Note: Descriptions are shown in the official language in which they were submitted.
6'' BACKGROUND AND OBJECTS OF THE INVENTION
7 !, . 1 . Field of the Invention
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l~ I The present invention relates generally to electrical
. :~ 19 I ouLlet boxes and the like and relates more particularly to
20 ¦ certain new and useful improvements in the configuration and
21 1 structure of the cable entry ports in such boxes which facili~ate
22 ¦ the admission o electrical power cable into the outlet box
23 ~ and retention of the installed cable in the box.
.~ 24 ¦ The usual electrical outlet box is constructed in a
25 ,1 ~enerally open top, box-like configuration with a generally
26 I~, continuo1ls side wall 7nember depending rom a back or bo~tom
27~j, wall, and fo~ned with one or more cable entry ports (hereinafter
28 some~imes referred to as "knockout windows") in the side wall
~ ~29~ me7nber, whlch are adapted to permi~ access of electrical power
- :30 cables ~n~o the interior of the box. One or more electrical .
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power cables are inserted into the box, each th~ough a cable
port opening, for connec~ion,of the conductor wires to, or
3 'termination wi~h, ~he electrical fixture to be ~ounted in the box,
4 . Moreover, ln order to prevent debris from entering the box
5 ~through cable ports that are no~ utilized, and to minimize ~i~e
6 ,spead in the event that t~e electrical appliance housed in ~he
7 box mal~unctions, the typical cable entry ports in electrical
8 ,.outlet boxes axe su~stantially'completely closed by."knockout"
g .panels which are removabiy''attached to the box wall structure
10 'across each port open mg.
~1 It will be understood that.although the present
12 jinvention is descri~ed with particular re~erence to elec~rical
,3 2 outlet boxes w~ich are adapted to house the termination, i.e.,
14 lelectrical connection, between the con-~uctor wires of an elec-
~: ~5 'trical power cable'a~d an electrical fixture'such'as an
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~! ~6 ",electrica~ outlet receptacle or'an electrica~ switc,~t the presen~
,invention may be adapted~ where desired, for use in other
18 ¦housings ~or electrical distribution appliancee, such as elec
lg trical junction boxes, 1ush type boxes~ etc. Accordingly, when
20 ¦used herein, the 'cerm "electrical outlet box~' is i:ntended to
21 ¦embrace such add~t~orlal stxuctures~ ~
: ~ 22 ¦ Also, although the present. invention is described
23 !~particular re:ference to an electrical outlet box foImed from a-
~oldable plastic material and to insulated electr~cal power cab~e
.;having a~ oval Jacket o~ a molded pl~stlc composition which i5
26 ' soft and readily de~ormable~ known in the art as "RO~ X" cable,
27 ;the pxesent invention may be adapted for use in an electrical
28 outlet box ormed from a metallic material7 in which case
29 it will be understood that either the aforesai~ "RO~X" cable
~' 3~ or the helical ~etal jacketed cable, ~nown in the art as '`BXI~'
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1 cable, may be used. Accordingly, the term "electrical power cable"
2 is intended to embrace both plas.ic and metal jacketed cables.
3 It will also be understood that although the present
4 invention is described with respect to rectangularly-shaped
electrical outlet boxes, the invention is equally applicable
6 to other conventionally shaped boxes, including round boxes.
7 : i
2. Description of the Prior Ar~
9 It is conventional for electrical outlet boxes to
have a number of ~able entry ports in which a panel or closure
11 member normally substantially closes the port aperture and is
12 removed, or "knocked-out", to permit passage of electrical
13 power cable into the box.
14 As previously known, however, electrical outlet box
lS ."knockouts" have been disadvantageous from several standpoints. I
16 Thus, removal or deflection of the "knockout" from the port
17 has heretofore required the use of a separate tool, such as
18 , a screwdriver or ha~mer or the like, resulting in a time-
19 ¦I consuming two-step operation in order to insert the cable into
20 !¦ the box. Also heretofore, the port aperture and the closure
21 ¦I panel have been o a single fixed size, usually to accommodate
22 ~ the largest size standard electrical power cable possible
23 ¦, under t'le applicable electrical code regulations, such that,
24 l upon removal of the closure panel, there is a substantial gap
25 ~ be~ween smaller-sized standard power cables and the rim o~ the
26 aperture, which subjects the installation to th~ aforementioned
27 haza~ds of debris collection and fire spread. I
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2~ '; In some applications, it also has been found that the
29 connection between the conductor ~ires of the cable and the
electrical appliance may be stressed or dailgerously loosened
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l by forces exerted on the cable or wires at other locations after j
2 installation. In addition, during construction of the wall
3 structure in which the outlet box is installed, the cable
; 4 conventionally is inser~ed through the cable entry port af~er
5' the box is mounted ln place, but the electrical appliance
6; may not be connec~ed to the cable and installed in the outlet
box until after the wall structure is secured in place. The
8 cable is thereby susceptible to accidental removal from the
g cable entry port before it is connected to the appliance,
and a significant, further time-consuming effort may be required
11 to reinsert the cable into the box.
12 In Qrder to fi~edl~ retain the cable in the box for
preventing such stressing on the connections or or preventing
~; 14 removal from the knockout window, clamping devices have been
; 15 previously developed or proposed, which are adapted to be
16 t secured in or adjacent each knockout window opening and to grasp
17,, the cable firmly for preventing withdrawal from the box. In
18 1I fact, such clamping devices are presently required by the
19 1! National Electric Code for multigang boxés and or so-called
20 j "old work" boxes. -
~' 21 ¦ Heretoore, however, most cable clamping devices have
1 22 I been formed as independent structures which have to be fabricated
23 ¦ separately from the box itsel, in relativèly complicated
24 il structures, such as shown in U. S. Patent l~os. 3,788,5~2 issued
25 ! to Sw2nquist, and 3,493,205 issued to Bromberg. These structures
26 involve sub~antial fabrication costs over and above tho~e of
27 making the box alone. In addition, slnce clamping devices have
28 to be affixed to the box, they also entail additional installa-
29 tion time and consequent labor expense. Moreover, in order to
be fixedly secured in the knockout window of the box, the
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1 engaging means for the separate clamping device must be propor- i
2; tioned to fit the particular configuration or the knockout window'
3 Thus, unless all knockout window apertures are standardized in
4i size and shape, numerous different sized and/or shaped devices
are needed, thereby greatly increasing the costs of manufacture,
6 inventory and installation time.
