GB2367955A

GB2367955A - Cable tray

Info

Publication number: GB2367955A
Application number: GB0025138A
Authority: GB
Inventors: William S Thorneycroft; Richard Swann; Geoffrey Cooper; Chesney Orme; Trevor Yoxall; Trevor Cawdron; Jeffrey Stephens; Len Gardiner
Original assignee: Alan Dick and Co Ltd
Current assignee: Alan Dick and Co Ltd
Priority date: 2000-10-13
Filing date: 2000-10-13
Publication date: 2002-04-17
Also published as: WO2002031939A1; AU2001293980A1; GB0025138D0

Abstract

A cable tray, eg for carrying feeder cables for power installations and cellular telecommunications base stations, has an elongate base 1, a pair of side walls 2 and a valley section 3 with a spaced array of fixing locations (8, fig.2) for receiving cable clamps (19, fig.10). The side walls 2 may have channels 11 to receive earthing strips. The base 1 of the tray may have apertures 7 for receive adjustable support legs 6. The cable tray may have a lid 9 with a leg 10 depending from the underside 9b of the lid so that when the lid 9 is closed the leg 10 provides sufficient support for the lid to be used as a walkway. The lid 9 may be fastened to the cable tray via apertures 5a, 5 in the lid and cable tray, respectively. Formations 4a, 4b may be provided to enable the cable trays to be linked.

Description

Cable Tray

The present invention relates to a cable tray, which carries cables along a cable run, and in particular, to cable trays carrying feeder cables for power installations and cellular telecommunication base stations.

Known cable trays comprise elongate members of a U or square shaped cross section, the cable trays also having lids. Cables are positioned to extend through the elongate member and then a lid is fitted on the member so that cables are held within the channel of the U or square of the tray and are protected by the lid.

A disadvantage of this arrangement is that the cables may be held randomly within the tray and indeed can become twisted during installation. Any engineer therefore has to make careful checks to ensure that the cable he is working on, is in fact the correct cable. Tracing cables back to the outlet to which they are connected can be both time consuming and prone to errors, as the lids may have to be taken off each section of trunking before a cable can be traced. Further if cables are attached to pre-set fixings in a tray, because of the weight of the cables, can add to difficulties in installation.

An aim of the present invention is to provide a cable tray which is simple to install and which provides a means whereby cables can be positioned with reasonable accuracy in a cable tray.

A first aspect of the invention consists in a cable tray having a valley section, in which one of more cables can be placed, wherein the valley section has a spaced array of fixing locators for receiving cable holding means when positioned in the valley section.

In particular, the valley section may comprise a base and a pair of upwardly extending spaced walls.

It is particularly preferred that the spaced array of fixing locations comprises a first set of fixing points spaced in side-by-side relationship across the valley section, followed by, in a longitudinal axis of the cable tray, a further set of fixing points, which line up with spacings between the first set of fixing points.

Preferably, three fixing points provide the first set of fixing locations, followed by two fixing points forming the second set.

It is advantageous that each location is formed to allow snap fit engagement with a cable support, for example it would allow for a single action, quick release of a cable clamp. This feature aids positioning of cable clamps in the cable tray, making cable installation both quicker and easier to install.

A particular feature of the invention is the provision of a lid for the tray. This lid is positionable on the cable tray and may have a leg depending therefrom which, when the lid is positioned on the cable tray, extends into the valley section. This leg can provide sufficient

support to enable the lid to be used as a walkway.

It is envisaged that the leg may abut against the base of the valley section or a raised surface on the cable tray such that the lid bows outwards from plane of the cable tray.

A further feature of the invention is that at least one wall of the valley section has means for holding an earthing strip. The earthing strip may be embedded in, or lie in a channel in an upper surface of a wall.

An important feature of the invention, is that the cable trays can be secured together.

Preferably, the cable trays have at one or both ends, interlocking means for attaching a first cable tray to another. Interlocking may be by pin and recess members but it is envisaged that for example, snap-fit interlocking means may be used to secure the cable trays.

