GB2368135A

GB2368135A - Earthing optic fibre splice storage apparatus

Info

Publication number: GB2368135A
Application number: GB0025464A
Authority: GB
Inventors: Raymond Charles Foss
Original assignee: Spirent PLC
Current assignee: Spirent PLC
Priority date: 2000-10-17
Filing date: 2000-10-17
Publication date: 2002-04-24
Also published as: GB0025464D0

Abstract

An optical fibre splice storage apparatus comprises an enclosure having a cable entry port 13 and an electrically conductive member 20 upstanding from the interior surface of the base 10 of the enclosure adjacent the port 13 and extending axially thereof. One end of the member 20 is secured to the sheath 34 of a cable 30 entering the enclosure through the cable entry port 13 and the other end of the device is adapted to mount a device 31 axially of the cable entry port for engaging the ends of tubes 32 extending to trays mounted within the apparatus. In use, the tubes 32 receive one or more optical fibres 33 of a cable 30 entering the apparatus through the port 13. The member 20 securely anchors the cable 30 to the base 10 of the apparatus and also acts as an terminal for earthing the cable and other devices within the apparatus. Clamp 28, cable strength member 29 and apertures/projections 27 for connecting to terminals on the ends of wires to be earthed are shown.

Description

Optical Fibre Splice Storage Apparatus

This invention relates to an optical fibre splice storage apparatus.

It is well known to store splices between the fibres of optical fibre cables in enclosures. Typically, such known enclosures comprise a base portion formed with a plurality of tubular cable entry ports projecting from its underside, through which the cables enter and leave the enclosure.

The splices or joints are contained in trays mounted inside the enclosure. An elongate tubular cap-ended cover is provided for sealingly engaging the base, so as to enclose the splices or joints between the cables.

The cables entering the enclosure generally comprise a sheath or braid of metal which should be earthed inside the enclosure, so as to provide protection against lightening strikes. Also, other metal objects inside the enclosure, such as support cages for the trays, need to be earthed.

Furthermore, connections to earth also need to be provided for monitoring and signalling apparatus inside the enclosures.

Hitherto, earth connections have been provided inside the enclosure by physically wiring the cables etc. to each other. However, it will be appreciated that it is both difficult and time consuming, especially as the sheath or braid of the cable is generally cut back just inside the enclosure, thereby making access difficult.

We have now devised an optical fibre splice storage apparatus which alleviates the above-mentioned problems.

In accordance with this invention, there is provided an optical fibre splice storage apparatus comprising an enclosure having a cable entry port and an electrically conductive member mounted to the interior surface of the base adjacent said port and extending axially thereof, the member having an inner end adapted to engage an earth conductor of a cable which extends

through said port and an outer end upstanding from the base.

In use, the sheath or braid of the cable is terminated to the inner end of the member just inside the enclosure. The member then projects axially into the enclosure, so that leads and wires can easily be connected in electrical contact with the sheath or braid.

Preferably the member is mounted to an upstanding wall of the base adjacent said port.

Preferably the member comprises a bifurcated mounting portion having a pair of projections which respectively engage opposite surfaces of said wall.

Preferably the mounting portion is connected to an elongate body of the member, intermediate opposite ends thereof.

Preferably an annular band is provided for applying around the sheath of the cable and the inner end of the member.

Preferably the outer end of the member is formed with one or more apertures for receiving screws that are used to fasten terminals on the end of wires and leads to the member.

Preferably the member comprises means for engaging a longitudinal strengthening member of a cable extending through said port.

Preferably the outer end of the member is connected to a member disposed axially of the cable entry port for engaging an end of tube arranged to receive one or more optical fibres of a cable entering the enclosure through said port.

Preferably the member is secured to the base by a fastening element.

Preferably the fastening element comprises a screw which extends into the base axially of the cable entry port.

An embodiment of this invention will now be described by way of example only and with reference to the accompanying drawings, in which:

FIGURE 1 is a side view of an optical fibre splice enclosure in accordance with this invention ; FIGURE 2 is a sectional view along the line II-II of Figure 1; and FIGURE 3 is a front view of a portion of an earth terminal of the enclosure of Figure 1 prior to formation thereof.

Referring to Figure 1 of the drawings, there is shown a splice enclosure which comprises a circular base 10 having a tubular portion 11 and an end wall 12 with a plurality of tubular projections extending outwards from its end wall 12 and forming cable entry ports 13.

The interior of the tubular portion 11 is divided by a plurality of upstanding walls 15 into tubular compartments 14, which extend co-axially with the cable entry ports 13.

In accordance with this invention, an elongate earthing terminal 20 is mounted to the base 10 and extends into the enclosure axially of one of the cable entry ports 13.

The earthing terminal 20 comprises a metal mounting portion 21 secured to the base 10 and an elongate metal body 22 attached to the mounting portion 21 intermediate its opposite ends.