7 Altho~gh a metal electrical outlet box has been
proposed in which a cable clamp is formed integrally with the
g box structure, such as ~. S. Patent No. 3,112,938 issued to
I- P. Karlin in 1963, the clamping structure there proposed
ll does not automatically grasp nor resistingly bear a~ainst
12 the installed cable and several manipulative steps with separate ¦
13 tools are necessary in order to assemble the cable port closure
14 structure into a clamping position. Thus, the Karlin structure
is not self-opening nor self-clamping nor self-adjusting.
16j- Moreover, the Karlin ?atent 3,112~938 s~ructure is disadvantageouc
17i since it is possible to erect Karlin's port structure with too
18 ¦ larve of a space between the cable engaging edge of the port
l9 structure and the cable, so that cIamping either is not
effected at all or necessitates more manipulation to es~ablish
21 the proper spacin~ in order to obtain a clamping action.
22 ¦1 A thermoplastic electrical junction box with an
23i! intégral locking and sealing structure also has been proposed
24 ¦1 in Swiss patent 349,319 lssued to F. Meili in 1960. In that
25 1 patent, the entry ports of the box are nor~ally closed by
26 knockout or cut-out covers which, when removed in the conventional
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27 ~anner, leave a circular rim OL slightly smaller diametex than
23 ' that of the port aperture, which is inclined inwardly of the
~' 29 aperture to form a relatively rigid and relatively sharp circular;
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inner edge. Thermoplastlc insulating pipe for carrying
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1 electrical conductor wires is formed with transverse cuts in the
2 surface thereof and then inserted into the box aperture, whereupor ;
the aforesaid relatively sharp inner edge of the aperture rim
4 ' enters the cu~ in the manner of a barb to both seal and lock
5 ~ the pipe within the aperture against reverse outward ~ovement. ¦
6 As in the Karlin U.S. patent, 3,113,938, the lg60 Swiss patent
7 349,319 is therefore not self-opening and is not self-cla~ping ¦ -
8 as the structure does not aueo~atically grasp nor deflect
g laterally so as to resistingly bear against the installed pipe.
The Swiss patent's entry port structure is aiso not self-adjusting
11 to difIerent sizes of pipe and is otherwise disadvantageous since
12 the require~ent for cuts in the surface of the installed pipe
13 would be difficult to obtain in conventional metal jacketed cable
14 and unacceptable in conventional insulated plastic jacketed cable.
Finally, Swiss patent 459,323 issued to A. Grossauer in
16 ! 1968 discloses an injection-molded plastic electrical ~unction
17 1'l box having entry ports for electrical conduit piping w'nich
18 j include relatively thin tongues molded integrally with the box,
19 ~¦ which are spaced radially about the ri~ of the entry aperture and .
20 1¦ extend in the plane of the aperture. The entlre box is covered
21 ¦I with a sheath of rubber or plastic, including the entry ports~
22 ll Although this patent indicates that the tongues clamp tightly
23 ll against the conduit piping when tbe latter is a~tempted to be
24 l, ~ithdrawn, the tongues are said to be relatively thin and are
25 ' formed in the plane of the aperture and therefore very lit~le
26 cla~ping strength is availablé due to the large amount of
27 deflection required to pass a conduit through the aperture.
28 ' Also, due to their location and orientation in the plane of the
29 aperture, it is believed that the tongues would be easily broken
30 upon application of a reverse outward force on the conduit and,
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l at best, only a small range of different-sized cables could be
2 accommodated by any one length of tongue. Also, the provision
3 of a rubber or plastic sheath enveloping the entire box in
4 order to close the conduit entry ports is believed to be
5 , impractical and tends to disguise their location, making instal-
6 lation o the conduit more difficult.
8 3. Objects of the Invention
g It is therefore an object of this invention to provide
a new and improved electrical outlet box.
; 11 Another object of this invention is to provide a new
12 and improved electrical outlet box having a novel and improved
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13 cable entry port structure.
14 Another object of this invention is to provide a new
and improved electrical outlet box which facilitates entry and
16 retention of electrical power cable in the cable en~ry ports.
17 Another object of the present invention is to provide
18 ~I new and improved cable clamp means for electrical outlet boxes
19 ¦, and the like,
20 ¦ Another object of this inven.ion is to provide a
21 ¦ novel and improved cable entry port structure for an electrical
22 , outlet box which is self-opening by manual ~orce of the end of
23 il tne electrical power cable against the port structure.
24 l~ Another object of this invention is to provide a
25 !~ novel and improved cable entry port structure for an electrical
26 outlet box which is self-clamping against removal of the
27 electrical power cable from the entry port.
28 ; Another object of this invention is to provide a novel
29 and improved cable entry port structure for an electr~cal outlet
box which is self-adjusting to different sizes of electricai
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1 power cables passing into the box chamber.
2 Another object of this invention is to provide a novel ¦
3 and improved cable entry port structure for an electrical outlet j
4 box which is self-locating, such that the electrical power cable
5 ! is installed in the entry port aperture at the same predeter~ined ¦
6 position, regardless of size. ~ -
7 Another object of this invention is to provide a noYel
; 8 and improved cable entry port structure for an electrical outlet ,
9 box which can be relatively easily and inexpensively formed 2S ¦ -
an intevral part of an electrical outlet box, and yet which
' 11 is unexpectedly durable and strong in use.
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12 Another object of this invention is to provide a
13 novel and improved cable entry port structure for an electrical
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14 outlet box which includes frangible closure means substantially ' -
15 ' preventing access into the box through the cable entry port
16 structure and adapted to rupture when subjected to a predetermine~
17 , force to permit entry of the electrical power cable into the box
18 ¦ hamber
19 1', Another object of this invention is to provide a new
20 jl and improved electrical outlet box having a novel and improved
21 ¦~ cable éntry port structure which eliminates or overcomes the
~2 ¦I disadvantages of previously known cable entry ports for electrical i
23~¦1 outlet boxes or the like.
