition with the tugs 65, but located protruding outwardly immediately below the surface formations 69. The main function of the lugs 70, 71 is to provide a surface to support the cabling, and in the case of plastic trunking to provide continued electrical insulation between compartments.

The base members illustrated in Figures 17 and 18 can be used in combination with the corner fitting illustrated in Figure 7 to form a corner fitting. The base members illustrated in Figures 3, 4 and Figures 8, 9 can be combined with the associated covers of Figure 7 and Figures 12 to 16 respectively; and also combined with the associated covers of Figure 21 and Figures 22 to 24 respectively.

Figures 25a and 25b illustrate the manner in which the corner fittings in accordance with the present invention increase the spacing within cable trunking for receiving the cabling. Figure 25a is typical of a conventional 50mm depth trunking using a conventional corner fitting, and it will be observed that the cross sectional area (CSA) available for the cables as they turn the corner is reduced by approximately 21%. In contrast the living hinge adopted by the present invention enables the base member to be so snugly fitted to a corner (Figure 25b) that there is virtually no reduction in CSA within the trunking.

Claims

CLAIMS

1. A corner fitting for cable trunking, said corner fitting comprising a base member having cable support means for supporting cable passing from one length of cable trunking to another length of cable trunking round a corner, and a cover member for covering the gap between the ends of said lengths of cable trunking, the corner fitting being characterised in that the base member is angularly adjustable.

2. A corner fitting as claimed in claim 1, wherein the angular adjustability of the base member is selected to enable the base member to be fitted into corners formed by surfaces between which the angle is in a range about an expected angle.

3. A corner fitting as claimed in claim 2, wherein the expected angle is 900.

4. A corner fitting as claimed in any of claims I to 3, wherein the base member comprises two sections separated by a hinge.

5. A corner fitting as claimed in claim 4, wherein the hinge is formed as a living hinge between two otherwise integrally-formed sections.

6. A corner fitting as claimed in claim 4 or claim 5, wherein, when fitted, the axis of the hinge will be parallel to the line which forms the intersection of the two surfaces which form the corner.

7. A corner fitting as claimed in any one of claims I to 3, wherein the base member comprises a panel having a living hinge extending across it -20 -and dividing the panel into a first section and a second section hinged with respect to one another by the living hinge.

8. A corner fitting as claimed in claim 7, wherein on each section of the panel is formed at least one shelf for supporting cables as they pass around the corner.

9. A corner fitting as claimed in claim 8, wherein there are two shelves on each section of the panel.

10. A corner fitting as claimed in claim 8, wherein there are three shelves on each section of the panel.

11. A corner fitting as claimed in any one of claims 8 to 10, wherein to is avoid excessive bending of the cable, the shelf or shelves are placed at a height which corresponds to a partition or partitions in cable trunking they are intended for.

12. A corner fitting as claimed in any one of claims 8 to 10, wherein the corresponding shelves on the two panel sections are positioned at slightly different heights from each other, the difference being insufficient to result in excessive cable bending as the two panel sections hinge with respect to one another, but whereby the shelves can overlap so that they do not collide with one another.

13. A corner fitting as claimed in any one of claims 8 to 10, wherein the corresponding shelves are at the same height, and their facing edges on the two panel sections are angled in the plane of the shelf to allow a small amount of adjustment about a mean position.

14. A corner fitting as claimed in claim 13, wherein the mean position is the position of the hinge at the expected normal angle of the corner (probably 900).

15. A corner fitting as claimed in any one of claims I to 14, wherein the fitting is adapted for use as an internal corner fitting or an external corner fitting.

16. A corner fitting as claimed in any one of claims I to 15, wherein the io cover member is adjustable.

17. A cover member for an internal corner cable trunking fitting, said cover member being characterised by having formations protruding from its inside surface which act together for guiding cable around the internal corner at a predetermined minimum bend radius.

18. A cover member as claimed in claim 17, wherein the cover member is adjustable type, having two sections hinged with respect to one another in order to cater for corners formed by surfaces between which the angle is other than expected.

19. A cover member as claimed by claim 17 or claim 18, wherein the formations are formed on both sections so as to smoothly route the cables around the corner, whatever the adjustment setting of the fitting.

20. A cover member as claimed in any of claims 17 to 19, wherein the formations are only in those parts of the cover member where cable is expected to be installed.

21. A cover member as claimed in any of claims 17 to 20, wherein the -22 -formations take the form of parallel ridges extending from the internal surface of the cover member.

22. A cover member as claimed in claim 21, wherein the distal edges of the ridges act together to define a predetermined minimum bend radius for cables routed round the internal corner.

23. A corner fitting as claimed in any one of claims I to 16 wherein, when installed to a corner, the effective cross-sectional area for cables io guided and supported around the corner in the corner fitting is substantially the same as the cross-sectional area for cables along straight sections of the trunking.