GB2240438A

GB2240438A - Screw clamping electrical conductors

Info

Publication number: GB2240438A
Application number: GB9101151A
Authority: GB
Inventors: Steve Siow Kuang Yeo
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-01-27
Filing date: 1991-01-18
Publication date: 1991-07-31
Also published as: GB9101151D0; GB9001909D0

Abstract

An electrical screw clamp comprises screws (4, 5) clamping a lightning rod (9) and a flat conductor (10) respectively and a screw (6) clamping a further, round conductor (11). The lightning rod (9) and flat conductor (10) contact each other. The conductive body (1) connects them to the round conductor (11). A lockscrew (7) prevents removal of the screw (5) and a plate (8), held by the lockscrew (7) prevents removal of screw (4). <IMAGE>

Description

CLAMP FOR ELECTRICAL CONDUCTORS This invention relates to a clamp for clamping electrical conductors together in electrical contact and is concerned particularly but not exclusively with such a clamp in which the electrically connected conductors establish an earth path as for example in lightning protection systems.

A lightning protection system usually comprises a circular section copper ground rod which is held in close physical contact with a copper conductor of the protection system by means of a clamp with a hollow body in which the ground rod and the conductor are held together by weans of a clamping screw. Such clamps are unsatisfactory because the ~,tamping screw may work loose, for example as a result of vibration, thereby affecting electrical continuity. A further disadvantage is that separate designs of clamps are required depending upon whether the electrical conductor is flat or round in section. Additionally, existing designs of clamps do not permit flat and round section conductors to be connected to a common ground rod by means of a single clamp.

It is an object of the present invention to obviate or mitigate the aforesaid disadvantages.

According to the present invention there is provided a clamp for electrical conductors, comprising an electrically conducting body adapted to locate at least two electrical conductors by means of respective clamping elements in electrical connection with a further electrical conductor held in position by means of a separate clamping element. It will be appreciated that the at least two electrical conductors do not need to be present simultaneously; it is merely necessary that the clamp body should be adapted to locate and clamp either or both of said conductors in electrically conducting relationship with the individually clamped further conductor.

The invention will now be further described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a cross-section of one embodiment of clamp in accordance with the invention; Fig. 2 is an end elevation from the right in Fig. 1, and Fig. 3 is a side elevation from below in Fig. 1.

Referring now to the drawings, the exemplary clamp comprises a non-ferrous electrically conductive body 1 of rigid construction with a cavity 2 having- a part cylindrical portion 2a and a rectangular portion 2b with shoulders 2c flanking the portion 2a. A further and separate cavity 3 in the form of a cylindrical bore is provided in the clamp body 1. Each of the cavity portions 2a, 2b and the cavity 3 is associated with a respective clamping screw 4, 5, 6 in screw-threaded engagement with a respective capped hole in the body 1. A further screw 7 is engageable in a tapped hole meeting the tapped hole of the screw 5 at right angles such that the screw 7 can engage the screw 5 and lock it in position.

The locking screw 7 also holds in position against a side of the body 1 a plate 8 carrying a notice cautioning against removal and serving by means of its left-hand edge in Fig. 3 to prevent slackening of the screw 4 by engaging one side of its hexagonal head.

The illustrated clamp serves for the interconnection of a ground rod 9 of an electrical earthing or lightning protection system with a flat (rectangular section) first electrical conductor 10 and a second circular section electrical conductor 11. The ground rod 9 locates snugly in the part cylindrical portion 2a of the cavity 2 whereas the first electrical conductor 10 is contained in the rectangular portion 2b of the cavity 2 and held against the cavity shoulders 2c and the ground rod 9 by means of the screw 5 thereby establishing direct electrical contact between the ground rod 9 and the conductor 10 and also indirect electrical connection by way of the shoulders 2c and the electrically conducting body 1.

The ground rod 9 is held in position by the screw 4 which is itself locked against release by the locking plate 8 held by the locking screw 7 which prevents inadvertent release of the screw 5.

The second conductor 11 is received in the cavity 3 and is in electrical connection with the ground rod 9 by way of the electrically conducting body 1. The screw 6 suffices to hold the conductor 3 against relative movement with respect to the body 1.

It will be appreciated that although the body 1 is capable of connecting both conductors 10 and 11 to the ground rod 9 simultaneously as illustrated, the clamp may equally be used for retaining only one of these conductors in position. For example, if only the circular section conductor 11 is to be connected with the ground rod 9, the cavity portion 2b will be empty and the screw 5 may be omitted. It will be noted in Fig. 1 that the tapped hole for the screw 7 is extended into the cavity 3 so that when the screw 5 is omitted a screw 7 with a longer shank can be used to clamp the conductor 11 in place of the screw 6.

Claims

1. A clamp for electrical conductors, comprising an electrically conducting body adapted to locate at least two electrical conductors by means of respective clamping elements in electrical connection with a further electrical conductor held in position by means of a separate clamping element.

2. A clamp as claimed in claim 1, wherein said body is provided with respective cavities for said at least two electrical conductors and said further electrical conductor.

3. A clamp as claimed in claim 2, wherein one of the cavities for one of said at least two electrical conductors communicates with the cavity for said further electrical conductor.

4. A clamp as claimed in claim 2 or 3, wherein the clamping elements are screws engaging in holes communicating with the respective cavities.

5. A clamp as claimed in claim 4, wherein the clamping screw for one of said at least two electrical conductors is adapted to clamp said conductor into electrical contact with said further electrical conductor, the respective cavities connecting with each other.

6. A clamp as claimed in claim 4 or 5, wherein a locking screw engages the shank of one of said clamping screws so as to lock it in position.

7. A clamp as claimed in claim 6, wherein said locking screw serves to hold in position a plate which engages the head of another of said clamping screws to prevent rotation thereof.

8. A clamp for electrical conductors, substantially as herein described with reference to the accompanying drawings.