24 ll Another object o the invention is to provide a
25 !~ novel and improved cable entry port structure 'or an electrical
6 ' outlet box which enables the cable to be quickly and easily
27 ~ installed and-automatically clamped to the wall structure o
28 the box in the installed position without the use of tools or
29 parts separate rom the cable and box.
Objects and advantages of the invention are set forth ,'
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~ '','. ' ' ' 1,1 ' in part herein and in part will be obvious herefrom, or ~ay be
2 learned by practice with ~he invention, the same being realized
3 and attained by means of the instrumentalities and combinations
4 ; pointed out in the appended claims. I
The invention consists in the novel parts, constructions,
6 arrangements, combinations and improvements herein shown and
described.
g SUlDM~RY OF THE INVENTIO~ i
Briefly described, the present invention is directed
1~ to a new and i~proved cable entry port structure for an electrical
12 outlet box which facilitates both entry of the electrical power
13 cable into the box and subsequent retention of the installed
14 cable within the box chamber. , -
lS ' As preferably embodied, the cable entry port structure I -
16 of the invention is formed as an integral part of the wall
17 '' structure of the electrical outlet box and comprises one or more
18 , clos~lre panels, each of which are mounted adjacent the rim of
19 1¦ the port aperture along one edge portion only of the panel,
20 1l the remaining portion of each panel being free and extending ¦ :
21 1¦ substantially across the aperture in a direction angularly
22 11 inwardly from the plane of the aperture. The closure panels are
23 ¦1 each either hingedly mounted to the rim of the port aperture or
24 11 are suficiently flexible and resilient such that the ree end
25 1l portion of each panel is deflected away from the opening upon
26 manually pushing the end of the cable into the aperture, and
27 ' thereafter resistingly bears against the installed cable~ i
28'' In another preferred e~bodi~ent of the inventionj
29 each o the clo9ure panels are tapered so as to have increased
thickness at the base, in which case the panels are self-clamping
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1 against removal of the installed cable from the aperture, and
2 preferably also include supplemen~ary cable gripping projections ' -
3 bn their outwardly facing surfaces.
, Also as preferably embodied, access to the box through ¦
the cable entry ports is substantially prevented by a frangible
6 closure member, which may be either a thin web joining the free
7 end of a single closure panel to the wall structure of the box
~ or joining the free ends o two or more panels together, or as
g a separate conventional knockout panel frangibly interconnected
to the rim of the cable entry aperture.
11 It will be apparent from the foregGing general descrip- '
12 tion that the objects of.the invention specifically enumerated
13 herein are accomplished by the invention as here embodied.
~4 Thus, it has been found that one or more closure
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" 15 panel members may be ormed integrally with the wall structure
of an electrical outlet box adjacent the rim o the aperture
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17 orming the cable entry port and extending angul2rly inwardly
~; ~ 18 j therefrom. It has also been found that one or more of the a ore-
;` l9 li said closure panel members may be surprisingly easily and rela-
` 20 1~ tively inexpensively integrally molded into a mDldable electrical
21 ,j outlet box,
22 ~l By providing the angularly inwardly extending closure
23 j panel members wi~th free in~er end portions and also with both
4-1i ~flexibility and resiliency, either by means of the material of
2g ,' const~uction and/or the proportions thereof or by mounting the
`i, 26 panel members to the wall structure of the box by means of a
; 27 living hinge, the closure panels will deflect away rom the
28 aperture to permit the electrical power cable to enter into the
~1 29 box chamber and will thereafter resistingly bear against the
~ 30 cable so as to maintain an opening which is always essentia;ly
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l equal in size to the cross-section of the installed cable. It
2 has also been unexpectedly found that this port closure structure '
3 may be deflected with no more force than is developed by simply
4 manually pushing the end of the cable against the closure panels,
including, in particular, the ~foresaid soft plastic jacketed
6 "ROMEX" cable. As a result, the port closure structure of the
invention is seLf-opening since no separate ~ool is required to
8 open the port closure panels. In addition, the inwardly angled
g closure panels automatically self-adjust the size of the port
opening to that of the installed cable, thereby at 211 times
11 minimizing debris collection in the box and the aforementioned
1~ potential ha7ard of fire-spread,without being broken away. A
13 fur~her advantage found from this port closure structure where
14 the closure panel or panels angle inwardly from the plane of
the aperture is that it serves to automati,ally positively locate !
16 ~ the electrical cable at a predeter~ined position for entrance
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17 , into the box chamber.
18 1 It has also been found, in the embodiment of the inven- ¦
19 ! tion where the closure panel members are tapered so as to be
20 11 thicker at the base thereof adjacent the rim of the cable entry
21 port structure, that the camming action of the panel members
22 against the cable upon the application of a reverse out~ard force
23 lj to the cable is unexpectedly and surprisingly strong, such that
24 1 the cable is securely and positively clamped against reverse
outward movement without the need for any separate or external
26 parts. In particular, it has been found that although the
27 closure panel members are molded from plastic th~ aforesaid
28 structure resistingly bear5 against the soft plastic jacketed
29 electrical power cable with such force that it indents the outer
surface o the jacket, and provldes a surprisingly strong ànd
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1 effective clamping action against such cable.
2 Moreover, by formin~ supplementary, sharp-ed~ed rib-like
3 projections on the outwardly facing surfaces of the closure panel
4 members, provision is made for~grasping a full range of sizes
; of cable up to the maximum size cable that will be accepted
6 by the aperture. Thus, there is no need for abricating separate !
cable clamp devices for different sized cables, or providing
8 separate boxes for use with different si~ed cables or conduit.
~- 9 It has also been found that by recessing the base of
- 10 the closure panel members from the rim of the cable entry port
11 apertùre, in addition to permitting the panel members to deflect -
;12 and clamp against cables equal in si~e to the size of the aperture
13 without breaking, the closure panel members may be formed
~ 14 integrally with the wall structure of the box along with the , -
;; 15 usual cable entry port "knockout" panels frangibly removably ',
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16 attached across the cable por~ aperture.
