GB2181903A

GB2181903A - Earth clamp

Info

Publication number: GB2181903A
Application number: GB08619543A
Authority: GB
Inventors: Arthur Bates; Graham John Spencer
Original assignee: BSR
Current assignee: BSR
Priority date: 1985-10-02
Filing date: 1986-08-11
Publication date: 1987-04-29
Also published as: GB8619543D0

Abstract

An earth clamp includes a body portion 11 mounting a securing screw member 14 by which a band 19 can be tightened about a pipe 10. The clamp includes a terminal screw 22 to which a conductor 23 can be connected. The clamp includes a channel shape cover 25 which can be engaged with the shank of the screw member 13 to provide the assembled clamp with a more pleasing appearance. The cover can be formed as a flat sheet with two jig spaced parallel grooves along which the sheet is folded to form the sides of the cover. <IMAGE>

Description

SPECIFICATION Earth clamps This invention relates to so-called earth clamps for use in buildings and which enable an electrical conductor to be electrically connected to a water pipe or the like.

The revised wiring regulations for buildings can result in a substantial increase in the number of earth clamps which have to be used in the electrical installation of the building.

Whereas in the past the few earth clamps which were required could usually be located in inconspicuous places, with the increase in the number of clamps it is more difficult to hide the clamps. For example, it may be necessary to bond a radiator of a central heating system to the associated pipework where screw joints are utilised.

An example of such an earth clamp is described in British Patent 834091 and while the clamp is electrically and mechanically sound it is essentially functional in its construction and is not therefore of an attractive appearance.

Moreover, it is not easy to keep the surfaces of the various parts of the clamp free of dust.

The object of the invention is to provide an earth clamp in a simple and convenient form.

According to the invention an electrical earth clamp comprises a body portion, a screw member extending from the body and which in use, is tightened to secure the clamp to an article, terminal means whereby an electrical connection can be made to the body portion and a cover engageable over said body portion in use to partly enclose said body portion and said terminal means, said cover being retained in position by its engagement with said screw member.

An example of an earth clamp in accordance with the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a sectional side elevation of the clamp shown in position on a pipe, Figure 2 is a side elevation of the clamp together with a cover, Figure 3 is a plan view of the cover, Figure 4 is an inverted plan view of the cover, and Figures 5 and 6 illustrate in plan view and side elevation respectively an alternative form of cover.

The clamp which is shown in Figs. 1 and 2 is essentially the same as is described in the specification of British Patent 834091 and is shown in its secured position on a pipe 10.

The clamp comprises a channel section body portion 11. Retained relative to the body portion is a screw threaded member 12 in which is engaged a screw member 13 having a head 14 and a pointed tip. The screw threaded member 12 can be in the form of a conventional nut which is retained against rotation relative to the body member by the fact that it is located within a complementarily shaped recess formed in the body portion.

Also forming part of the clamp is an elongated pressure pad 15 which is located between the side walls of the body portion 11 and which has upstanding end portions 16 one of which is provided with a lateral extension 17. Formed in the surface of the pad presented to the screw is a depression 18 and located between the screw and the pad is a metal band 19 which encircles the pipe. The band passes through apertures 20 formed in the side walls of the body portion and conveniently one end of the band is located relative to one of the side walls of the body portion by the fact that it is partly engaged around the thin portion of the side wall defined between the aperture 20 and the adjacent edge of the side wall. In use, the body portion is located in position on the pipe and the free end of the band 19 is wrapped around the pipe and is passed through the apertures 20.

The screw member is then tightened so that the tip of the screw member engages the band at a position where the band overlaps.

As the screw is tightened the two sections of band distort due to the action of the tip of the screw member and as further tightening of the screw member takes place the body portion is urged away from the pipe with the bands being pressed firmly into engagement with the pad member and the indented or depressed portions of the bands entering into the recess 18 in the pad member. Once the screw has been tightened a locking nut 21 is tightened, the shank of the screw defining an unthreaded portion adjacent the head for a purpose to be described.

The extension 17 as shown in Fig. 1 is threaded to receive a screw 22 which is conveniently formed with an integral washer whereby the bared end of a conductor can be retained relative to the extension. The extension also defines ears 24 which act to locate the conductor in position while the screw 22 is tightened.

