Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Title: ELECTRICAL OUTLET BOX
FIELD OF THE INVENTION 2 12 7 0 7 3
This invention is concerned with an electrical, outlet box, and
more particularly is concerned with an electrical outlet box, for mounting
on a wooden or other stud, or any suitable vertical surface, by means of
screws or other suitable fasteners.
1 0 BACKGROUND OF THE INVENTION
Electrical outlet boxes of the metallic, knock down type are well
known. Commonly, they comprise a U-shaped metal plate forming the top,
bottom and rear walls of the box and two, flat metal side plates closing the
open sides of the U-shape plate, to form side walls on the box. The side
1 5 plates are usually connected by way of an interconnecting lug and slot
arrangement at one end of each side plate and a screw at the other end. The
screw is threaded through a tab of the U-shaped plate and bears against the
side plate, to hold it securely in position.
Due at least partially to the provision of these attachment
2 0 arrangements, the sides of the electrical box can be uneven. To enable theelectrical box to be mounted evenly and parallel to a stud, each side plate is
commonly provided with a series of bosses, for example, 4 bosses. These
levelling bosses are usually part-spherical projections, formed by pressing
from each side plate.
2 5 To secure the electrical box in position, the side plates are also
commonly provided with extensions at their upper and lower ends, which
in the assembled box, extend above and below the box as a whole, i.e. above
and below the U-shape plate. These extensions, typically, have a plurality of
holes, to enable an electrician to insert nails through the holes and into a
3 0 stud.
The side plates also are commonly provided with internal
slots, for fasting elements. Electricians will often prefer to use these slots,
and secure the electrical box by screws inserted through the slots into the
wooden stud. It can be noted that, internally, screws usually have to be
3 5 used, since it is not possible to hammer a nail that passes through a slot
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inside the box.
Since these slots are usually spaced some distance from the
bosses, if the screws are tightened too much, the side plate can be distorted.
In extreme cases this can cause the side plate to disengage from the U-shaped
5 plate forming the body.
A further disadvantage is that the head of the screw protrudes
some distance into the interior space of the box and may touch the
conductor terminals located on the side of an electrical device, e.g. a switch
or outlet socket. This could cause an electrical short, which often is only
10 discovered after the installation is completed. A further possibility is that the screw might simply touch one terminal, rendering the box live, but
without causing a short circuit. This renders the box dangerous, and
increases the possibility of a subsequent electrical failure, or possible fire.
Accordingly, it is desirable to provide a side plate, for use in
1 5 electrical outlet boxes, and an electrical outlet box incorporating such an
improved side plate, which eliminates or reduces the problems associated
with conventional side plates, as detailed above.
More particularly, it is desirable to provide a side plate and
associated electrical box, which is not susceptible to bending or deflection,
2 0 when the side plate is secured by screws. Further, the side plate ideally
provides means for recessing screw heads, at least to a certain extent, so as tolargely eliminate the possibility of electrical shorting.
SUMMARY OF THE PRESENT INVENTION
2 5 In accordance with the present invention, there is provided a
side plate for forming a side of a metallic knock down, electrical outlet box,
the side plate comprising: a generally rectangular planar main body; first
and second extensions at first and second ends respectively of the main
body; respective attachment means for releasably attaching the first and
3 0 second extensions to top and bottom walls of a box; and at least one
embossed portion on one side of the side plate and an aperture in the
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embossed portion for receiving a fastening element, for securing a side plate
against a mounting surface.
Preferably, the aperture is provided about an axis, with the axis
angled toward the front edge of the side plate, on the side opposite from the
5 embossed portion.
More preferably, the embossed portion includes a planar or
conical central section, for abutting the head of a screw. The aperture
preferably comprises a main portion around the axis for receiving the screw
shaft and advantageously an outer portion, for receiving part of the screw
1 0 head. The outer portion is located adjacent to the plane of the main body, so
as to minimize or reduce protrusion of the screw head above the plane of
the main body.
This embossed portion can be provided in addition to
conventional bosses for spacing the side plate and electrical box from a stud
1 5 or other vertical surface. In this case, the embossed portion can have a lesser
height then the conventional bosses, all relative to the plane of the side
plate. Alternatively, the side plate may have two conventional bosses
towards the rear edge, thereof and two embossed portions according to the
present invention closer to the front edge thereof. The embossed portion
2 0 and the bosses would then all be of comparable height relative to the plane
of the main body.