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17 , rt will be understood that the foregoing general
18 j descrip~ion and the follo~Jing detailed description as well are
19 1 exemplary and explanatory or the invention but are not res~rictive
20 ¦' thereof~
2LIi The accompanying drawings, referred to herein and
22 iI constituting a part hereof, illustrate preferred embodiments of
23 il, the invention, and together with the description, serve to
24 e-~plain theq~principles of the invention.
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1 BRIEF DESCRIPTIO~ OF THE DRAI~INGS
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2 FIGURE 1 is a top plan view of an electrical outlet
3 box embodying the present invention, the view illustrating a
: 4l first panel member frangibly interconnected across each cable ¦
5 ! entry port aperture and an additional pair of tapered closure
6 panel members converging angularly inwardly toward one another
7 from opposite sides of the aperture for clamping an electrical
8 power cable inserted into the entry port against reverse outward j
g movement;
FIGURE 2 is an elevation view of one end wall of the
11 box shown in Figure l;
12 FIGURE 3 is a view along section 3-3 of Figure 2;
13 FIGURE 4 is a VieW along section 4-4 of Figure 2;
~' . 14 FIGURE 5 is a partial bottom plan view of the back or
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~` 15 botto~ of the box shown in Figures 1 and 2, taken as indicated
i: 16 at 5-5 of Figure 4;
-.~ . 17l" FIGURE 6 is a section view similar to that shown in ¦ .
8 li Figure 3, illustrating the opposed tapered and angled closure
: 19 ll panels in deflected position, and resistingly bearing agains~
: I :. 20 the installed cable;
~ 21 FIGURE 7 is a fragmentary perspective view of an elec-
: 22 trical outlet box constructed ln accordance with another e~bodi-
23 ¦¦ ment of the present invention, wherein the cable entry port
24 1! structure includes only the opposed tapered and algled closure
25 !I panel me~bers as shown in Figure l,the convergent inner free
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1~ 26 ends being joined by a frangible web;.
27 FIGURE 8 is a view along section 8-8 of Figure 7;
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. 28 FIGURE 9 is a view along section 9-9 of Figure 7; ~,
29 FIGURE 10 is a section view similar to that shown in
~;~`. 30 Figure 8, showing the closure panel members with supplementary
31 &ripping projections;
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1 FIG~E 11 is a frag~entary longitudinal sec~ional view,
2 partly in elevation, similar to that of Figure 9, of an
3 electrical outlet box constructed in accordance with a still
4 i further embodiment of the invention, wherein the opposed conv2rg- ¦
ing closure panel meMbers are of essentially unifor~ thickness
6 and are joined at their inner convergent ends by a frangible
7 web;
8 FIGURE 12 is a view along section 12-12 of Figure 11;
g FIGURE 13 is a section view similar to that shown in
Figure 12, showing the opposed panel members deflec,ed from the
11 aperture and resistingly bearing against the installed cable; .l
12 FIGURE 14 is a view si~ilar to Figure 11, illustrating j
13 the opposed closure panel members joined by a frangible web at
14 their approYimate mid-sections only;
15 . FIGURE 15 is a fragmentary bottom plan view of an
16 : electrical outlet box constructed in accordance with another
17 , embodiment o the invention, ~herein a single tapered closure
18 I panel extends angular~y inwardly from one side of the cable entry
19 ¦! port aperture and is franglbly interconnected with the side
20 il wall of the box adjacent the wall in which the aperture is
21 ~ formed;
22 ! FIGURE 16 is a ~fragmentary sectional view partly in
23 1' plan, of the:structure of Figure 15, illustrat~ng the closure
24 ' panel in deflected position and resistingly bearing against the
installed cable, the view also illustrating supplementary
26 gripping projections on both the panel and the wall structure
27 ~for grasping the installed cable;
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;: 28 FIGURE 17 is~ a rag~entary elevational view of an
29 electrical outlet box constructed similar to that shown in
Figures 7^10, wherein a pair of opposed tapered and angled
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l closure panels converge ~oward one another from the longitudinal ~i
2 side ril~s of the cable entry aperture and a third tapered
3 closure panel converges angularly downwardly from the box wall
4 ' structure toward the convergent inner ends of the pair of
opposed closure panels;
6 FIGURE 18 is a view taken along lines 18-18 of
Figure 17;
8 FIGURE 19 is a vlew taken along lines 19-l9 of
g Figure 17;
FIGURE 20 is a fragmentary perspective view of an
ll electrical outlet box constructed in accordance with a further
12 embodiment of the invention, wherein a group of four tapered
13 closure panel ~embers each converge angularly toward one another ¦
14 and a center ~rangible web joins one opposed pair of converging
15 ! panel members, the cable entry port aperture and closure
16 structure being located in an angled corner of the outlet box
17 ,. joining the bott~m wall and the ad acent front-to-rear wall;
18 1l . FI~URE 21 is a bottom plan view of the diagonal wall
19 ~l portion o Figure 20 joining the bottom wall and the adjacent
20 j front-to-rear wall; .
21 FIG~RE 22 is a sectional view, partly in elevation,
22 taken along line 22-22 o~ Figure 21;
23 il . FIGURE 23 is a fragmentary cross-section view, similar
24 ,I to Figure 8, o a further embodiment o~ a cable entry port
25 ; structure for an electrical outlet box constructed in accordance
26 with the invention, illustratin~ ~'ne pair of opposed tapered
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27 and converging closure panel members each mounted at one end
28 adjacent the rim of the cable entry aperture by a live, integrally
29 molded-in hinge;-,
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IGU~E 24¦is a fragm~ntary -ross-section ViPW similar
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1 to Figures 15-16 of another embodiment of a cable entry por~ j
2 structure for an elec~rical outlet box constructed in accordance j
3 with the invention, wherein the closure panel is mounted at the
4 ' base thereof by means of a live, inteOrally molded-in hinge
located relatively inwardly of the wall structure of the box
6 containing the cable entry port aperture, the view also illustra-
7 ting a plurality of rib-like gripping projections forming a
8 serrated outwardly facing surface on the closure panel; and
qcl~actnt fl~ 16
9 FIGUP~ 25~is a similar fragmentary cross-sectional
view of the embodiment shown in Figure 24 illustrating the
11 closure panel member in a defiected condition and in cammed,
12 clamping engagement with an installed electrical power cable.
