Electrical junction and switch boxes

A molded synthetic resin open-sided box mountable in walls and ceilings for enclosing terminals and connections for electrical conductors extended through walls of the box, and providing access through a switch plate secured over the open side of the box. The box has integrally molded break-out windows extending between several of the intersecting walls of the box. Each of these break-out windows includes a removable panel retained in a surrounding opening by frangible interconnecting strips or bridge webs on opposite sides of the panel. Mounting screw holes are formed in the synthetic resin of the box at locations adjacent the open side thereof, and spring metal screw retaining clips are mounted in the box adjacent these holes so that parts of the clips project into the path of the shank of a screw extended into the holes to engage the threads on the shank.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to synthetic resin electrical junction and switch 
boxes which include easily removable break-out panels or windows 
facilitating extension of electrical conductors through openings thus 
formed in side walls of the box, and which further provide spring metal 
clips in association with screw holes and facilitating rapid and easy 
securement of a cover plate over the open side of the box by means of 
threaded fastening elements. 
2. Brief Description of the Prior Art 
An improved synthetic resin electrical junction and switch box susceptible 
to construction by a one-shot, two-part molding process is described in 
Donald G. Copp U.S. Pat. No. 3,773,968 assigned to the assignee of the 
present invention. The synthetic resin box described in the Copp 
application works very well in practice, and can usually be constructed 
with no difficulty by a one-shot molding process. Where some types of 
plastic materials are employed in molding the box, however, some 
difficulty has been encountered in obtaining accurate molding of the 
knockout panels or windows formed in such boxes in a way such that the 
required spacing or separation of these windows or panels from the 
remainder of the box is attained. 
Another type of synthetic resin electrical junction and switch box is 
described in our U.S. Pat. No. 3,895,732 issued July 22, 1975, and 
assigned to the assignee of the present invention. The synthetic resin box 
described in the latter patent includes integrally molded break-out 
windows or panels which are formed to lie in a plane which extends at an 
acute angle to two adjacent sides of the box and is surrounded by a gap or 
space separating it from the surrounding portions of the box. Two bridge 
webs hold the panel in position in the window opening and extend between 
adjacent sides of the box, and a pair or parallel guide ribs are provided 
on the inside surface of such removable panel. This construction assures 
that the panel or window can be easily pushed out from the side of the box 
by directing a screwdriver against the inside surface of the panel or 
window at such time as it is desired to extend electrical conductors from 
the outside to the inside of the box through the openings thus formed. 
Another feature of the electrical junction and switch box described in our 
U.S. Pat. No. 3,895,732 is the inclusion of spring metal clips adjacent 
screw holes formed in, or adjacent, the side walls of the box, so that a 
cover or closure plate can be quickly and easily secured across the open 
side of the box, following completion of the electrical connections 
thereto, by the use of threaded screws or similar fasteners engaged with 
the clips. 
BRIEF DESCRIPTION OF THE PRESENT INVENTION 
The present invention is a synthetic resin electrical junction or switch 
box which is easily molded to provide the usual break-out windows or 
panels, but which provides such panels in a form and location such that 
they can be quickly and easily removed from inside the box, and which 
further provides, in conjunction with the panels at a location to provide 
maximum strength and service life to the box, a pair of integrally formed 
or molded screw hole-defining tubular portions. There are also provided at 
a pair of opposed locations on the box adjacent the screw holes thus 
defined, a pair of spring metal screw retention clips which are configured 
to provide positive engagement with a screw or other threaded shanked 
fastening element at locations on opposite sides of the threaded shank. 
An important object of the present invention is to provide a synthetic 
resin electrical junction and switch box which has knock-out panels or 
windows which can be quickly and easily removed from inside the box, and 
which, by its construction, facilitates very rapid securement to the box 
of a cover plate or switch plate, using conventional threaded fasteners 
secured to cooperating screw retaining clips on the box. 
Additional objects and advantages of the invention will become apparent as 
the following detailed description of preferred embodiments of the 
invention is read in conjunction with the accompanying drawings which 
illustrate the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION 
One embodiment of a switch box constructed to incorporate the principles of 
the invention is designated generally by reference numeral 10. The box 10 
includes a plurality of substantially monoplanar walls which define an 
enclosure which is open at one side thereof. The box 10 includes a back 
wall 12, a pair of side walls 14 and 16, a top wall 18 and a bottom wall 
20. The walls are joined to each other at right angles so that the box is 
rectangular in cross-section. The open side of the box 10 is that side 
thereof which is opposite the back wall 12. In use, the open side of the 
box is closed, after installation of the box, by placement and securement 
of a switch plate or other suitable closure plate across the open side 
thereof, using screws or other suitable fastening devices. 
A mounting plate 22 is molded integrally with the box and projects from the 
side wall 16 at substantially a right angle. The mounting plate 22 has a 
plurality of holes or apertures 23 formed therethrough to facilitate 
mounting the box in a wall, ceiling or other conventional location. 
