GB2466980A

GB2466980A - Connector gripping insulation of cable

Info

Publication number: GB2466980A
Application number: GB0900730A
Authority: GB
Inventors: Scott Horner; Alex H Mackie
Original assignee: LUCY AND CO Ltd W
Current assignee: LUCY AND CO Ltd W
Priority date: 2009-01-16
Filing date: 2009-01-16
Publication date: 2010-07-21
Also published as: GB0900730D0

Abstract

An electrical connector for an insulated cable 8 includes a clamp 19 for the conductor and a washer 40 which encircles the cable. The washer has inwardly directed tabs in the form of teeth 48, which grasp the insulation of the cable and prevent it retracting. The teeth may be thinner than the disc of the washer, and may be inclined and resilient. Two washers may be used in apertures 34, 36 in two offset internal walls 32. The connector may be used for a Hybrid Service cable supplying a street lamp.

Description

Electrical Distribution Equipment

FIELD OF THE INVENTION

The present invention relates to an item of electrical distribution equipment.

BACKGROUND ART

In the context of electrical distribution, it is frequently necessary to terminate cables at junction boxes, fuse boxes, switches and other forms of *....* electrical connector. Generally, these include a conductive clamp for the or each S...

conductor within the cable. There may also be a cable grip, intended to relieve : strain on the clamp should there be a tension in the cable. For example, a street S...

or area lighting column will usually have a fused cut-out within the column in which the incoming utility company service cable is terminated. A clamp will **S.S.

* also be provided for a cable leading to the lighting equipment within the column; * the cut-out therefore serves as a demarcation point between the infrastructure owned by the utility company and the infrastructure owned by the local authority or other owner of the lighting column.

SUMMARY OF THE INVENTION

For about the last 10 years, utility companies have experienced a problem of insulation retraction on the phase conductors of Hybrid Service cables, often used to supply street and area lighting. This can be attributed to memory effects in the cross-linked polyethylene insulation which is usually provided around the conductor(s) within the cable. This memory effect is triggered by the elevated ambient temperatures that can be experienced in lighting columns during the summer months, and causes the insulation to shrink. In the vicinity of a connector, this means that the insulation will retract back along the cable, exposing more of the bare conductor.

The present invention therefore provides an electrical connector for receiving an electrical cable comprising a conductor enveloped within an insulating sleeve, the connector comprising a conductive clamp for the conductor and, spaced from the clamp, a encircling structure for the cable having a plurality of inwardly directed tabs.

The tabs can each occupy a segment around the encircling structure of less than about 900, preferably less than about 60°. This would imply at least 4 and preferably 6 or more tabs if they completely encircle the cable.

Metallic tabs can offer both a resilient nature and also a somewhat sharp edge that can dig into and engage with the insulation layer. A washer embedded in the structure of the connector is a convenient way of providing the *.... necessary tabs. Such a washer comprises an annular disc from which the plurality of inwardly directed tabs can project. The tabs are preferably narrower : than the disc, to emphasise their ability to engage with the insulation. S... * S S...

The structure can be in the form of an internal wall within the connector, :" having an aperture through which the cable can pass. Utilities often call for the :" provision of two cable entry points, to allow the incoming supply cable to be looped. In this case, two apertures can be provided in the wall, each with a set of tabs. The wall can then have a stepped profile, the step being formed between the two apertures. This provides greater rigidity to the wall and eases the accommodation of the washers, where these are used.

The present invention also relates to an electrical connector according to any one of the preceding claims in combination with a cable passing though the encircling structure, a conductor of the cable being fixed in the clamp and the tabs being in engagement with a polymeric insulation layer of the cable.

The present invention further relates to a Street lamp, comprising a column containing a connector according to any one of the preceding claims.

This can further comprise a cable leading from the connector to a top portion of the column.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described by way of example, with reference to the accompanying figures in which; Figure 1 shows the internal parts of a connector according to the present invention, in exploded form; Figure 2 shows the wall section of figure 1 in more detail; Figure 3 shows the underside of the connector of figure 1, again in exploded form; Figure 4 shows a retaining washer according to the present invention; * ** S. S Figure 5 shows the connector of figure 1, fully assembled and with a cable S...

*:*. in place; and Figure 6 shows the region V of figure 4 in greater detail.

DETAILED DESCRIPTION OF THE EMBODIMENTS

0*SS** * S Figure 1 shows an embodiment of the present invention. In this case, it shows a connector suitable for use within a street lighting column, typically fitted at the lower end of the column to provide both a point for attachment of the supply cable provided by the electrical utility, and also a fused link to a riser cable that extends to the lighting equipment at the top of the column. Thus, according to Figure 1 the connector 6 is intended to join a supply cable 8 to a riser cable 10 by way of any necessary switches and/or fuses.

A base 12 is moulded out of a suitable plastics or other material, as is conventional in the field, and contains a number of screw clamp terminals 14, 18, 20. The terminal block 14 is provided for the neutral conductors coming from the utility cable, on one side, and for the neutral conductors of the riser cable 10 on the other. Bolts 13 are provided for securing conductors within the terminal block 14, and a screw 15 retains the block 14 on the base 12. A similar connector block (not visible) is provided for the corresponding pair of earth cables.

