U.S. patent number 3,810,069 [Application Number 05/278,772] was granted by the patent office on 1974-05-07 for grounding clip for electrical fixtures.
This patent grant is currently assigned to Harvey Hubbell Incorporated. Invention is credited to Frank C. Jaconette, Jr..
United States Patent |
3,810,069 |
Jaconette, Jr. |
May 7, 1974 |
GROUNDING CLIP FOR ELECTRICAL FIXTURES
Abstract
Apparatus for providing a reliable grounding path between
electrical fixtures and their mounting boxes, particularly where
modifications to the conventional nature of the electrical fixtures
are unnecessary. A metal clip is disposed as a conductive interface
between the mounting yoke of the electrical fixture and the
mounting screw utilized to secure the electrical fixture within the
mounting box. Low resistance electrical contacts are maintained by
disposing spring members on the clip to exert continual contact
pressure against both the mounting yoke and the mounting screw.
Sharp protrusions extend from the clip to concentrate the contact
pressure exerted against the mounting yoke and the mounting screw
is engaged by a screw-receiving means on the clip. A spring means
is disposed within the screw receiving means to develop the contact
pressure and also provides for self-adjustabliity to pitch
variations of the mounting screws or to fixed pitch references of
the mounting box.
Inventors: |
Jaconette, Jr.; Frank C.
(Trumbull, CT) |
Assignee: |
Harvey Hubbell Incorporated
(Bridgeport, CT)
|
Family
ID: |
23066306 |
Appl.
No.: |
05/278,772 |
Filed: |
August 8, 1972 |
Current U.S.
Class: |
439/97 |
Current CPC
Class: |
F16B
37/041 (20130101); H01R 4/64 (20130101); H01R
24/78 (20130101); H01R 2103/00 (20130101); F16B
2001/0064 (20130101) |
Current International
Class: |
F16B
37/04 (20060101); H01R 4/64 (20060101); F16B
1/00 (20060101); H01r 003/06 () |
Field of
Search: |
;339/14R
;24/73B,73SC,73SM,73SB ;16/2,3 ;51/41.75 ;85/80 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wolfe; Robert L.
Assistant Examiner: Hafer; Robert A.
Attorney, Agent or Firm: Wooster, Davis & Cifelli
Claims
1. A grounding clip for use with an electrical fixture of the type
having a grounded mounting yoke by which the fixture is secured to
a mounting box with mounting screws extending through slots in the
mounting yoke, said grounding clip comprising: a U-shaped spring
having a first member and a second member, said members being
substantially flat planar members, said members being separated by
a gap of lesser magnitude than the thickness of the mounting yoke,
said first member including an aperture, said second member
including screw-receiving means aligned with said aperture for
engaging a mounting screw, said screw-receiving means including a
pair of cantilever arms, said grounding clip being mountable on the
mounting yoke of the electrical fixture with said members forcibly
bearing against the mounting yoke to establish electrical
continuity therebetween and with said aperture and said
screw-receiving means aligned with one of the mounting yoke slots
to receive a mounting screw, said cantilever arms being deflectable
to slide over and forcibly abut against the threads of the mounting
screw in maintaining electrical continuity therebetween as
2. The grounding clip of claim 1 wherein protrusions extend into
said gap from one of said members, said protrusions being effective
to concentrate the contact pressure exerted against the mounting
yoke and thereby
3. The grounding clip of claim 1 wherein rolled tips are disposed
on said screw-receiving means, said rolled tips being configured to
engage between threads on the mounting screw and effectuate the
electrical continuity.
4. The grounding clip of claim 1 wherein diverging terminations are
disposed on said members, said terminations being effective to
facilitate
5. The grounding clip of claim 1 wherein protrusions extend into
said gap from one of said members, said protrusions being effective
to concentrate the contact pressure exerted against the mounting
yoke and thereby decrease the electrical contact resistance
therebetween; rolled tips are disposed on said screw-receiving
means, said rolled tips being configured to engage between threads
on the mounting screw and effectuate the electrical continuity;
diverging terminations are disposed on said members, said
terminations being effective to facilitate the disposition
6. In an electrical fixture of the type adapted to be mounted in an
electrically grounded metal mounting box, wherein a metallic
mounting yoke supports an insulated body and is connected to a
grounding contact within said body, said mounting yoke having at
least one mounting ear extending therefrom, said mounting ear
containing a slot to receive a mounting screw therethrough in
securing said electrical fixture into the mounting box, the
improvement comprising:
a grounding clip detachably affixed to said mounting ear, said
grounding clip being a U-shaped spring, said spring having a first
member and a second member, said members being substantially flat
planar members, said members being separated by a gap of lesser
magnitude than the thickness of said mounting ear, said first
member including an aperture, said second member including
screw-receiving spring means aligned with said aperture for
engaging the mounting screw, said grounding clip being detachably
retained on said mounting ear with said members forcibly bearing
thereagainst to establish electrical continuity therebetween and
with said aperture and said screw-receiving means aligned with said
slot, said screw-receiving spring means being deflectable to slide
over and forcibly abut against the threads of the mounting screw in
maintaining electrical continuity therebetween as the mounting
screw is axially engaged
7. The combination of claim 6 wherein said screw-receiving spring
means
8. The combination of claim 7 wherein protrusions extend into said
gap from one of said members, said protrusions being effective to
concentrate the contact pressure exerted against said mounting yoke
and thereby decrease
9. The combination of claim 7 wherein rolled tips are disposed on
said cantilever arms, said rolled tips being configured to engage
between threads on the mounting screw and effectuate the electrical
continuity.
