US3671916A

US3671916A - Single spring wire ground clip

Info

Publication number: US3671916A
Application number: US133965A
Authority: US
Inventors: John J Opalenik
Original assignee: Arrow Hart Inc
Current assignee: Cooper Industries LLC; Arrow Hart Inc
Priority date: 1971-04-14
Filing date: 1971-04-14
Publication date: 1972-06-20
Anticipated expiration: 1989-06-20
Also published as: CA939801A

Abstract

A wire grounding clip uses only one spring wire member provided to engage the securing screw, and a portion of the bridge is pressed out of the plane of the bridge as an abutment in position to support the securing screw against the pressure of the spring wire, so as to hold the screw in a position perpendicular to the bridge to facilitate assembly into the metal box.

Description

United States Patent Opalenik 1 SINGLE SPRING WIRE GROUND CLIP [72] Inventor: John J. Opalenlk, New Britain, Conn.

[73] Assignee: Arrow-Hart, Inc., Hartford, Conn.

[22] Filed: April 14, 1971 21 App]. No.: 133,965

[ 1 June 20, 1972 [56] References Cited 4 UNITED STATES PATENTS 3,432,793 3/1969 Muska et a1 ..339/14 R 2,395,141 2/1946 Poupitch l 5 1/30 Primary Examiner-Marvin A. Champion Assistant Examiner-Robert A. Hafer Attorney-Davis, Hoxie, Faithfull & Hapgood [57] ABSTRACT A wire grounding clip uses only one spring wire member provided to engage the securing screw, and a portion of the bridge is pressed out of the plane of the bridge as an abutment in position to support the securing screw against the pressure of the spring wire, so as to hold the screw in a position perpendicular to the bridge to facilitate assembly into the metal box.

5 Claims, 3 Drawing Figures SINGLE SPRING WIRE GROUND CLIP This invention relates to electric wiring devices commonly known as attachment plug receptacles and outlets. They are designed to receive electric connecting devices known as attachment plug caps to tap 011 current for numerous kinds of electric appliances, tool and devices.

More particularly, the invention relates to grounded type attachment plug receptacles and outlets (herein referred to generically as receptacles) of the kind having three holes and three contacts, one of which isa ground connected contact. Such receptacles are now common and are required by electrical codes as standard equipment in many localities.

Heretofore such receptacles were provided with a grounded contact mounted on a bridge member that supported the receptacle body in position across the open front of an outlet or wall box (herein generically referred to as the metal box). A ground wire terminal was also provided connected with or mounted upon the supporting bridge, so that a wire connection could be made by the installer from the ground terminal to ground. These connections were often forgotten or not made by the installer. Hence, in such instances the only ground connection was from the ground contact through the bridge member and to the metal box by way of the screws which secured the bridge to the box. However, these screw connections were unreliable. Occasionally the mounting screw badly engaged the box or the mounting bridge or both and made poor electrical contact with one or the other of them. The result was a high resistance path from the ground contact to ground and an improper grounding connection existed.

Many attempts have been made to overcome these problems and difficulties and to improve the connections to ground, some of which have provided good results but at a relatively high cost, while others have produced mediocre results or have produced problems of their own or failed to work in every situation and environment.

Among the prior attempts, was a wire spring clip having two wire members connected to the mounting bridge, the clip being formed of a length of wire bent double with the looped end inserted through a small hole in the plaster ear of the mounting bridge while the opposite ends were inserted into a similar hole in the plaster ear on the opposite side of the conventional securing screw aperture. The two parts of the clip were spread for and by passage of the securing screw and tended to take permanent set. This construction proved relatively expensive and also had to be carefully monitored to the quality of the manufactured products up to standard.

According to this invention, only one spring wire member is provided to engage the securing screw, and a portion of the bridge is pressed out of the plane of the bridge as an abutment in position to support the securing screw against the pressure of the spring wire, so as to hold the screw in a position perpendicular to the bridge to facilitate assembly into the metal box.

Thus, it is an object of the invention to provide a wire grounding clip for electric receptacles and other wiring devices, requiring less material and being less expensive to install, and having less tendency to take a permanentset than heretofore.

Other advantages of the invention will appear as it is described in connection with the drawing.

In the drawing:

FIG. 1 is a fragmentary plan view of one end of a mounting bridge embodying the invention;

FIG. 2 is a side view of the bridge shown in FIG. 1; and

FIG. 3 is a fragmentary end elevation view of the bridge shown in FIG. 1.

Referring to the drawing, the invention comprises a U- shaped stamped sheet metal mounting bridge for an insulating body of an attachment plug receptacle (not shown) which has a central transverse portion with opposite ends bent-up perpendicular thereto, only one end 12 being shown in the drawing, for simplicity. The extremities of the upturned ends are bent outwardly in opposite directions to form cars such as 14 which may, and usually do, have extensions to overlie the plaster when the device is used in a wall box.

The usual oval shaped aperture for passage of a securing screw may be provided in the plaster ear, but preferably an aperture 16 is formed as illustrated, with its ends 17 and I8 tapering to a narrow curved apex for a purpose as will be presently described.

