GB2116784A - Electrical cable glands - Google Patents

Abstract

A cable gland is provided with an annular part (e.g. a washer 10 or an earthing tag 40) containing a deformable sealing ring 14 or 46 which projects laterally to the extent that when compressed between gland parts, or between a gland part and a fitting wall, a fluid tight seal is formed and electrical continuity established between the annular part and the surrounding gland parts and/or wall. <IMAGE>

Description

SPECIFICATION Electrical cable glands This invention relates to electrical cable glands.

In many environments there is a requirement for a fluid tight seal between parts of a gland and/or between a gland and the wall of a fitting to which the gland is secured to keep out foreign matter, particularly gas and/or liquid. One of the problems encountered is that in order to maintain electrical continuity for example between a gland part and a metal earth tag, the said gland part and earth tag are arranged to contact each other directly and at that point of contact may not make a fluid-tight seal. The present invention has been made with this problem in mind.

According to one aspect of the invention there is provided a cable gland including an annular part adapted to be located between two gland parts or between a gland part and the wall of a fitting to which the gland can be secured, said annular part being made of electrically conductive material, a deformable sealing member being provided at least adjacent the inner surface of said annular part, said sealing member when undeformed projecting laterally from said annular part to a limited extent so that when said annular part is located between two gland parts or between a gland part and the wall of a fitting the sealing member can be deformed sufficiently to bring said annular part into electrical continuity with said gland parts or with a gland part and the wall of a fitting.

In another aspect of the invention there is provided a cable gland including an annular part adapted to be located between two gland parts or between a gland part and the wall of a fitting to which the gland can be secured, a deformable sealing member of electrically conductive material being provided at least adjacent the inner surface of said annular part, said sealing member when undeformed projecting laterally from said annular part, so that when said annular part is located between two gland parts or between a gland part and the wall of a fitting the sealing member is deformed into both sealing engagement and electrical contact between the annular part and the gland parts or gland part and wall of a fitting.

Specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a section through a sealing washer; Figure 2 is a longitudinal section through a cable gland incorporating the washer of Fig.

1; Figures 3a-h illustrate modifications to the washer of Fig. 1; Figure 4 is an earth tag in side elevation; Figure 5 is a section on the line V-V of Fig.

4; Figures 6a-g illustrate modifications to the tag of Fig. 4; and Figure 7 is a side elevation showing further modifications of the earth tag.

Referring to Fig. 1 the washer comprises an annulus 10 of electrically conductive material such as brass. The inner surface 1 2 of the annulus has a concave form and receives a sealing ring 14 of deformable material such as a rubber or plastics material for example neoprene or a deformable metal for example 'lead. The ring 14 is shown in its undeformed condition and is dimensioned so as to project laterally from the annulus 10 as at 16.

There are many circumstances where the washer of Fig. 1 may be used; one example is shown in Fig. 2.

A cable gland comprises a body 20 which is externally threaded at one end 22 for engagement in the wall 24 of a junction box or other electrical fitting. The other end of the body is of larger external dimensions than end 22, thus defining a shoulder 26. If a seal is required between the body and the wall 24 the washer of Fig. 1 is located against the shoulder 26. Whem the body is tightened against the wall the ring 1 4 is deformed until the wall 24 and shoulder 26 bear against annulus 10. The deformation of ring 14 forms a fluid-tight seal between wall 24 and the body 20.In addition electrical continuity is provided by contact of wall 24 and shoulder 26 against annulus 1 0. It is to be appreciated that the relative dimensions of ring 14 and annulus 10 and as between the washer and the parts where a seal is required must be selected so that deformation of ring 14 as described above is brought about. In other words deformation of ring 1 4 must effect sealing and must also permit the parts to make electrical connection by contact with annulus 10.

The washer does not have to be of the construction as shown in Fig. 1: other ar rangements can equally well be used. Some examples are shown in Fig. 3. Thus the ring may have a flattened cross-section and be secured in a groove 30 in the inner surface of annulus 10 (Fig. 3a) or in a channel 32 in the said inner surface (Fig. 3b). Fig. 3c shows a ring 14 of wedge shaped section received in a I correspondingly shaped groove 34 in the in ner surface of the annulus 10. The embodi ment of Fig. 3d is similar to that of Fig. 3a except that the ring 14 has a more rounded cross section. Fig. 3e illustrates the possibility that the ring 1 4 may be fixed to the annulus by bonding for example with a layer of adhe sive 36.Instead of a projecting part of the ring 14 being received in a corresponding recess in the annulus the opposite arrange I ment can be adapted as illustrated in Figs. 3f, g and h. The cross-sectional shape of the annulus need not be rectangular. For example the side walls may be inclined towards each other, preferably radially inwardly as illustrated in Figs. 3d, 39 and 3h.