To permit electrical conductors to be extended from the outside to the 
inside of the box 10 for connection to electrical contacts or terminals 
inside the box, a plurality of break-out windows or panels 24 are formed 
in the box. Four of such break-out windows are illustrated in the 
embodiment of the invention shown in FIGS. 1-3. 
Each break-out window 24 includes a removable panel 26 which can be of 
square or rectangular configuration, and which has beveled side edges 28. 
The panel 26 of each break-out window 24 generally occupies a plane which 
projects at an angle other than 90.degree. to the walls of the box which 
are adjacent the respective panel, and between which the respective panel 
extends. 
In FIG. 4 of the drawings, these walls are the top wall 18 and the back 
wall 12. As shown in FIG. 4, the angle defined between the panel 26 and 
the wall 18 is about 135.degree., but in various constructions the angle 
can be between about 120.degree. and about 150.degree.. The removable 
panel 26 is further shown by the detailed illustration in FIG. 4 to be 
geometrically configured and oriented so that its tapered side edges 28 
extend in planes which are substantially parallel to the planes occupied 
by the nearest of the respective side wall 12 or 18. The general 
crosssectional configuration of the panel 26 is illustrated in FIG. 4 to 
be trapezoidal. 
Each of the removable panels 26 forming a part of each break-out window 24 
is surrounded by a space or opening 32 through the box which separates a 
major portion of the panel from the adjacent side walls of the box. A pair 
of bridge webs 34 and 36 form bridges extending between the removable 
panel 26 and adjacent portions of the box which, in the illustrated 
embodiment, are the top wall 18 and the back wall 12. The bridge webs 34 
are relatively thin in transverse dimension, and are secured in position 
by molding one end into the adjacent side wall of the box and the other 
end into the back or inside surface of the removable panel 26. 
It will be perceived that the inside surface 38 of the removable panel 26 
extends substantially parallel to the outside surface 30, and that both 
these surfaces, in the illustrated embodiment, extend at an angle of 
substantially 45.degree. with respect to the top wall 18 and the side wall 
12. The same relationship characterizes the exposed surfaces of the bridge 
webs 34 and 36, except for the terminal surfaces 42 most nearly adjacent 
the removable panel 30. These surfaces extend substantially parallel to 
the nearest respective wall of the box. It will further be noted in 
referring to FIG. 5 that the interior surface of each of the bridge webs 
34 and 36 is preferably semicylindrical in configuration. 
Guide ribs 48 and 50 are formed on the inside surface 38 of each removable 
panel 26 and extend substantially parallel to each. Each guide rib 48 and 
50 is of substantially right triangular cross-sectional configuration, and 
thus has a pair of exposed surfaces 52 and 54 facing toward the inside of 
the box. This configuration facilitates molding of the box 10 by the 
oneshot, two-mold part procedure to which reference has hereinbefore been 
made. The spaced guide ribs 48 and 50 function to permit the point of a 
screwdriver or similar implement to be placed between the ribs when the 
removable panel 26 is to be snapped or broken out of the box. This occurs 
at the time when the installer of the box wishes to extend the end 
portions of electrical conductors from the outside to the inside of the 
box for connection to terminals in the box. It will be noted that the 
inner ends of the bridge webs 34 and 36, in addition to being merged by 
molding with the back surface of the removable panel 26 are also joined or 
merged with a median portion of the two guide ribs 48 and 50. This assures 
that the bridge webs 34 and 36 will afford sufficient retention strength 
to assure that the removable panels 26 remain in their closing positions 
until intentionally removed by a workman using a screwdriver to force them 
out of the box. 
In the embodiment of the invention illustrated in FIGS. 1-8, a pair of 
enlongated, inwardly turned channels or screw hole-defining tubular 
portions 56 and 58 are formed in the top wall 18 and bottom wall 20 of the 
box. The channels 56 and 58 are molded in the walls of the box by turning 
inwardly the central portion of the top wall 18 and bottom wall 20 to form 
a deep indentation or trough extending over a major portion of the length 
of these two walls. Adjacent those edges of the top wall 18 and bottom 
wall 20 of the box which lies nearest the open side of the box, the 
respective channels 56 and 58 are closed to provide a screw hole defining 
tubular end portions 56a and 58a, respectively, having screw holes 60 and 
62, respectively, formed therethrough. The screw holes 60 and 62 are each 
of substantially triangular cross-sectional configuration. 
A spring metal screw retaining clip 66 of the configuration shown in FIG. 8 
is pressed into each of the screw holes 60 and 62, as best shown in FIG. 
7. Each screw retaining clip 66 includes three side portions 68, 70 and 72 
which are integrally connected through bend lines so that each of the side 
portions preferably extends at an angle of about 60.degree. with respect 
to the adjacent side portion (see FIG. 6). 
At the upper end of each of the side portions 68, 70 and 72 of each clip 
66, the spring metal is bent over at a right angle to provide limiting 
flanges 74, 76 and 78. At the lower end of each of the side portions, 68, 
70 and 72, the several side portions are bent inwardly in a reverse 
direction from the direction of bending of the flanges 74, 76 and 78 to 
form inwardly extending screw-engaging flanges 80, 82 and 84, 
respectively. A barb or tine is pressed out of each of the side portions 
68, 70 and 72 and projects upwardly toward the respective limiting flange 
74, 76 and 78, and at an acute angle to the major plane of the respective 
side portion from which it is pressed. These tines are designated by 
reference numerals 86, 88 and 90 in the drawings. 