To ensure connection to ground automatically when the receptacle is mounted in its metal box in case the installer fails to make the wire e connection from the usual ground wire terminal 13 that is commonly formed on the bridge, or alternatively to avoid the need to make such a connection, a wire clip member 20 of the form illustrated is provided. The clip is fonned of a single length of wire whose mid-portion 22 is slightly offset and lies against the under-surface of the plaster ear while its

ends

23, 24 are bent around opposite side edges of the plaster car 14 through openings or notches 15, so that they lie on the upper surface of the plaster ear. Preferably, the wire possesses good electrical conductivity and sufficient resilience to resist permanent distortion and provide a constant pressure as hereinafter described. To maintain the clip in assembled position, the

tips

25 and 26 of the upper ends are bent down into the tapered ends l7, 18 of the aperture 16, while the offset mid-portion 22 of the clip runs along one edge of the aperture inwardly thereof over the aperture in position to be engaged byand pressed against the shank 32 of the securing screw 30 as it passes through the plaster ear aperture 16.

As illustrated, it will be noted that the pressure portion of the clip is straight while the parts connecting it with the ends of the clip are angled. However, the whole clip may be straight up to the portions that are bent.

Since the clip member applies a constant pressure against the screw in a plane below the surface of the plaster ear, its tendency would be to cant the screw, making it difficult or impossible to screw the screw into the tapped hole in the usual lug 28 of the metal box 29. In order to prevent such tilting, the bridge is stamped to depress a narrow strip 19 of the plaster ear running up to the edge of the aperture 16 adjacent the side of the screw which is opposite to the mid-portion of the clip. The edge of the depressed part 19 forms an abutment in the same plane as the pressure portion 22 of the clip. The clip thus presses the screw against the depressed portion 19 when the screw is installed and before the device is mounted in the box, holding the screw erect. The holding of the screw erect facilitates the mounting of the device in the box, since it enables the screw more easily to be aligned with the tapped hole in the box lug 28. The engagement of the clip against the screw provides a low resistance current path from the grounded box through the screw to the mounting bridge via the clip.

The ends of the clip may be welded, soldered or otherwise secured to the bridge but preferably are secured by bending their ends as above described, and then stamped to ensure a good electrical connection between the clip and the bridge.

Although the pressure portion 22 of the clip is illustrated in the drawing as being under the plaster ear 14, its position may be reversed and the pressure portion may lie upon the upper surface of the plaster ear, with the ends of the clip extending down and being bent under the plaster ear.

Also, the pressure part 22 of the clip may be located on the opposite side (inner side) of the aperture 16 to press on the opposite side of the screw shank. In such case, the depressed part 19 would be'in the portion of the plaster ear that runs from the outer end thereof to the aperture 16.

If it is desired to omit the bent down

tips

25,26, the retention of the mid-portion 22 of the clip in properly assembled position is improved and enhanced by provision of channels or grooves pressed, cut or otherwise formed in the faces of the plaster ear directly beneath and in alignment with those portions of the clip that run over the surfaces of the clip. Said portions may be stamped or pressed into the channels.

From the foregoing, it is clear that the invention provides a simple form of wire grounding clip which may be made and assembled inexpensively from a minimum amount of material and will exert a constant pressure against the securing screw for the purpose of grounding the bridge through the screw to the metal box and that the screw will be held erect during the installation of the device in the metal box to facilitate such installation.

Modifications within the scope of the invention will occur to those skilled in the art. Therefore, the invention is not limited to the specific forms and dimensions as illustrated and described.

What is claimed is:

1. In combination with a metal mounting bridge, the combination comprising a metal mounting bridge of an electric wiring device for mounting the wiring device on a grounded metal box, a grounding clip attached to the bridge for establishing a low resistance path from the bridge to a securing screw and grounded metal box, said bridge having at least one ear which is apertured for passage of a securing screw, an abutment formed integrally with said bridge adjacent one edge of said screw aperture in position to be engaged by one side of a securing screw passing through the aperture, said clip being formed of a single length of wire having its mid-portion extending along the edge of said screw aperture opposite said abutment inwardly of said edge, said abutment being pressed out of the surface of the bridge into the same plane as said midportion of said clip and the force of said wire being constantly exerted in said plane so that said clip holds said screw between itself and said abutment in erect position to facilitate insertion of the screw in a taped hole in the box when mounting the bridge on the box.

2. The combination as claimed in claim 1 in which said clip is attached to said bridge by its ends passing through openings in said bridge.

3. The combination as claimed in claim 1 in which said screw aperture has tapered ends and said clip has its ends bent around the edge of said plaster ear and into said tapered ends.

4. The combination as claimed in claim 1 having channels in the bridge receiving the end portions of said clip to maintain the clip in properly assembled condition against any tendency of it to slide over the surface of the bridge.

5. In combination with a metal mounting bridge for mounting of an electrical wiring device to a wall box, there being a hole in the mounting bridge for passage of a screw having a threaded shank portion for securing the mounting bridge to the wall box, the improvement comprising an element formed of resilient electrically conductive material affixed to the said mounting strap in position to engage the threads of said screw and to exert a yieldable force on the screw on one side and tending to press the screw against the bridge on the opposite side of said hole, the force exerted by said resilient element being coplanar with the point of engagement of the screw with the bridge, whereby the said screw is maintained erect for mounting of the mounting bridge in a wall box.