Further the interlocking means may in some instances include a hinge which enables a first cable tray to be moved relative to a second cable tray. It is particularly advantageous if the hinge is recessed in the base of the elongate member so that it does not catch on any surfaces during installation.

A further advantageous feature is that the cable tray includes support legs extending therefrom so that the cable tray can be raised from or lowered to a surface on which it is standing. There may be one or several support legs. In particular, the support legs which can be extended, or

shortened according to the height that the cable tray is to be raised above a surface. It is especially advantageous if the support leg is telescopic so that it can contract within itself, rather than being drawn back into the cable tray, where it may catch on cables in the tray.

In the main, the cable trays will be straight elongate members but it is envisaged that cable trays curved at 450 may be provided to go round corners. Alternatively, the curving may be at 300 so that a number of trays can be positioned next to each other so that the trays can be adapted for the area in which they are installed.

Further, a T-junction cable tray may be provided so that series of cable in a main trunking can be split to run along two or more trunking paths.

Where cables are to split, a particularly advantageous feature of the invention is the provision of a cable tray, of a depth which can hold stacked cables which are on more than one plane, for example there may be a double-decker arrangement of cables. This allows engineers to trace cabling more easily, as cables at different levels will be more easily identifiable.

A second aspect of the invention consists in a cable tray comprising a lid and a base member having a valley section in which one of more cables can be placed, wherein the lid is positionable on the cable tray and has a leg depending therefrom, which when the lid is positioned on the cable tray, extends into the valley section such that

it abuts against a base of the valley section, or a raised surface of the cable tray such that the lid bows outwards from plane of the cable tray.

A third aspect of the invention consists in a cable tray comprising a valley section for receiving one of more cables, the cable tray also having a lid member for seating over the vally section, wherein at least one wall of the valley section has an earthing strip.

A fourth aspect of the invention consists in a cable tray having a valley section for receiving one of more cables, wherein the cable tray has adjustable support legs for raising or lowering the cable tray relative to a surface on which it is placed.

Where a lid is positioned on the cable tray, the bowing of the lid from the cable tray provides a convex, rather than a flat upper surface, which means that rainwater tends not to puddle on the lid of the cable tray.

This feature has particular advantages in that it avoids water seeping into the cable tray, so avoiding corrosion or damage of the cables, or shorting.

Alternatively, the leg depending from the lid may be of a relatively short length and this will allow the lid to bow inwards when weight is put on the lid, for example by a person walking across the cable tray. The ability to bow inwards reduces the stresses placed on the lid.

Preferably, the upper surface of the lid has grooves, which provide a non-slip surface for persons walking across

a lidded cable tray.

The cable trays of the invention may be made of plastics material or of metal. When plastics are used, these can be recycled plastics, which are selected according to the environment in which the cable tray is to be used. In the case of metal cable trays, the metal may have apertures to reduce weight of the cable tray and also to keep production costs to a minimum. These apertures also assist in cooling of the cables.

When a series of cable trays are joined it is advantageous that one tray can be moved relative to another, should the cable tray be used on an uneven surface, for example if the cable tray is to run over ducting. It can be beneficial if the cable tray is placed on, for example, a rubber/flexible matting which allows some cushioning between the cable trays when they move relative to one another.

Although the invention has been defined above it is to be understood that it includes any inventive combination of the features set out above or in the following description.

The invention may be performed in various ways and a specific embodiment will now be described, by way of example, with reference to the accompanying drawings, in which: Fig 1: shows a perspective view of the cable tray; Fig 2: shows an above view of an array of fixing locations in the base of a cable tray;

Fig. 3 : shows a perspective view of lid for a cable tray ; Fig 4: shows an end view of a lid for a cable tray in the unflexed position and in the flexed position; Fig 5: shows an cable tray and lid in spaced relationship prior to joining; Fig 6: shows a side view of a number of cable trays joined together by hinging means; Fig 7: shows a perspective view of a number of apertured metal cable trays joined together; Fig 8: shows a number of curved cable trays joined together, together with corresponding lids; Fig 9: shows a T-junction cable tray; and Fig 10: shows an array of cable clamps for holding cables in a stacked arrangement.