An insulating dividing wall 16 separates the neutral and earth conductors from an area reserved for the live conductors. An incoming live terminal block 18 are provided for the live conductors of one or more utility cables 8 which are secured in the terminal block 18 by bolts 19 in the conventional manner. A similar terminal block 20 for the live conductors of the riser cable 10 is also provided, separate from the terminal block 18. A screw 21 retains the terminal block 18 in place on the base 12; a similar screw is provided for the terminal block 20. With the connector. unit 6 open (as illustrated) the respective live terminal blocks are separate from each other and no current can flow. Prior to use of the device, an insulating lid (not shown) is fitted over the base 12 and held in place with a plurality of screws 22, 24. A conductive link is attached to an internal face of the lid, so that once the lid is secured in place on the base 12, the conductive contact makes secure electrical connection with the incoming live *.. terminals 18 and the outgoing live terminals 20, thereby closing the circuit and *.* activating the riser cable 10.

Grommets 26, 28 cover the entry ports into the connector 6 and allow the incoming cable 8 to be inserted with adequate environmental sealing.

Referring to Figure 1 and the enlarged part thereof shown in Figure 2, a wall 32 is provided ahead of the incoming live terminals 18. The wall has a pair of apertures 34, 36, each being directly in line with one of the cable entry points of the incoming live terminal block 18. This allows an incoming conductor to be passed through the one of the apertures 34, 36 and clamped in the terminal block 18.

The wall 32 is hollow, comprising a front surface, a rear surface, and top and side surfaces within which is defined a slot extending from the underside of the base 12. This allows a pair of star washers 38, 40 to be inserted into the thus-defined slots 42, 44, as shown in Figure 3. Once these are inserted, the open ends of the slots 42, 44 can be covered by a suitable adhesive label 46, or the slots 42, 44 filled with resin, epoxy, silicone or other forms of sealant.

With the star washers 38, 40 in place within the slots 42, 44, the star washers 38, 40 can slide until they are coterminous with the apertures 34, 36.

Ideally, the slots will be designed so that they are just wide enough for the star washers, allowing the washers to be held in the correct position by friction. Thus a conductor 8 being inserted through the apertures 34, 36 will pass through the star washers 38, 40. As shown in figure 4, each washer consists of an annular disc 46 in the usual style of a washer. From the interior of the annular disc 46, six individual teeth 48 extend. Each tooth is thinner than the disc 46 but of the same metallic material. Each tooth 48 has a frusto-segmental shape and thus acts as an inwardly directed tab. A small gap 50 is left between each tooth 48 so that each can flex independently of the others.

Thus, as shown in Figures 5 and 6, once the incoming live cable 8 is fitted, : it passes through the grommet 28, the aperture 34 (and hence the star washer 38) and its conductor is then attached to the terminal block 18 via threaded bolt * 19, and the insulation material 52 around the conductive element is gripped by * * the teeth 48 of the star washer 38. **** * * ****

Thus, as time passes and the insulative material 52 retracts, it is retained * under gentle tension by the teeth 48 of the star washer 38 and prevented from * * withdrawing.

It will of course be understood that many variations may be made to the above-described embodiment without departing from the scope of the present invention.

Claims

CLAIMS1. An electrical connector for receiving an electrical cable comprising a conductor enveloped within an insulating sleeve, the connector comprising a conductive clamp for the conductor and, spaced from the clamp, a encircling structure for the cable having a plurality of inwardly directed tabs.
2. An electrical connector according to claim 1 in which the tabs each occupy a segment around the encircling structure of less than 90°.
3. An electrical connector according to claim 1 in which the tabs each occupy a segment around the encircling structure of less than 60°.
4. An electrical connector according to any one of the preceding claims in which the plurality of tabs completely encircle an aperture for the cable.
5. An electrical connector according to any one of the preceding claims in which the tabs are metallic.
6. An electrical connector according to any one of the preceding claims in which the tabs are resilient. * * * ** S

**"
7. An electrical connector according to any one of the preceding claims in S..which the tabs form part of a washer embedded in the structure.
8. An electrical connector according to claim 7 in which the washer **.S comprises an annular disc from which project the plurality of inwardly directed tabs.S

*..S.*
9. An electrical connector according to claim 8 in which each tab is narrower than the disc.
10. An electrical connector according to any one of the preceding claims in which the structure comprises an internal wall within the connector, the wall having an aperture.
11. An electrical connector according to claim 10 in which the wall comprises a pair of apertures to accommodate a pair of cables.
12. An electrical connector according to claim 11 in which the wall has a stepped profile, the step being formed between the two apertures.
13. An electrical connector according to any one of the preceding claims in combination with a cable passing though the encircling structure, a conductor of the cable being fixed in the clamp and the tabs being in engagement with a polymeric insulation layer of the cable.
14. A street lamp, comprising a column containing a connector according to any one of the preceding claims.
15. A street lamp according to claim 14 further comprising a cable leading from the connector to a top portion of the column.
16. An electrical connector substantially as herein described with reference to and/or as illustrated in the accompanying figures. * S S ** S **.S * S ** * * * * * S. * S *..****S*S * .SI..... * *