In order to hide the main portions of the clamp a moulded cover 25 as shown in Figs.

3 and 4 is provided. The cover is of channel section and is formed from synthetic resin material. In its base wall, there is formed a circular aperture 26 which is sufficiently large as to allow the head 14 of the screw member to pass therethrough. The aperture 26 is connected to the adjacent exterior edge of the base wall of the cover by means of a thin slot 27 and opposite the slot, is formed a circular aperture 28 which is of a size to ensure that the wall of the aperture firmly engages the unthreaded portion 13 of the shank of the scew member. The centres of the apertures are positioned so that the apertures overlap but at the same time a restricted opening is provided into the aperture 28 for the threaded portion of the shank. Once the unthreaded portion 13 of the shank of the screw has been forced through the opening it is retained in the aperture 26.As shown in Fig. 2, when the cover is located in position it extends on the one side, slightly beyond the body portion 11 and on the other side, a substantial distance beyond the end of the extension 17.

The side walls of the cover extend towards the pipe 10 and obscure from view most of the body portion 11.

In order to locate the cover against angular movement about the screw member, the side walls of the cover as shown in Figs. 2 and 4, are provided on their inner surfaces, with ribs 29 which extend partly towards the free edges of the side walls and which in use, engage with the ears 24 on the extension 17.

The upper surface of the cover in use, will be provided with lettering indicating that the connection effected by the clip conforms to the appropriate British Standard and also wording to the effect that the connection effected by the clamp should not be removed.

It may be necessary to remove the cover to effect a further electrical connection to the clamp and the purpose of the slot 27 is to allow a bladed instrument such as a screw driver to be inserted therein to relieve the gripping pressure offered by the walls of the aperture 28 upon the unthreaded portion 13 of the shank of the screw member.

The cover described above, being moulded, is not easy to package and as an alterantive, it can be produced in flat sheet form as shown in Figs. 5 and 6 from a synthetic resin material such as polypropylene with two spaced parallel grooves 30 on one side face of the sheet, the two grooves defining fold lines so that once the sheet has been secured in position, the side margins of the sheet can be folded along the fold lines to form the sides of the cover.

The central portion of the sheet is provided with the desired wording and in addition an aperture 31 through which the securing screw of the clamp can pass. In this case the sheet would be trapped btween the locking nut 21 and the body portion 11. If desired however the double aperture as shown in Figs. 3 and 4 may be utilised. Moreover it is possible to provide ribs on the side margins of the sheet, the ribs extending at right angles to the fold lines and positioned to engage once folding has taken place, with a part of the clamp to prevent rotation of the cover about the axis of the securing screw.

Claims

1. An electrical earth clamp comprising a body portion, a screw member extending from the body and which in use, is tightened to secure the clamp to an article, terminal means whereby an electrical connection can be made to the body portion and a cover engageable over said body portion in use to partly enclose said body portion and said terminal means, said cover being retained in position by its engagement with said screw member.

2. A clamp according to Claim 1 in which said cover is of channel form.

3. A clamp according to Claim 2 in which the cover is moulded and is provided on the inner surfaces of the side walls, with ribs for engagement with a part of the clamp to locate the cover on the body portion.

4. A clamp according to Claim 2 in which said cover is formed from sheet material, the sheet material being provided with a pair of spaced grooves which form fold lines.

5. A clamp according to any one of the preceding claims in which the cover defines a first aperture sufficiently large to allow the passage therethrough of the head of the screw member and a second and smaller aperture which forms a restricted opening to the first aperture, the second aperture having a size so that its wall firmly engages the shank of the screw member.

6. A clamp according to Claim 5 including a slot extending from the first aperture to the adjacent edge of the side wall of the cover, said slot being positioned opposite the second aperture.

7. A clamp according to Claim 4 in which said cover is provided with an aperture for location about the shank of the screw member.

8. An electrical earth clamp comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Figs. 1-4 of the accompanying drawings.

9. An electrical earth clamp comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Figs. 1, 5 and 6 of the accompanying drawings.