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18 ; : DESCRIPTIOI~ OF THE PREFE~RED EMBODIMENTS
19 ! Referring ~enerally~to the embodiments of the inven-
20 ¦j tion shown in the accompanying drawings, wherein like reference
Zl~ numerals refer to like parts,~there is illustrated an electrical
22 Jj o~utlet box, indicated generally by reference numeral 1, which
23 1l advantageously may be~of~a generally~rectangular:shape and
24 l~includes a bottom wal~l 2,~a~pair of~opposed end walls~3, 4, a
25 ' pair~of opposed side walls ~5,~ 6 extending between the;aforesaid
;26 ~jend walls, eac~ of the end~and side;walls terminating in a
27 continuous~front edge~7 lylng in a frontal plane which is
28i ~parallel to the bottom wall 2 and defines the front opening 8 o
29 ¦the box. Outlet box 1 also advantageously includes an opposed ¦ .
pair of conventional mounting post members 9 adjacent each of the ' -
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~- end walls 3, 4 for securing an electrical fixture to the box, as is well
known in the art. Advantageously, each of posts 9 includes an unthreaded
borehole 9a (see Figure 1) for slidably receiving a unting clip (not
shown) in each of the posts adjacent the borehole for quick fastening of
a threaded screw thereto, such as is more fully described in U.S. Patents
3,955,463 and 4,105,862.
As previously mEntioned, it will be understood that, although
a rectangular outlet box is illustrated in the drawings and referred to in
describing the invention, the invention is not limited to any particular box
configuration, and its application to boxes of other configurations, such
as round boxes, will-be readily apparent to those of ordinary skill in the
art. Also, it will be und~rstood that box 1 may be suitably adapted for
attachment to a stud, to wallboard and the like in any desired fashion.
However, for convenien oe in describing the present invention, such mounting
means are not shGwn on box 1.
Referring now more particularly to Figures 1-6 of the
accompanying drawings, there is illustrated a first embodiment of cable
entry port means constructed in accordance with the invention, indicated
generally by reference number 10, which is adapted to be formed integrally
with the wall structure of electrical outlet box 1, and which is self-
clamping against removal of a cable installed in the entry port.
In accordance with the invention, cable entry port means 10
includes a pair of closure panel members, both indicated by reference
- nu~ber 14, which depend from opposite sides of the rim of cable entry
apertures, preferably formed in end walls 3 and 4 of outlet box 1, and
converge angularly inwardly t~ard
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1 each other, terminating in free ends 25 separated by a distance
2 which is preferably less than the narrowest dimension of the
3 electrical power cable to be inserted into the box. The cable
4 entry apertures are indicated generally at 22 and provide
access for admitting an electrical power cable to the interior
6 of box 1.
7 . . As here preferably embodied, each closure panel 14
8 extends from a portion of its corresponding end wall 3 or 4,
~` 9 so that its outwardly facing surface forms an angle, indicated
at oC in Figure 1, of about 45 with end walls 3, 4. In addition,
11 the angle, ~ , formed by the inwardly facing surface of each
; 12 panel member and the adjacent end wall 3 or 4 is, advzntageo--sly,
~ 13 slightly smaller, preferably on the order of about 35~-40~, than
`~ 14 that made by its outwardly facing surface, so that the panel
:~ ,
members 14 each taper slightly towards their convergent inner
16 free ends 25, providing a generally rigid portion where the panel
17 is attached to the end wall at the rim of the aperture, while also
18 l providing flexibility at the COnVergent inner free ends 25,
19 ,~such that the panel members 14 deflect laterally away fro~ one
20 jl another upon pas9age of the cable into the aperture 22.
21 ¦¦~ Also as preferably embodied, and as is more fulIy
22 i described hereinaf~er, closure panel members 14 are ormed from
23 ,, a material having suitable resiliency such that, upon being
24 i deflected laterally away from one another and also relative to
aperture 22, the free end portions thereafter resistingly bear
26 against the installed cable. . -
,~ .
27 For additional flexibility, the thickness of the free
28 end portion of each closure panel 14 advantageously may be reduced
29 by about half, as hy notch 24 preferably formed at about 1l16"
to about 1/8" from the end edge 25 of each panel member LO provide
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1 a ~enerally flexible and resilient end to grasp a cable. Thus,
2 the end edge of each panel 14 is much more flexible than the
3 rest of the panel 14 so that relatively thin cables (such as
indicated in phantom at 26 in Figure 3) can be inserted between
5I the inner grasping edges without ca~sing the cable to bend.
6 ~oreover, the reduced thickness inner end edges enable secondary j
grasping points to be provided with substantial rigidity while
8 the thin ends move out of the way of thicker cables, as will be
g' described more fully below with reference to Figure 6.
Accordingly, when electrical power cable 26 is inserted
11 into an open cable entry aperture 22, the cooperating opposed
12 tapered and angled panel members 14 will resiliently flex
13 inwardly of the box to permit relatively easy insertion of the
14 cable and thereafter resistingly bear against the installed
cable. Thereafter, upon application of a reverse outwardly
16~ directed force on the cable, tending to remove the cable from
17 !~ opening 22, the convergent inner free ends 25 of panels 14 are
18 i urged by means of a caFming action progressively more tightly
19 ~' against the cable, into increasing gripping engagement therewith,
thereby effectively clamping the cable against reverse outward
21 movement.
22 . It has been fo~nd that, where the plastic ~acke~ed
23 "ROMEX" cable is used, the inner ends 25 of panels 14 resistingly
24 ¦~ bear against the cable with sufficient force to indent the
cable jacket, which force remains even at high temperatures, on
26 the order of 90C., enabling the aforesaid camming action to be
27 obtained under high temperature conditions for both plastic
28 and metal jacketed cable. To the foregoing end, the free end
29 edge 25 of each closure panel 14 advantageously is formed with a
' generaily sharp corner, facing the other panel in each cooperating
,
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pair of panel me~bers to provide a rib-like structure for wedyirlg into
cable 26. In addition, the distance between such cooperating sharp edges
is advantageously proportioned to accommodate the variety of thicknesses
for the cables which may be received within the cable entry apertures 22
in box 1. m us, for example, for the usual residential single- and double-
gang outlet boxes, adapted to acccm~odate AWG (American Wire Gauge) #14,
#12 or #10 wires, the spacing between the inner end edges 25 of panel
members 14, indicated at d in Figure 1, is advantageously dimensioned at
about 0.15 inches.