In accordance with another aspect of the present invention,
there is provided an electrical outlet box comprising: top, bottom and rear
walls; and a pair of side plates, extending between the top, bottom and rear
2 5 walls, wherein each side plate is generally planar and has a front edge
defining a front, side edge at an open end of the outlet box, and, on each side
plate, at least one embossed portion on one side of the plate, which
embossed portion includes an aperture for receiving a fastener.
Preferably, the side plate is in accordance with the first aspect of
3 0 the invention, with the attachment means of the side plate being releasably
attached to the top and bottom walls of the body.
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BRIEF DESCRIPTION OF THE DRAWING FIGURES
For a better understanding of the present invention and to
show more clearly how it may be carried into effect, reference will now be
5 made, by way of example, to the accompanying drawings, which show
preferred embodiments of the present invention:
Figure 1 is a perspective view of a first embodirnent of an
electrical box in accordance with the present invention;
Figure 2 is a plan view of a side plate of the electrical box in
10 Figure 1;
Figure 3 is a sectional view along line Z-Z of Figure 2;
Figure 4 is an end view of the side plate of Figures 2 and 3;
Figure 5A is a sectional view along line XX of Figure 2, and
Figure 5B is an enlarged sectional view along line XX;
Figure 6 is a perspective view showing mounting of the
electrical box, with one side plate removed;
Figure 7 shows a plan view of a second embodiment of the side
plate; and
Figure 8 shows a perspective view, similar to Figure 6 of an
2 0 electrical box incorporating the second embodiment of the side plate.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The first embodiment of the metallic, knock down electrical
outlet box 1 of the present invention is shown in Figures 1-6. It has a U-
2 5 shaped plate 3, which forms a top wall 5, a bottom wall 7, and a rear wall 9,
of the box. Two generally rectangular side plates 15 are provided, for
forming sides of the box to close the box.
Each side plate 15 has a rectangular main body panel 17. As
shown, rear corners of the panel 17 are cut back, as indicated at 19.
3 0 The side plates 15 have first and second ends, and are identical
to simplify manufacture. Hence, the first end will be the upper end on one
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side and the lower end on the other side, while the second end will
slmilarly be at the lower end on one side and the upper end on the other
slde.
At the first end, there is a first extension 21, with a second
extension 23 at the second end. In known manner, each of the extensions 21
and 23 includes a pair of holes 25, 37 for receiving nails, to enable it to be
nailed to a stud.
In known manner, the connecting means for the first
extension 21 includes a generally triangular-shaped opening 27, between the
1 0 holes 25. The top wall 5 has a locking lug 29, best shown for the bottom wall
7 in Figure 6, adapted to engage the triangular opening 27, and also an
auxiliary projecting tab 31.
In the second extension 23, an approximately T-shaped opening
33 is provided. Adjacent to the opening 33, a conical recess 35 is formed.
1 5 The holes 37 are provided on either side of the opening 33. The lowermost
portion 39 of the second extension 23 is curved, as best shown in the view of
Figure 4.
The top and bottom walls 5, 7 are each provided with a
projecting tab 41 (Figure 6), recessed slightly from the main plane of the
2 0 respective wall. Each tab has an opening 43 for a screw. In no known
manner, and as shown, the tab 41 is inserted through the opening 33, and a
screw 34 is inserted through the opening 43 and engages the side face of the
plate, at the small recess 35. The curved portion 39 and the configuration of
the opening 33 ensure that the head of the screw is not obstructed.
2 5 In known manner, each of the top and bottom walls 5, 7 is
provided with a locking lug 29 and a projecting tab 41, on opposite sides.
Then, each side plate 15 can be first engaged with one locking lug 29 and
then with a respective projecting tab 41. A screw is then inserted to secure
that side plate 15 in position.
3 0 The configuration of the U-shaped plate 3 can be completed in
known manner. Thus, the plate 3 can include knockouts 51, to enable cables
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to access the box where desired. Cable clamps 53 with associated screws can
be provided, as well as ground connection screws 55. At the front, upper
and lower tabs 57 with threaded bores can be provided for the mounting of
an electrical device. The walls of the plate 3 can include holes and bosses, as
5 desired, in a known manner, to enable it to be mounted against a horizontal
surface.
It will be realized that the securing arrangement for each side
plate 15 results in elements projecting out from the side of the box 1.
Accordingly, bosses 61 are provided in each side plate 15, to ensure that the
1 0 box 1 is uniformly set off from a stud or other vertical surface. Here, four bosses 61 are provided, although the configuration of the bosses can be
varied as desired.
Slots 63 are provided in each side plate 15, for insertion of
securing screws, and such slots 63 are known. They have the disadvantage
1 5 that, since they are located between the bosses 61, a screw force applied at this
point can distort the side plate 15. In extreme cases, this can cause one or
more of the locking arrangements in the first and second extensions 21, 23,
to disengage.