The invention is particularly useful in connection with a cable gland earth tag. This is in effect a washer which is located on the gland and which has a part that projects from the gland sufficiently to enable a conductor to be attached thereto. Such a tag is shown in Figs.

4 and 5 and comprises a flat body 40 having a bore 42 for receiving a cable gland part and a second bore 44, spaced from bore 42, for attachment to the tag of a conductor. To enable a seal to be made between the tag and the parts surrounding it a sealing ring, as for example described with reference to Figs. 1 and 3 is located in bore 42. In a particularly preferred embodiment, as illustrated in Figs. 4 and 5 a ring 46 of deformable metal such as lead is provided around bore 42. The ring 46 preferably has a channel shaped section which receives the periphery of the tag around bore 42. Such an arrangement can be assembled by forming a ring with an out-turned flange at one end, inserting the unflanged end of the ring through the bore 42 and then spinning the unflanged end to form an out-turned flange.

The arrangement such as described above, where the sealing ring is made of electrically conductive material does not require that material to be deformed sufficiently to allow the parts enclosing the annulus (or more particularly the earth tag) to make electrical contact through the annulus once appropriate electrical connection is made through the sealing ring itself. It is, however, necessary that the sealing ring should deform sufficiently to form a fluid-tight seal.

The sealing ring of metal can be mechanically secured in place such as described in connection with Figs. 4 and 5 or it can be cast in situ. In the latter case it may be useful as shown in Fig. 7 to provide projections 50, slots 52 or serrations 54 or other profiles adjacent the bore 42 to which the metal ring can key.

Other shapes of ring can be used in place of the channel section illustrated in Fig. 5, examples of which are shown in Fig. 6. Figs.

6a, 6b, 6e and 6g show rings 46 with a recess 56 that receives a part of the body 40 adjacent bore 42. In the embodiment of Fig.

6c the body 40 adjacent bore 42 is profiled as at 58 to receive a correspondingly profiled channel-section ring 46. In the embodiments of Figs. 6d and 6f two rings 46 are provided, one on each side of body 40. Rings 46 can be applied directly to the sides of body 40 as illustrated in Fig. 6d or located in rebates 60 as shown in Fig. 6f.

Claims (14)

1. A cable gland including an annular part adapted to be located between two gland parts or between a gland part and the wall of a fitting to which the gland part can be secured, said annular part being made of electrically conductive material, a deformable sealing member being provided at least adjacent the inner surface of said annular part, said sealing member when undeformed projecting laterally from said annular part to a limited extent so that when said annular part is located between two gland parts or between a gland part and the wall of a fitting the sealing member can be deformed sufficiently to bring said annular part into electrical continuity with said gland parts or with a gland part and the wall of a fitting.

2. A cable gland including an annular part adapted to be located between two gland parts or between a gland part and the wall of a fitting to which the gland can be secured, a deformable sealing member of electrically conductive material being provided at least adjacent the inner surface of said annular part, said sealing member when undeformed projecting laterally from said annular part, so that when said annular part is located between two gland parts or between a gland part and the wall of a fitting the sealing member is deformed into both sealing engagement and electrical contact between the annular part and the gland parts or gland part and wall of a fitting.

3. A cable gland as claimed in Claim 1 or Claim 2, wherein the inner surface of the annular part is substantially concave.

4. A cable gland as claimed in Claim 1 or Claim 2, wherein the inner surface of the annular part is substantially convex.

5. A cable gland as claimed in any preceding claim wherein the sealing member is made of plastics material.

6. A cable gland as claimed in any preceding claim wherein the sealing member is of metal.

7. A cable gland as claimed in any preceding claim, wherein the annular part is comprised of an earth tag.

8. A cable gland as claimed in any preceding claim wherein the sealing member is of substantially wedge shaped cross-section.

9. A cable gland as claimed in any of Claims 1 to 7, wherein the sealing member is of, at least, part circular cross-section.

10. A cable gland as claimed in any of Claims 1 to 7, wherein the sealing member is in the form of a channel which receives the annular part.

11. A cable gland as claimed in any of Claims 1 to 7, wherein the sealing member is applied to one or both sides of the annular part.

1 2. A cable gland as claimed in any of Claims 1 to 7, wherein the sealing member is Drovided with a Droiection said Droiection be ing received in a corresponding recess in the annular part.

1 3. A cable gland as claimed in any preceding claim, wherein the sealing member is secured to the annular part.

14. A cable gland substantiallly as described herein with reference to the accompanying drawings.