GB2060281A

GB2060281A - Electric cable barrier

Info

Publication number: GB2060281A
Application number: GB8031017A
Authority: GB
Original assignee: Hawke Cable Glands Ltd
Current assignee: Hawke Cable Glands Ltd
Priority date: 1979-09-25
Filing date: 1980-09-25
Publication date: 1981-04-29
Also published as: GB2060281B

Abstract

An electric cable barrier assembly having a hollow body 10, an electrically conductive pot or sleeve 32 for filler compound and an end cap 24 engageable with the hollow body 10 to compress compound in the pot around cable conductors extending through the body. Insulation, e.g. a sleeve 34 or a coating on the pot 32, is provided between the pot and the conductors to prevent electrical contact between the conductors and an electrically conductive part of the assembly. <IMAGE>

Description

SPECIFICATION Electric cable barrier This invention relates to a cable barrier assembly.

Electric cable barriers are devices which can be fitted to an electric cable to prevent ingress of liquid, gas or solids into the interstices of the cable and the space between the cable cores when the cable sheathing has been removed to allow connection of the cable conductors to some piece of equipment. Recently cable barriers have been proposed which contain a filler comDoundwhich surrounds the cable cores. Barriers of this kind are described in our British Patent Specifications Nos.

1528347 and 1528348.

In order that a cable barrier containing filler compound can be taken apart after the filler compound has hardened it is the practice to dispose the filler compound in a sleeve or pot, the said sleeve or pot being slidably received in the other components of the cable barrier. All this is described in the above mentioned Patent Specifications. In order to withstand the compressive forces applied to the filler compound and to provide electrical continuity between the parts of the cable barrier, the sleeve or pot is usually made of metal or other electrically conductive material.

It is intended that when the barrier is "made off" the cores within the sleeve pr pot should be held away from the sleeve or pot by the filler compound. There is however, always the possibility that one or more of the cores may come to rest in contact with sleeve or pot. For cables having insulated cores this may not matter. In many cases the cable cores are screened by means of a conductor such as an electrically conductive tape, wire, braid or foil. Such screening is particularly used in cables for control circuitry.

When such cable is being used for transmitting signals of very low current, such as is commonly the case in mining, spurious signals can be generated if a cable core comes into contact with a conductive part of a cable gland.

The present invention has been made from a consideration of this problem.

According to the invention there is provided an electric cable barrier assembly comprising a hollow first part through which, in use, the unsheathed individual conductors of a cable extend, a sleeve or pot for filler compound in said first part, at least the interior of a part of said sleeve or pot being insulated, a hollow second part which, in use, receives the cable, the first and second parts being engageable one within the other, means for drawing the first and second parts together in order to apply pressure to the filler compound located in use, in the sleeve around the individual conductors.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing which shows a cable barrier in sectional side elevation.

Referring to the drawing the cable barrier comprises a hollow body 10 externally threaded at one end 12 for connection to a junction box or other piece of electrical equipment. A counterbore 14 is formed at the other end of the body in which a bush 1 6 is received. The bush 1 6 projects out of the counterbore where it is formed with an externally tapered surface 18. An internally tapered ring 20 forms with the surface 1 8 a clamp for cable armour 22. The armour clamping surfaces are held together by means of a cap 24 threadedly connected to the body 10. An end cap 26 is connected to the cap 24. An externally grooved seal 28 is provided in the end cap, the seal being urged into sealing engagement with the outer sheath 30 of the cable upon tightening of the end cap 26 on the cap 24.

An electrically conductive sleeve 32 is provided in the body. The sleeve is dimensioned so as to correspond substantially to the interior dimensions of the body and thereby form a "flame path" between itself and the body, recommended as by British Standard 4683:1971. It will be noted that sleeve 32 is received inside bush 1 6. The sleeve 32 is preferably made of metal. Within the sleeve is a sleeve 34 of a shape corresponding to sleeve 32 and made of electrically insulating material such as natural or synthetic rubber, synthetic plastics, for example a polyamide or a polyester.

It is not essential that the sleeve 34 should correspond in length to sleeve 32 and it may in some circumstances be shorter or longer. In the embodiment shown in the drawing the place where insulation of sleeve 32 is required is at the left hand end thereof (as viewed in the drawing) where the conductors are closest to the sleeve 32.

If desired, therefore, sleeve 34 may extend only along the left hand end 12 of the barrier. It is preferred, however, that the sleeve 34 extend at least into the counterbore since that will help to hold the sleeve in place and prevent it being moved axially out of the barrier when the parts are tightened.

The sleeve 34 may be a separate piece or may be formed as a coating inside sleeve 34, for example by non-conductive plating. When formed as a separate piece it need not correspond in shape with the part of the gland in-which it is located. It may have a continuous or discontinuous surface, for example it may be perforated or the sleeve may be formed from a mesh or case or may even have the form of a helical winding adjacent turns of which may be in contact or spaced apart from each other.

The sleeve may be made up of a plurality of individual rings which if desired can be placed in position around the conductors as the gland is filled with compound. There may be spaces between the rings provided they are not so large as to permit a conductor to come into contact with a conductive part of the gland. When the sleeve does not consist of a continuous surface it may be designed so that it can be compressed as the gland is made off.

The cable barrier assembly just described is used in substantially the same way as known barriers, for example as described in British Patent Specification No.1528348. It may be used in combination with other glands and devices such as stopper boxes.

The invention is not restricted to the construction described with reference to the drawing. As will be evident from the aforementioned Patent Specification No.1528348 many modifications can be made.

The invention is not applicable only to cable barriers as described in our aforementioned Patents, but may be applied to any cable barrier.

Claims

1. An electric cable barrier assembly comprising a hollow first part through which, in use, the unsheathed individual conductors of a cable extend, a sleeve 6r pot for filler compound in said first part, at least the interior of a part of said sleeve or pot being insulated, a hollow second part which, in use, receives the cable, the first and second parts being engagable one within the other, means for drawing the first and second parts together in order to apply pressure to the filler compound located in use, in the sleeve around the individual conductors.

2. An electric cable barrier as claimed in Claim 1, wherefn-the insulation is formed by a sleeve of electrically insulating material.

3. An electric cable barrier as claimed in Claim 2, wherein the insulating sleeve corresponds in shape, at least in part of the sleeve or pot in which it is located.

4. An electric cable barrier as claimed in Claim 2 or Claim 3, wherein the insulating sleeve is spaced form the sleeve or pot.

5. An electric cable barrier as claimed in any of Claims 2 to 4, wherein the insulating sleeve has a non-continuous surface.

6. An electric cable barrier as claimed in any of Claims 2 to 5, wherein the insulating sleeve is formed by a cage, a mesh, a helical winding or a plurality of rings.

7. An electric cable barrier as claimed in any of Claims 2 to 6, wherein the insulating sleeve is made of natural or synthetic rubber or plastics material.

8. An electric cable barrier as claimed in Claim 1, wherein the insulation is formed by a coating on the sleeve or pot.

9. An electric cable barrier substantially as described herein with reference to the accompanying drawing.