~en a relatively large diameter cable, indicated at 27 in Figure
6, is inserted into the cable opening 22, the cooperating pair of closure
panels 14 spread apart in a generally elliptically-shaped curved
configuration,-as shown in ~igure 6, since they are essentially cantilever
beams. As a result, the end edges 25 of closure panels 14 may be unable
to grasp the cable. merefore, in accordance with the invention, supplementary
gripping means is provided for grasping and clamping the cable agalnst
reverse outward movement. To this end, secondary grasping means, in the
form of a rib-like projection, indicated at 25a in Figure 3 and formed
by notch 24, are preferably formed on each panel 14, recessed frcm the
- 20 end edge 25 to grasp the insulation on thick cable 27 for preventing
withdrawal thereof. M~reover, projections 25a can be stiffened, or
buttressed, by providing any desired thickness to the portion of each panel
; bet~een the notch 24 and the wall portion to which the panel is attached,
to ensure a firm grasp on such large cables. Alternatively, paneI 14
~- may be formed with rib-like projections, such as shown at 35 and described
below with reference to Figure 10, either instead of or in addition to
the notch/edge configuration 24, 25a.
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l As preferably embodied, closure panel members 14
2 extend lengthwise, from a point just in front of bottom wall 2
3 of outlet box l, as described more fully hereinafter with
4 respect to Figure 5, to a point forward of the front edge of
aperture 22, as shown in Figures 2 and 4. Accordingly, if
6 cable 26 is inserted into opening 22 frem behind box 1 so that
7 it curves towards the front of the box, as indicated in phantom
8 in Figure 4, the cable will still be retained in the box by the
g portion of the closure panel members 14, which lies forward of
the front edge of opening 22.
11 According to the invention, as illustrated in Figures
12 1-6, cable entry port structure 10 may advantageously be
13 adapted to permit the usual "knockout" closure panel to be for~ed
14 across each cable entry port 22 for preventing fire spread as
well as preventing any debris from entering any cable entry
16 port that is not utilized for allowing access into the box
17 for an electrical power cable. To this end, each closure panel
18, member 14 is preferably attached to its corresponding end wall
19 , portion 3,4 by a projection, or base portion, 14a, as best sho~m
20 ~ in Figures 1 and 3, which is slightly recessed from the rim of
21l aperture 22 and spaces the panel 14 inwardly from its associated
22 ! end wall. In this way closure panels 14 themselves are suffi-
23 1I ciently spaced inwardly and laterally of the ri~ o aperture 22
24 Ij to accommodate the usual knockout closure panel, indicated at 28, ¦
which is removably attached across each cable entry port 22.
26 Advantageously, knockout panels 28 are attached to end wall
~ , .
27 portions 3, 4 by frangible web members 30, with shoulder 32
28 formed on bottom wall 2 to facilitate removal, similar to the
;; 29 knocXou~ panel means disclosed in U. S. Patent 4,007,852, assigned
to the same assignee as the present application and which patent
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is of interest. However, other conventional knockout wind~w closure
panels may be used, the structure of which will be apparent to those of
ordinary skill in the art.
As preferably embodied, the side edges of knockout panel 28 are
chamfered, or beveled, slightly, as shcwn in Figures 1 and 3, in order
to permit the-portions of the ld which form knockout panels 28 and
closure panels 14 to be proportioned for sufficient structural strength
to withstand the stresses generated during molding. Advantageously,
shoulder 32 may be provided by forming bottGm wall 2 with a generally
; 10 thickened portion as shcwn in Figure 4. In addition, it will be found
that the base portions 14a associated with the panels 14 ~hich are
; positioned adjacent the screw-mounting post 9 may, in part, extend
directly frcm the post and those portions 14a associated with the panels
14 which are positioned adjacent a side wall portion 5 or 6 may, in part,
extend directly from that side wall portion.
; Also as preferably e~bodied and as shcwn in Figure 4, the bottom
edges of closure panels 14 are formed separate from bottom wall 2 to enable
them to be free and act indepPndently of the bottom wall. To this end,
:~ the portion of the injection mold which forms the exterior surface of
bottom wall 2 may be formed with projections proportioned and positioned
to correspond to the cross-sectional area of each panel 14, formlng holes
21 which éxtend oompletely thrcugh bottam wall 2 to defLne the bottom
edge of each panel 14. m e bottom edge of éach panel is thereby visiblP
; ~ frcm the botb~m of box 1 through slots 21 as shcwn in Figure S. In this
context, it will be understood that by forming bottom wall 2 with a
thickened portion, as shcMn in
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1 Figure 4, the bottom wall will be sufficiently strong to with- j
2 stand all the stress, impact, etc. required by Underwriters'
3 Laboratories and any Code writing associatlon.
4 It will be understood that the present invention is
not limited to any particular size of electrical outlet box or
6 cable entry port structure and the following dimensions are given¦
7 as an example of a box incorporating the invention, from which
8 other equivalent dimensions will be apparent to those of
g ordinary skill in the art. Thus, it has been found in an
electrical outlet box molded from an injection moldable thermo- ¦
. I
11 plastic resin material, more fully described hereinafter, that
12 apertures 22 advantageously may be approximately one-half inch
13 (1/2") wide and one-half inch (1/2") long; the point of conver-
14 gence of closure panels 14 may be approximately three-eighths
inch (3/8") from the inside surface of end walls 3 or 4, and
16 panels 14 may preferably taper from a thickness of about 0.030"
17 (approximately 1/32") thick at their convergent inner free
ends to about 0.060" (approximately 1116") thick at their bases
19' adjacent the rim of aperture 22~
20,' The 1exible inner edge portions of panels 14 may range
21¦i rom about 0.030"-0.050" thick when formed of the aforementioned
22l thermoplastic material to provide the flexibility described above ¦
23~l with the thicknesses of the remaining panel portions determined
24 ,I by the angles ~ and ~ if they are formed without secondary
grasping means or projections 35. However, if the panel is
26 ~ormed with the notch and edge 24, 25a, the panel portion between
27 the notch and the point of attachment may be made in a somewhat
2~ greater thickness, i desired.