The cable tray as shown in figure 1, is formed of an elongate base member 1, comprising a valley section 3 having two upstanding walls 2. The cable tray has connecting means formed of a protuberance 4a at one end and an aperture 4b at the other end, which are for interlocking the cable tray to a further cable tray having corresponding connecting means. There are also substantially vertical channels 5 along the length of the cable tray for receiving a pin or fixing, which is used to join the cable tray to a lid positioned over the valley section 3. Also there is a channel 11 running along the upstanding wall 2, for receiving an earthing strip. Also, there are apertures 7

in the base of the cable tray into which sleeves/legs 6 can be inserted and held. These legs are used for lifting the cable tray away from a surface on which it is positioned.

The legs may be telescoping so that they can also be shortened so that the cable tray can be lowered onto a surface.

Figure 2 shows an above view of a cable tray 1 having wall 2, with connecting means 4a, 4b at either end. There is a spaced array of fixing locations 8 in the base of the cable tray, of a three-two arrangement, much like the formation of the front two rows of a rugby scrum. The fixing locations each may comprise a threaded opening, which may for example, be provided by a nut or thread in the cable tray. A cable clamp can then be threaded onto a bolt, which in turn is located onto the threaded opening.

When nuts provide the threaded opening, they may be permanently fixed, or there may be provision for them to be released from the tray. It is feasible that the locations may comprise a combination of fixed and removable elements.

Figure 3 shows a lid 9 having a substantially flat surface 9a a leg 10 depending from the underside 9b of the lid. The leg as shown is a three section leg but it may be as a single leg or a series of legs running along the underside of the lid.

Figure 4 shows a lid 9 in two positions. Position A is as the lid would be when sitting on cable tray before being pushed into a final position. Position B is when the lid is

pushed into position such that the leg 10 abuts against a surface on the cable tray, causing the lid to bow away from position A.

Figure 5 shows a lid 9 and a cable tray 1 in spaced relationship. The cable tray in this case is of metal and has a series of apertures 12 for weight reduction and cooling. Leg 10 may lock into raised portion located at the base of the cable tray, or it can rest on the base of the valley of the cable tray. Along the top edge of the wall 2 are apertures 5 for receiving fixing means which locate in apertures Sa in the lid to hold the lid 9 on the cable tray 1.

Figure 6 shows a series of cable trays 1 joined together. Cable tray 1 has hinge means 13, having two arms 13a, 13b, each of which are joined to an end of adjacent cable trays. An end of the hinge means is held in a recess 15 in the under side of a cable tray and is held in position by a pin 14, which projects into the cable tray.

The hinge allows cable trays 1 to be positioned relative to one another. In the case of a raised cable tray as shown, a sleeve 6a can be held by the pin 14 attaching the hinge to the cable tray. The pin may also hold a further support leg 15, which is extended to lift the cable tray, away from a surface. The support leg 15, may be of a fixed length, or it may be capable of telescoping for adjustably positioning the cable tray relative to the surface.

Figure 7 shows a perspective view of a series of metal

cable trays, substantailly as shown in figure 6. Although hinges are shown, it is envisaged that other fixing means may be used which allow one cable tray to be moved relative to another. Further, there may be covers at each end of the cable tray, which can be used to prevent water seeping into the cable tray through spaces between the trays.

Figure 8 shows a series of curved cable trays 1 and lids 9. The cable trays 1 are joined together by connecting means 4 on each end of the cable tray 1. Fixing holes 5 are positioned on an outer wall 2 of each tray, the upper surface 11 of which, can receive an earthing strip, The fixing holes can receive pins, screws or other fixing means to attach the lid 9 to the cable tray. The cable trays 1 are also held by plate pieces 17, which are held by fixing means 16, such as pins or bolts. This gives added strength at the inner section of the corner piece, where the cable tray may abut against a wall and flexibly of movement when positioning the cable trays around a wall edge. Also, the plates allow ease of attachment of for example, a metal tray to a plastic tray.