10. The combination of claim 7 wherein diverging terminations are
disposed on said members, said terminations being effective to
facilitate the
11. The combination of claim 7 wherein protrusions extend into said
gap from one of said members, said protrusions being effective to
concentrate the contact pressure exerted against said mounting yoke
and thereby decrease the electrical contact resistance
therebetween; rolled tips are disposed on said cantilever arms,
said rolled tips being configured to engage between threads on the
mounting screw and effectuate the electrical continuity; and
diverging terminations are disposed on said members, said
terminations being effective to facilitate the disposition of said
grounding clip on said mounting yoke.
Description
BACKGROUND OF THE INVENTION
The present invention relates to grounding apparatus for electrical
fixtures and especially such apparatus which affixes directly to
the electrical fixture without modification thereof. Hitherto, many
different devices have been utilized to provide a grounding path
between an electrical fixture and its mounting box. The most
conventional approach has been to establish this path with a
bonding jumper which requires that a wire be attached to both the
electrical fixture and the mounting box for providing an electrical
interface therebetween. This approach is very time consuming and
even where sufficient time has been allotted for the incorporation
of the bonding jumper, it is inadvertently disregarded on occasion
to thereby result in a hazardous condition.
Another approach is to establish the grounding path by abutting the
mounting yoke of the electrical fixture directly against the
mounting box to achieve a metal-to-metal surface contact
therebetween. Such a metal-to-metal abutment is not possible in all
mounting arrangements between electrical fixtures and mounting
boxes and therefore, this approach is limited to particular
applications. It is also true, that the contact resistance
resulting at such an abutment between surfaces is very susceptible
to drastic increases from adverse circumstances and therefore, the
reliability of the grounding path established thereby is very
low.
Specially configured metallic clips are utilized in some
applications to establish the grounding path. Disadvantages
accompany the use of these clips to achieve a low resistance
grounding path between the electrical fixtures and the mounting
box. One such clip is that disclosed in U.S. Pat. No. 3,432,793
which is fixedly attached to the electrical fixture and exerts a
spring bias against the mounting screw. Being fixedly attached,
this clip can only be utilized if the electrical fixture is
modified, therefore, it increases manufacturing costs appreciably
and can not be applied directly to conventional electrical
fixtures. Another such clip is that disclosed in my U.S. Pat. No.
3,663,919 which presents a protruding member to be forcibly wedged
between the electrical fixture and the mounting box. Although this
clip is highly regarded for its intended purpose, once it is
installed, the electrical fixture becomes more difficult to remove
from the mounting box and thereby may present a problem during
maintenance.
SUMMARY OF THE INVENTION
It is therefore a general object of the present invention to
provide a grounding path between an electrical fixture and a
mounting box with a clip which minimizes and obviates the
disadvantages of the prior art.
It is a specific object of the present invention to provide a
grounding path between an electrical fixture and a mounting box
with a clip which may be applied directly to the electrical fixture
without modification thereof.
It is a more specific object of the present invention to provide a
grounding path between an electrical fixture and a mounting box
with a clip which in no way inhibits the removal of the electrical
fixture from the mounting box.
It is another object of the present invention to provide a
grounding path between an electrical fixture and a mounting box
with a clip which exerts a continual contact pressure against both
the electrical fixture and the mounting screw securing the fixture
to the box.
It is still another object of the present invention to provide a
grounding path between an electrical fixture and a mounting box
with a clip which includes a screw-receiving means of
self-adjusting pitch.
It is a further object of the present invention to provide a
grounding path between an electrical fixture and a mounting box
with a clip having protrusions which intensify the contact pressure
on the electrical fixture.
These objects are accomplished in one form according to the present
invention by arranging the members of a U-shaped clip to forcibly
grip across the mounting yoke thickness of conventional electrical
fixtures. An aperture is disposed through one member of the clip in
alignment with a screw-receiving means through the other member.