In known manner, to locate the box 1 against a wooden stud,
2 0 tabs 65 are bent from the first and second extensions 21, 23. The tabs 65 are
set back from a front edge 45 of each plate 15, so as to recess the box 1 just
inside the front surface of conventional drywall.
Now, in accordance with the present invention, embossed
portions 77 and apertures 71 for screws are provided. Each aperture 71 can
2 5 be characterized as having a rounded T-shape. The stem of the T-shape
forms a main portion 73 of the aperture, intended to receive the shaft of a
screw, and located on axis 75. This axis 75 is generally the centre of a
respective embossed portion 77. As shown in Figures 2 and 5, the embossed
portion 77 has a generally planar central section 79, and around this, an
3 0 arcuate section 81 connecting it to the plane of the side plate 15.
The stem of the T-shape continues into an outer portion 83,
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adapted to receive the periphery of the head of a screw, as detailed below.
As Figure 2 shows, two such embossed portions 77 and
apertures 71 are provided, uniformly spaced apart and between the
extensions 21, 23. Referring to Figures 5 and 6, in use, the box 1 would be
5 located against a stud, indicated at 47, with the tabs 65 abutting the stud inknown manner to locate the box 1. The box can indeed be affixed by nails
through the holes 25, 37 or screws through the screw slots 63. Here, the box
1 is secured by screws 89 inserted through the apertures 71. The inclination
of the planar central section 79, results in the axis 75 being directed at an
1 0 angle towards the front edge 45 of the side plate and extending through the
front opening of the box 1. This means that a screw 89 can be inserted along
with axis 75, without any difficulty of the screw being either inclined to a
preferred axis, or the installer attempting to insert the screw perpendicular
to the side plate 15 within the confines of the box.
1 5 Figure 5B shows that, when the screw 89 is fully inserted, its
head abuts the planar central section 79, and an edge portion of the screw
head, indicated at 91 is received in the outer portion 83 of the T-shaped
aperture. The screw head is almost entirely accommodated in the embossed
portion 77, and this outer portion 83, so that little or no part of the screw had
2 0 need protrude into the box interior.
This is highly desirable, since it leaves the interior of the side
plate 15 essentially flush. This facilitates installation of electrical devices of
the box, and should virtually eliminate the possibility of unintended short
circuits and the like.
2 5 A further advantage of having the screw inserted at an angle is
that it is at an improved angle, to resist pulling forces on the box 1. Where
the screw is inserted perpendicular to the side plate 15, it will resist such
pulling forces solely in shear. With the screw angle as shown, it will resist
pulling forces, attempting to pull the box forward, both in shear and in
3 0 tension.
Reference will now be made to Figures 7 and 8, which show a
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second embodiment of the present invention. For simplicity and brevity,
like components are given the same reference numerals, and a description
of these components is not repeated.
Whereas in the first embodiment, conventional, plain bosses
5 were provided, in the second embodiment, only 2 such bosses 61 are
provided, towards the rear of each side plate 15. Towards the front edge of
each side plate 15, there are two apertured bosses 93, replacing the forward
bosses 61 of the first embodiment. The basic shape of the bosses 93 can
follow that of the bosses 61. However, as shown, each boss 93 has a circular
1 0 aperture 95, for receiving a screw. The circular aperture 95 is provided in
the side wall as shown, so as effectively to provide an axis 97, inclined like
the axis 75.
Then, in use, as shown in Figure 8, screws 89 can be inserted as
before, at an angle, to secure the box 1 in position.
1 5 In both embodiments, the fact that the screws are inserted
either through the embossed portion 77 or apertured boss 93, results in the
clamping force from the screw being applied directly at the boss. Where
conventional screw slots 63 are used, as these are located between the bosses
61, they can result in distortion of the side plate 15. Here, no such distortion2 0 can occur, and the screws 89 can apply a considerable clamping force to
secure the box 1 firmly, without any significant distortion occurring.
While the two embodiments are configured for use with
screws have planar heads, they could equally be configured for use with
countersunte screw heads. Thus, the central portion 79 in the first
2 5 embodiment, or the surface around the aperture 95 in the second
embodiment, could be conical to abut and hold a countersunte screw head.
It will be appreciated that, while preferred embodiments of the
invention have been shown and described, numerous variations are
possible within the scope of the present invention. In particular, while the
3 0 invention has been described in relation to a box for a single electrical
device, the plate 3 could be exchange for a variety of plates, to provide boxes
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for accommodating 2 or more different devices in known manner.