29 Re~erring now more particularly to Figures 7-9 of the
.accompanying dra~7ings, there is illustrated a preferred alternate
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1 embodiment of the electrical outlet box of the present invention,
2 wherein the cable entry port means is self-opening, such that
3 a conventional electrical power cable ~ay be installed without
4 the use of separate ~ools such!as a screwdriver or the like.
To that end, as best seen in Figure 8, the adjacent
6 convergent inner ends 25 of closure panel members 14 are joined
7 by a frangible web member 34, which is adapted to be readily
8 broken by manually forcing the end of a conventional plastic or
g metal jacketed elect~ical power cable against the web. Although
web 34 is shown extending along the entire length of the
11 convergent inner ends of panels 14, alternatively, and with
12 equally satisfactory results, web 34 may extend between the
13 convergent ends 25 of panels 14 along only 2 short portion of
14 their length, on the order of approximately 1/8-1/4 inch, pref-
erably at the mid-section thereof, in a manner similar to that
16 shown in Figure 14.
17 Web 34 advantageously is attached to the free end edges
18l; 25 of panels 14 by additional intermediate web sections 36 which
19,~ are recessed back from the oppositely dis~osed pointed edges
25a which project to~7ards eac~ other in each cooperating opposed
21 pair of panels 14. In this way, if web 34 is complately removed
22 (as will be described ~ore fully below), the remnants of web
23' portions 36 left on closure panels 14 will be spaced from
24 . grasping edges 25a so as not to interfere with their cable grip-
ping function.
26 As preferably embodied, each cable entry aperture 22 is
27 formed with a component portion, designated at 22a, exter.ding into~
28 bottom wall 2. The shape of aperture portion 22a is generally
29 V-shaped and conforms to the cross-sectional configuration
provided by the closure panel members 14, as indica~ed in Figure 7,
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1 In this way, outlet box L, panels 14 and frangible webs 34 and
2 36 can be integrally formed from a moldable plastic material
3 and the bottom edges of panel members 14 can be formed
4 separated from bottom wall 2 to provide freedom for
each panel 14 to flex independently of bottom wall 2 when cable
6 26 is inserted therebetween. .
7 ~ Also, as preferably embodied, the generally V-shaped
. 8 space between closure panels 14, which opens in a direction i
g perpendicular to the frontal plane 7 of the box, is at least
- 10 substantially closed by a third closure panel 38 extendingll transversely and closely adjacent to the frontmost edges of the
12 angled closure panels 14. Advantageously, a reiniorcing rib
13 or strut 38b is formed to extend between the top of port clo~ure ¦
~- 14 panel 38 and the inside surface of end walls 3, 4.
;
~ lS Of course, the front-facing edges of panel members 14
,,
~: ~ 16 are formed independently of third closure panel 38 and as
17 previously mentioned, the bottom-facing edges of panels 14
~` 18, are formed independently of the bottom wall 2 of the outlet box
(: 19l~ 1, as shown in Figure 9, to permit deflection of panel m~mbers 14.
.~ 20 I,i To thi5 end, the innermost surface of web~34 preferably ter~inatec
- 21 ¦l even with the backwall upper lip, indicated at 2a, and the
22 ,l edges of rigid closure panel 38 are proportione~d to correspond
~ ~ 23 ! to the generally V-shaped contour of the opposed facing surfaces
:~ ~ 24 ',; o panels 14 and web 34, or they may be slightly spaced therefrom,
: 25 as indicated by the letter s in Figure lOo In this way, ~he
26 appropriate mold elements may be accommodated for.forming the I -
~c
-~ 27 various surfaces and edges of panels 14 and 38, webs 34, 36 and
28 bottom wall 2 in a two-part molding machine,
29 Third closure panel 38 serves not only to prevent fire
30 spread and debris from falling into the interior of box l when
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l web 34 is not opened bu~ also to prevent a cable 26 from
2 slipping forward, i.e. mo~ing laterally towards the front of
3 ~ox 1, out of grasping engagement with the edges 25 of panel
4 members 14. T~us, each cable entry port which is not utilized
will remain substantially closed by the combination of closure
6 panels 14, webs 34 and 36 and closure panel 38.
7 Referring now more particularly to Figure 10, as
8 previously mentioned, the supplementary cable gripping means
g of the invention may also include the formation of one or more
additional relatively sharp-edged rib-like projections 35 extend-'.
ll ing along the length of the outwardly facing surface of each ~ -
12 of panel members 14. Advantageously, projections 35 are located j
13 about l/16" to about l/8" from edge 25a, and enable the panels
14 14 to grasp thick cables despite substantial bending such as
l; shown in Figure 6. Furthermore, in order to form projections 35 ¦
16 by a two-part molding machine as described above, rigid closure
:
17 panel 38 is preferably formed with corresponding notches,
~` 18 i indicated at 35a, in registry with projections 35.
g l~ As previously mentioned, as preferably embodied
20 ! frangible web 34 is readily pierceable by the force developed
21 I upon manually pushing the end of an electrical power cable agains
~ 22 the web, so as to thereby be self-opening. To that end, web 34
; 23 , may advantageously be formed with a reduced thicknecs center
2~ portion, indicated at 34a on Figures 8 and lO. It has been
~;~ 25 ~ound that when formed rom a thermoplastic resin materia~ as is
26 more fully described hereinafter, web 34 will withstand a force
;~ ~- 27 of 10 pounds and yet be readily pierceable merely by pushing the
28 end of an electrical power cable thereagainst, where the reduced
~;~ 29 thickness center portion is approximately 0.010" thick and the
3d .web increases in thickness to approximately 0.020" thick at~ its
,
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; 1 attachment to webs 36, the latter also approximately 0.020" thick.