Protrusions are disposed on either member to project into the gap
separating the members and serve to facilitate the electrical
contact achieved with the mounting yoke. Cooperating cantilever
springs are incorporated into the screw receiving means and exert a
force against the mounting screw regardless of its pitch variation
or the pitch reference established by the fixed threads within the
mounting box.
BRIEF DESCRIPTION OF THE DRAWING
The manner in which these and other objects of the invention are
achieved will be best understood by reference to the following
description, the appended claims, and the FIGS. of the attached
drawing wherein:
FIG. 1 is a partial top view of an electrical fixture mounted into
a mounting box with the grounding clip of this invention
incorporated therebetween;
FIG. 2 is a side view thereof with portions of the mounting box
cutaway to illustrate the electrical continuity existing between
the ground terminal of the electrical fixture and the mounting yoke
thereof;
FIG. 3 is an enlarged partial sectional view thereof, taken
substantially along line 3-3 of FIG. 2 to illustrate the
self-adjusting pitch feature of the grounding clip and the
concentrated contact pressure attained with the protrusions
thereof;
FIG. 4 is an enlarged partial sectional view thereof, taken
substantially along line 4--4 of FIG. 1 to illustrate the
conductive path provided between the electrical fixture and the
mounting box by the grounding clip;
FIG. 5 is a top perspective view of the grounding clip;
FIG. 6 is a bottom perspective view thereof; and
FIG. 7 is an enlarged sectional view thereof taken substantially
along line 7--7 of FIG. 6 to illustrate the relative disposition of
the screw-receiving means and the protrusions thereon.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning now to the drawing, and more particularly to FIGS. 1 and 2,
there is illustrated an electrical fixture 10 which is secured into
a mounting box 12 with a grounding clip 14 disposed therebetween in
accordance with this invention. Any suitable electrical fixture 10
could be secured into the mounting box 12 but by way of example, a
standard duplex receptacle outlet 16 has been chosen for use in
this disclosure. To eliminate the safety hazard which would
otherwise exist, the grounding clip 14 provides for the electrical
continuity necessary to achieve a grounding path between the outlet
16 and the mounting box 12.
In general configuration, the mounting box 12 is an open ended
enclosure, having rectangular sides. The mounting box 12 is
fabricated of conductive metal and is electrically grounded by
suitable means, such as connection to a water pipe (not shown). A
mounting flange 18 is provided on the mounting box 12 and has
threaded apertures 20 which engage with mounting screws 22 in
securing the outlet 16 to the mounting box 12.
The outlet 16 has a generally compatible configuration to that of
the mounting box 12 and includes a body 24 made of suitable
insulating material, such as moldable plastic. At the front of the
body 24, identical but separate grounded receptacles 26 are
disposed. Each receptacle 26 includes a pair of spaced slots 28
associated with internal female contacts (not shown) and a
semi-circular opening 30 associated with an internal female
grounding contact (not shown). The female contacts mate with the
male contacts of a plug and the female grounding contact mates with
the male grounding contact on the plug. Screws 32 comprise suitable
terminal means for connecting wire conductors to the female
contacts and thereby provide for electrically energizing the
receptacles 26. A metallic mounting yoke 34 extends across the rear
of the body 24 and is affixed thereto by any suitable means, such
as folding tabs 36. The mounting yoke 34 is also configured to
extend along both sides of the body 24 and project laterally
therefrom to each side thereof to form mounting ears 38. An
elongated slot 40 is disposed through each mounting ear 38 to
permit passage of the mounting screw 22 in alignment with the
threaded aperture 20 of the mounting box 12. A grounding screw 42
comprises suitable terminal means for connecting a ground wire to
the mounting yoke 34 which in turn is electrically connected by
suitable means (not shown) to the female grounding contacts within
the receptacles 26.
The grounding clip 14 is made of resilient, conductive material,
such as a spring metal strip, in a generally U-shaped configuration
which includes an upper plate-like member 44 and a lower plate-like
member 46, with reference to and as illustrated in FIGS. 5 - 7. The
members 44 and 46 are connected to each other at an adjacent end of
each, and separated by a gap 48 of less magnitude than the
thickness of the mounting ear 38. An aperture 50 is formed in the
upper member 44 and a screw-receiving means 52 for engaging with
the threads of the mounting screw 22 is disposed through the lower
member 46, with the longitudinal axes of both the apertures 50 and
the screw-receiving means 52 aligned along a common axis A-A.
