Self-grounding Clip For The Mounting Strap Of An Electric Switch Or Receptacle

Abstract

A self-grounding clip is provided for snapping into the screw slot of an electric switch- or receptacle-mounting strap and comprises a plate-like body portion having a central cut-out portion cut and bent about parallel fold lines to form two bent legs adapted to snap-fit into the screw slot, one end of the body being also bent out of the plane thereof arcuately about a fold line parallel to the fold lines of the central body legs and adapted to engage the end of the receptacle strap proximate the screw slot.

Description

This invention relates to an attachment for the mounting straps of electric switches and receptacles and, more particularly, to a self-grounding clip for such mounting straps.

Electric switches and receptacles for wall-mounting in a junction or receptacle box are conventionally mounted on a metal strap adapted to span the open face of the box and to be secured thereto by mounting screws. For this purpose, the ends of each strap outboard of the mounted switch or receptacle are provided with a screw slot or hole somewhat larger than the diameter of the mounting screw so as to permit limited lateral movement of the mounting strap as it is being secured in place. The oversize screw slot results in limited contact between the head of the mounting screw and the mounting strap itself and thus cannot generally meet the heat-rise test for an electrical ground connection between the receptacle and the box. As a result, in order to provide such a connection, it has been proposed to supply the mounting strap with a grounding clip which heretofore has had to be welded, staked or riveted to the strap.

I have now devised a self-grounding clip for a switch- or receptacle-mounting strap which snaps into operative position and does not require welding, staking, riveting, or other independent connection means, for insuring the proper grounding connection between the mounting strap and the mounting box. The self-grounding clip of the invention comprises a plate-like metallic body the central portion of which has integrally formed tongues cut and folded about parallel fold lines out of the plane of the body into shapes adapted to be inserted into a screw slot in one of the mounting straps carrying an electric switch or outlet. One end of the plate-like body is bent arcuately out of the plane of the body about a fold line parallel to the fold lines of the central body tongues and is adapted to engage the end of the mounting strap proximate the screw slot. The central body legs are preferably so spaced as to resiliently engage the screw slot and to be further spread apart into engagement with the strap by the action of a mounting screw inserted therebetween.

These and other novel features of the self-grounding clip of the invention will be more readily understood from the following description taken in conjunction with the accompanying drawing in which:

FIG. 1 is a plan view of the self-grounding clip body showing the cut lines that define the tongue portions thereof;

FIG. 2 is a sectional elevation of the clip of the invention;

FIG. 3 is a perspective view of the first step in mounting of the clip on a mounting strap;

FIG. 4 is a side elevation in section showing the clip in its mounted position; and

FIGS. 5 and 6 are side elevations, partly in section, of the clip in position in a mounting strap assembly with a flat head screw and a chamfered head screw, respectively.

As shown in FIG. 1, the self-grounding clip of the invention comprises a plate-like body 10 of resilient, electrically conductive metal such as phosphor bronze, red brass, beryllium copper, or the like, the central portion of which is provided with an H-shaped cut line 11 so as to define integrally formed tongues 12 and 13. These tongues are bent downwardly out of the plane of the plate-like body 10, as shown in FIG. 2, about parallel fold lines 14 and 15 located at the top and bottom of the H. The portions 12a and 12b of the tongues adjacent their fold lines are advantageously flat and are inclined at an angle of about 40.degree. to conform with the slope of the undercut side of a conventional screw head if such a mounting screw is used. The remainder of each tongue is provided with a continued curvature 12b and 13b in a reversing direction. The ends 12c and 13c of the tongues terminate at a distance from one another slightly greater than the width of the screw slot 16 into which they are to be inserted. The end 10a of the body proximate one of the tongues is also bent out of the plane of the body in the same direction as the tongue but is provided with a curvature opposite to that of the proximate tongue 13.

The clip is secured in place as shown in FIG. 3, by first inserting the end 17a of the mounting strap 17 between the pincher-like curved end 10a of the clip and the proximate tongue 13 and by then rocking the clip about its curved end 10a until the tongues 12 and 13 snap into the screw slot 16 in the mounting strap. By virtue of this rocking and snap-fit action, the pincher-like curved end 10a of the clip and the clip tongues 12 and 13 engage the mounting strap, as shown in FIG. 4, and will not shake loose. Thereafter, as shown in FIGS. 5 and 6, a conventional mounting screw 18 is forced between the tongues 11 and 12, thus moving them further apart until the ends 12c and 13c of the tongues engage the body of the mounting strap 17. As a result, the tongues of the clip make uniform contact with the mounting strap 17 so that, when the mounting screw 18 is tightened to hold the mounting strap in place in a conventional mounting or junction box, there will be a thorough ground and heat-rise connection between the mounting screw, the receptacle or switch, the mounting strap and the box.

It will be seen, accordingly, that the self-grounding clip of the invention will remain in position on the mounting strap prior to installation of the strap, that the clip makes a self-grounding connection between the mounting strap and the mounting box when the mounting screw is tightened, and that this contact is achieved without recourse to any welding, staking, riveting, or other separate contact-making operation. If it is desired to maintain a slot-like opening for adjusting the position of the mounting strap, the ends of the sides of the H-shaped cut lines can be interconnected by oppositely bowed cut lines 19 and 20 so as to remove side portions of the clip body 10 and thus widen the transverse dimension of the clip opening for the mounting screw 18.

Claims

I claim:

1. In combination with a substantially flat mounting strap, at least one end portion of the mounting strap defining an aperture for reception of a mounting screw, a self-grounding clip comprising a plate-like metallic body, the central portion of which has integrally formed tongues cut and folded about parallel fold lines out of the plane of the body, said tongues being positioned within the aperture of said mounting strap, one end of said plate-like body being bent arcuately out of the plane of said body about a fold line substantially parallel to the fold lines of the central body tongues and in engagement with the end of the mounting strap proximate the aperture thereof.

2. The combination according to claim 1 wherein said central body tongues are so spaced as to resiliently engage the aperture and are capable of being spread apart further into engagement with the strap by the action of a mounting screw inserted therebetween.

3. The combination according to claim 1 wherein the end portion of each tongue adjacent the plate-like body forms an angle therewith substantially the same as the undercut angle of a mounting screw head.