Referring to Figures 2 and 3 of the drawings, the mounting portion 21 is formed of a sheet of metal in the form of a strip 26 having a pair of parallel elongate outer arms 24 extending perpendicularly to one side from its respective opposite ends. A central arm 25 also extends parallel to the outer arms 24 from intermediate the opposite ends of the strip 26.

The mounting portion 21 is formed by rolling the outer side edges of the outer arms inwardly about respective parallel axes extending axially of the arms 24 until they reach respective points generally overlying the central axis of the

central arm 25.

The formed mounting portion 21 thus comprises two elongate generally tubular portions extending side-by-side axially of the port 13. The side walls of the tubular portion are split along their length from the lower end thereof to a point adjacent their upper ends. The upper end of the mounting portion 21 is welded to the body portion 22, such that it extends parallel to the lower portion of the body from a point intermediate opposite ends of the body 22.

The upper end of the body portion 22 extends outwardly of the base and is provided with a plurality of apertures and projections 27 for connecting to terminals on the ends of wires to be earthed.

A clamping member 28 may also be provided on the upper end of the body portion 20 for receiving and clamping a strengthening member 29 which extends axially of a cable 30 entering the enclosure through the port 13, to which the terminal 20 is fitted.

The upper end of the body portion 22 of the terminal 20 may also support a device 31, which is arranged to mount the ends of tubes 32, extending from splice trays within the enclosure, axially of the cable 13. The tubes 32 serve to protect the exposed fibres 33 as they pass between the cut end of the cable 30 and the trays.

In order to connect a cable to the enclosure, the free end of the cable 30 is inserted through the cable entry port 13 until it projects well beyond the base 10. The end of the cable 30 is then stripped back to expose its co-axial earth braid or sheath 34. An annular metal clamping band 35 is then applied around the sheath 34 and the lower end of the body 22 of the earth terminal 20 is inserted before the band 35 is tightened.

The cable 30 is then carefully pulled back out of the

port 13 whilst the bifurcated mounting portion 21 of the terminal 20 is guided over the upstanding internal wall 15 surrounding the cable entry port 13. The cable 30 is pulled further until the mounting portion 21 is fully engaged over the wall 15, whereupon the metal clamping band 35 and the exposed sheath 34 of the cable are mounted within the internal tubular compartment 14 formed co-axially with the port 13.

The earth terminal 20 is then secured to the base 10 by applying screws 36 axially of the respective tubular portion of its mounting portion 21, such that the screws bite into the wall 15.

Once fastened, the earth terminal can be connected to wires and leads extending from other such terminals mounted to adjacent ports and from structures and apparatus within the enclosure to be earthed. If desired, the tubular compartments 14 in the base can be filled with a material which encapsulates the exposed sheathes 34 of the cables.

It will be appreciated that the earth terminal enables the earth circuit inside the enclosure to be formed quickly and reliably and also serves as a means for anchoring the end of the cable securely to the base.

Claims

1. An optical fibre splice storage apparatus comprising an enclosure having a cable entry port and an electrically conductive member mounted to the interior surface of a base of the enclosure adjacent said port and extending axially thereof, the member having an inner end adapted to engage an earth conductor of a cable which extends through said port and an outer end upstanding from the base.

2. An optical fibre splice storage apparatus as claimed in claim 1, in which the member is mounted to an upstanding wall of the base adjacent said port.

3. An optical fibre splice storage apparatus as claimed in claim 2, in which the member comprises a bifurcated mounting portion having a pair of projections which respectively engage opposite surfaces of said wall.

4. An optical fibre splice storage apparatus as claimed in claim 3, in which the mounting portion is connected to an elongate body of the member, intermediate opposite ends thereof.

5. An optical fibre splice storage apparatus as claimed in any preceding claim, in which an annular band is provided for applying around the sheath of the cable and the inner end of the member.

6. An optical fibre splice storage apparatus as claimed in any preceding claim, in which the outer end of the member is formed with one or more apertures for receiving screws.

7. An optical fibre splice storage apparatus as claimed in any preceding claim, in which the member comprises means for

engaging a longitudinal strengthening member of a cable extending through said port

8. An optical fibre splice storage apparatus as claimed in any preceding claim, in which the outer end of the member is connected to a member disposed axially of the cable entry port for engaging an end of tube arranged to receive one or more optical fibres of a cable entering the enclosure through said port.

9. An optical fibre splice storage apparatus as claimed in any preceding claim, in which the member is secured to the base by a fastening element.

10. An optical fibre splice storage apparatus as claimed in claim 10, in which the fastening element comprises a screw which extends into the base axially of the cable entry port.

11. An optical fibre splice storage apparatus substantially as herein described with reference to the accompanying drawings.