Figure 9 shows a T-junction cable tray, which can be integral with or fitted to a cable tray. There are protuberances/apertures 4a/4b for fixing the T-junction to another cable tray. Also there is a channel 11 for carrying an earthing strip on an outer edge of the cable tray. A main group of cables runs along the central run of the T, 18 which splits into two branches 18a, 18b. The two

branches carry cables that have been split from the main cable run.

Figure 10 shows a cable tray 1 having a valley section 3 with side-walls 2. Along the valley section are apertures 5 for holding fixators, which attach the cable tray to a lid (not shown). Spaced in the valley are cable clamps 19, which are held at fixing locations 8 as shown in figure 2.

For ease of reference, only one row of cable clamps is shown. The cable clamps which are held by bolts 20 can hold two cables running in one plane and a further two cables running in a further plane, so that stacked cables may be held in the cable tray. It is envisaged that the stacked array of cables may not be limited to a double stacked arrangement but muti-stacking of cables is possible. Cable clamps which are of particular applicability for use with the cable tray of the present invention are those described in co-pending UK patent application number 0023658.8, incorporated herein by reference.

Although the invention has been described with specific reference to the drawings it is envisaged that other arrays of cable fixings may be used.

Claims

Claims 1. A cable tray having a valley section, in which one of more cables can be placed, wherein the valley section has a spaced array of fixing locators for receiving cable holding means when positioned in the valley section.
2. A cable tray according to claim 1, wherein the valley section comprises a base and a pair of upstanding spaced walls.
3. A cable tray according to claim 1 or claim 2, wherein the valley section includes a spaced array of fixing locations comprising a first set of fixing points spaced in side-by-side relationship across the valley section, followed by, in a longitudinal axis of the cable tray, a further set of fixing points, which line up with spacings between the first set of fixing points.
4. A cable tray according to claim 3, wherein the spaced array of fixing locations comprises three fixing points spaced in side by side relationship across the valley section, followed by, in a longitudinal axis, two fixing points.
5. A cable tray according to any preceding claim, wherein the fixing locations are snap-fittable to allow for

snap fit engagement with a cable support.
6. A cable tray according to any preceding claim, wherein a lid is positionable on the cable tray and has a leg depending therefrom, which when the lid is positioned on the cable tray, extends into the valley section.
7. A cable tray according to claim 6, wherein when the lid is positioned on cable tray the leg abuts against the base of the valley section, or a raised surface of the cable tray such that the lid bows outwards from the plane of the cable tray.
8. A cable tray according to any preceding claim, wherein at least one wall of the valley section holds an earthing strip.
9. A cable tray according to any preceding claim, wherein the cable trays have at one or both ends, interlocking means for attaching a first cable tray to another.
10. A cable tray according to claim 9, wherein the interlocking means includes a hinge which enables a first cable tray to be moved relative to a second cable tray
11. A cable tray according to any preceding claim,

including a support leg extending therefrom so that the cable tray can be raised from or lowered to a surface on which it is standing.
12. A cable tray according to claim 11, wherein the support leg is telescopic.
13. A cable tray according to any preceding claim, which is curved.
14. A cable tray according to any preceding claim, having a T-junction at one or both ends.
15. A cable tray according to any preceding claim, wherein the cable tray can accommodate stacked cables.
16. A cable tray comprising a lid and a base member having a valley section in which one or more cables can be placed, wherein the lid is positionable on the cable tray and has a leg depending therefrom, which when the lid is positioned on the cable tray, extends into the valley section such that it abuts against a base of the valley section, or a raised surface of the cable tray such that the lid bows outwards from plane of the cable tray.
17. A cable tray having a valley section for receiving one of more cables, the cable tray also having a

lid member for seating over the valley section, wherein at least one wall of the valley section has an earthing strip.
18. A cable tray having a valley section for receiving one of more cables, wherein the cable tray has adjustable support legs for raising or lowering the cable tray relative to a surface on which it is placed.
19. A cable tray substantially as described herein with reference to and as illustrated in the accompanying figures as shown.