Protrusions 54 extend into the gap 48 from the upper member 44 and
the termination of each member 44 or 46 is configured to diverge
relative to the other member 44 or 46 in that an inclined tip 56 is
disposed on the upper member 44 and a locating flange 58 is
disposed on the lower member 46. A spring means 60 of suitable
construction, such as cooperating cantilever members 62, is
incorporated into the screw receiving means 52 and a rolled tip 64
is disposed at the end of each cantilever member 62.
In use the grounding clip 14 is applied to the mounting yoke 34 of
the outlet 16 by forcibly directing one of the mounting ears 38
thereof into the gap 48 separating the upper member 44 from the
lower member 46. A guided entrance 66 is created by the
complementary contours of the inclined tip 56 and the locating
flange 58 of the members 44 and 46 respectively, and serves to
facilitate the initial insertion of the mounting ear 38
therebetween. The members 44 and 46 are deflected in opposite
directions by this insertion which thereby results in contact
pressures being exerted against each side of the mounting ear 38.
Throughout insertion, the grounding clip 14 is manipulated to align
the common axis A--A through the slot 40 in the mounting ear 38.
Being disposed within the gap 48, the protrusions 54 present a
relatively small contact area against the surface of the mounting
ear 38, as illustrated in FIG. 3, and thereby concentrate the
contact pressure. The protrusions 54 may have any suitable
configuration which depends on the contact pressure to be derived
from the deflection attained by the members 44 and 46. Where the
protrusions 54 are configured to derive a very large contact
pressure, the surface of the mounting ear 38 is scraped thereby to
penetrate any nonconductive substances thereon, and results in a
decreased electrical contact resistance. When assembled, clip 14 is
separably mounted on a mounting ear 38.
The outlet 16 is then placed into the mounting box 12 with the
common axis A--A of the grounding clip 14 aligned along the axis of
one threaded aperture 20 in the mounting flange 18. The mounting
screw 22 is then inserted along the axis of the threaded aperture
20 and turned to secure the outlet 16 in the mounting box 12. As
the mounting screw 22 is turned, the threads thereof engage into
both the screw-receiving means 52 of the grounding clip 14 and the
threaded aperture 20. On the screw-receiving means 52, the rolled
tips 64 are configured and disposed to engage between the threads
of the mounting screw 22 and thereby establish electrical
continuity therebetween, as illustreated in FIG. 3. The spring
means 60 is disposed on the screw-receiving means 52 for exerting
contact pressure against the threads of the mounting screw 22 in
that the cooperating cantilever members 62 thereof are forced to
deflect as the mounting screw 22 is inserted therebetween. This
contact pressure is exerted through the rolled tips 64 which are
forcibly abutted against the threads of the mounting screw 22 and
therefore, a decreased electrical contact resistance is
accomplished between the grounding clip 14 and the mounting screw
22. Due to the deflectable nature of the cantilever members 62, the
screw-receiving means 52 is also self-adjusting the pitch
variations between threads on the mounting screw 22 and to fixed
pitch references established by the threaded apertures 20 in the
mounting box 12. Although a plurality of cantilever members 62 are
shown, where desired the spring means 60 could be arranged from a
single cantilever member.
The grounding path through which electrical continuity is
established between the electrical fixture 10 and the mounting box
12 is illustrated by the dotted line in FIG. 4. At the mounting ear
38, the protrusions 54 are forced to bear against the surface
thereof and thereby establish a low resistance interface
therebetween. Since the grounding clip 14 is made of conductive
material and the protrusions 54 are an integral portion thereof,
electrical continuity exists from the protrusions 54 into the upper
member 44 and through to the rolled tips 64 on the cantilever
members 62 of the lower member 46. The rolled tips 64 are forced to
bear against the threads of the mounting screw 22 and thereby a low
resistance interface is established therebetween. Within the
threaded aperture 20 of the mounting box 12, the engaging threads
of the mounting screw 22 establish a low resistance interface which
is retained under a contact pressure by the forces required to
secure the outlet 16 into the mounting box 12.
It should be readily appreciated by those skilled in this art that
the clip embodied by this invention may be applied directly to an
electrical fixture without the modification thereof and utilized to
accomplish a reliable grounding path between the electrical fixture
and a mounting box. Also, the clip exerts continual contact
pressure on the electrical interfaces without inhibiting the
removal of the electrical fixture from the mounting box and
protrusions are disposed on the clip to intensify the contact
pressure exerted against the electrical fixture. Furthermore, the
screw-receiving means of the clip is self-adjusting to the pitch
variations between the threads of the mounting screw and to fixed
pitch references of the threads within the box.
It should be understood that the present disclosure has been made
only by way of example and that numerous changes in details of
construction and the combination or arrangement of parts may be
resorted to without departing from the true spirit and the scope of
the invention, and therefore the present disclosure should be
construed as illustrative rather than limiting.
* * * * *