When the screw retaining clips 66 are pressed into their respective holes 
60 and 62, the tines 86, 88 and 90 mate with small recesses or reliefs 92 
formed in the defining side walls of the screw holes, and extend at an 
angle to the faces of the box such that the clips are retained against 
pulling out of the screw holes. The limiting flanges 74, 76 and 78 bear 
against the top end of the screw hole defining tubular portions in which 
the respective clips 66 are inserted. It will be noted in referring to 
FIGS. 6-8 of the drawings that the in-turned screw-engaging flanges 80, 82 
and 84 of each screw retaining clip 66 define between them, a small 
central aperture or passageway through which the point of the screw may be 
extended, but which is not sufficiently large to permit the enlarged 
portion of the threaded shank of the screw to be extended without firm 
interlocking engagement of these flanges with the threads of the screw. 
A different embodiment of the invention is illustrated in FIGS. 9-11. In 
the embodiment of the invention here illustrated, a synthetic resin 
electrical junction box 100 includes opposed side walls 102, a top wall 
104 and a back wall 106. A pair of spaced break-out windows 24 of the type 
hereinbefore described are formed in a plane extending at an acute angle 
between the top and bottom walls 104 and the back wall 106. 
Secured to the top and bottom walls 104 adjacent the open side of the box 
(which is to the left in FIG. 9, and is opposite the back wall 106), are a 
pair of flanges 110 and 112. The flange 110 extends substantially normal 
to the top wall 104, and had one of its surfaces in coplanar alignment 
with the plane of the opening at the front side of the box 100. The flange 
112 extends substantially normal to the bottom wall 104, and has one of 
its surfaces in coplanar alignment with the flange 110 and with the plane 
of the opening into the box. 
The flanges 110 and 112 function to accommodate, and to mount to the top 
and bottom walls of the box 100, a pair of screw hole defining portions 
114 which are identically configured, and are secured to that side of the 
respective flanges 110 and 112 which is opposite the side thereof in 
alignment with the plane of the opening into the box. It will be noted in 
referring to FIG. 9 that each of the screw hole defining portions 114 is 
substantially trapezoidal in side elevational configuration, and each 
defines a tubular screw hole 116 projecting through the screw hole 
defining portion in alignment with a screw aperture or opening through the 
respective flange 110 or 112. 
Each screw hole defining portion 114 also defines a slot 118 (see FIG. 11) 
which extends substantially parallel to the tubular screw hole 116 and 
functions to receive one leg 120 of a V-shaped screw retaining spring 
metal clip, designated generally by reference numeral 122. Each of the 
screw retaining clips 122 includes, in addition to the leg 120, a second 
leg 124 which is reverse bent in respect to the leg 120 and defines an 
acute angle therewith. The leg 124 of the screw retaining clip 122 has a 
circular hole or aperture 126 formed therein at a location spaced from the 
bend between the legs and in alignment with the tubular screw hole 116 
formed through the respective screw hole defining portion 114 as shown in 
FIG. 11. Each of the screw retaining clips 122 further includes a tab or 
tine 128 pressed out of the plane of the leg 120, and bent inwardly so as 
to extend toward or face the leg 124. The tab or tine 128 projects into a 
complementary slot or recess 130 formed in the respective screw hole 
defining portion 114 adjacent the slot 118 which receives the leg 120 of 
the clip 122. 
In the use of the synthetic resin box 100, the break-out windows 24 are 
removed from the box during installation in the manner hereinbefore 
described. After effecting the desired electrical connections inside the 
box, the switch plate or other cover is then secured across the open front 
side of the box 100 by extending screws 132 through openings in the plate 
and into the screw holes 116 formed through the screw hole defining 
portions 114 on the box 100. The threaded shank of each screw then comes 
into contact with the leg 124 of one of the screwengaging clips 122, and 
tends to force or bias this leg 124 in a direction to result in an 
enlargement of the acute angle between the legs 120 and 124. As the leg 
124 slips back over the threaded shank of the screw as the shank passes 
through the opening 126 in this leg, a ratcheting action occurs in which 
axially separated threads on opposite sides of and around the screw shank 
are interlocked and engaged by the edges of the leg 124 which surround and 
define the opening 126 therethrough. Rapid installation without excessive 
and difficult screwing of the screws can be effected by this arrangement. 
From the foregoing description of a preferred embodiment of the invention, 
it will be apparent that various changes and innovations can be made in 
the illustrated and described structures without departure from the basic 
principles which underlie the invention. Innovations and modifications of 
this type which continue to rely upon such principles are therefore 
intended to be circumscribed by the spirit and scope of the present 
invention, except as the same may be necessarily limited by the appended 
claims or reasonable equivalents thereof.