2 Alternatively, it will be understood that if desired
3 frangible web 34 ~ay be formed somewhat thicker so as to be
4 rupturable only with the aid of a separate tool such as a
screwdriver or the like. Accor~ing to one such embodiment, web
6 portions 36 may be formed relatively thin so tLat web 34 resembles
a narrow knockout panel which can be removed by pushing it
8 inwardly with a screwdriver or similar tool, thereby breaking
g the webs 36. Alternatively, the tip of a prying tool may be
inserted between the projecting end portion 38a of third panel
11 38 and the front-facing edge of web 34 to break webs 36 by
- 12 prying web 34 inwardly, using the edge of projecting portion
1~ 38a, reinforced by rib 38b, as a fulcrum. Thereafter, a cable
1~ may be reinserted into the space between the oppositely disposed
1~ lS convergent ends 25 of panels 14 which will grasp the cable, as
16 previously described
17 l~ It will be seen from the foregoing that the cable entry
18 i port means of the invention as preferably e~bodied is both
19 1' sel-opening and self-clamping. The port means is self-opening
~1~ 20 1 in that no separate tool such as a screwdriver or the like is
- ~ 21 ¦ required in order ~o break the frangible closure web 34. The
22 1l tapered closure panels are also self-clamping since, upon in~ard
23 ~1 movement of the cable into the box chamber, the angularly inwardly
i~ 24 ' directed closure panels are slightly spread apart and their
~ 25 resiliency causes them to resistingly bear against the
,~ 26 cable. Consequently, a reverse outward orce thereafter applied
27 to the cable causes the inner end portions of the closure
28 panels to be urged by means of a camming action progressively
~:.
29 more tightly against the cable, into increasing gripping engage-
-~ 30 mén~ therewith, thereby efectively clamping the cable
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against reverse outward movement.
It will alxo be seen that the cable entry port means
of the invention as preferably embodied is also both self-
locating and self-adjusting for different sizes of electrical
power cables passing into the box chamber. Thus, the provision
of opposed inwardly angled clo$ure panels serves to locate the
electrical power cable within the box at a predetermined,
consistent location, which is at the apex of the converging
panels, irrespective of the cable size. Also, the preferred
lengths and thicknesses of the closure panels, particularly
when formed from a moldable plastic material, as is more fully
.
described hereinafter, provide the panels with sufficient
flexibility and- resiliency so that they deflect laterally away
from the point of convergence, thereby permitting the panels
to adjust to the different cable sizes, and yet resistingly
bear against the cable in their deflected condition. By
recessing the base of the closure panels away from the aperture
rim, as best seen in Figures 3 and 8, cables having thicknesses
up to a thickness equal to the width of the entry aperture can
.
be accommodated with satisfactory results.
Referring now more particularly to Figures 11-14 of
the accompanying drawings, there is illustrated an alternative
embodimen~ of the invention, wherein the cable entry port closure
panels extend angularly inwardly from the rim of the port
opening and are self-opening for quick entry of the cable
therethrough, as well as self-locating and self-adjusting, but
provide only slight clamping action against the installed
-; electrical power cable. As alternatively embodied, the opposed
closure panels 44 are of a uniform thickness throughout which
,:
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is relatively thin, on the order of about 0.030" (appro~imately
1/32") thick, and the frangi~le connecting web 45 is on the
order of ahout 0.010" thick, as indicated at t on Figure 12,
when injection molded from a thermoplastic resin material, more
fully described hereinafter. In addition, the angle formed
between each panel 44 and the end walls 3, 4 to which each is
attached is preferably on the order of about 30.
Pigure 13 illustrates panels 44 in their deflected
condition and resistingly bearing against the installed cable,
indicated by reference numeral 460
Figure 14 illustrates at 45a a modification of the
frangible web joining panels 44, wherein the web is attached
to the clo~sure panels along only a short section of their length,
on the order of approximately 1/8 - 1/4 inch.
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1 In the embodiment shown in Figures 11-14, the inwardly
2 converging closure panels 44 have been found to be advantageous
~; 3 in use since, in a manner similar to closure panels 14, they flex
`~ 4 only a distance sufficient to permit the cable to pass through th2,
~ 5 port aperture, thereby maintaining a substantially closed opening I
- 6 even in use and hence minimizing debris collection and the hazard !
7 of fire spread.
8 Referring no~ more particularly to Figures 15-16 of
g the accompanying drawings, ther~ is illustrated a further
~` 10 embodiment of the invention, wherein the cable entry port means
~; 11 includes only a single closure panel member, indicated by refer-
12 ence numeral 50.
13 As shown in Figures 15 and 16, panel 50 is formed
14 integrally with end wall 3 at a point adjacent but recessed
from one longitudinally extending side rim of aperture 22 and
16 eY.tends angularly inwardly therefrom terminating in a free end
portion 51 adjacent the slde wall 6 ad~oining end -~all 3.
18 Advantageously, and as here embodied, panel 50 is tapered so as
19 to have increased thic~ness at the base 52 thereof adjacent the
20 ~ ,!rim of aperture 22, and is frangibly joined to side wall 6, by
21 'web 53 similar to any of the manners previously lllustrated and
22 described. ~Also advantageously, the outwardly facing surface
23 54 of panel 50 is provided ~ith a supplemental gripping project~on
24 35, as shown in panels 14 in Figure 10, and a~further gripping
;25 projection 55, similar in configuration to projection 35, is
26 provided on the inside surface of side wall 6 at the point
27 of the frangible attachment of panel 50 thereto. A rigid closure
28 panel 56, similar to panel 38 but formed in the general shape of
.~ ~ 29 a right triangle~ the hypotenuse of which extends generally
parallel to panel 50, substantially closes the right triangularly-
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1 shaped opening formed in the bottom wall 2 and facing the front
2 opening 8 of the outlet box.
3 It will thus be seen that, in a similar manner to that
4 previously described and illustrated in connection with the
inwardly converging pair of tapered closure panels 14 joined
6 by frangible web 34, and as illustrated in Figure 16, web 53 may
7 be broken by manually pushing the end of an electrical power
8 cable against panel 50, whereupon panel 50 will deflect laterally
g ~way from aperture 22 and thereafter resistingly bear against
the installed cable. Exertion of a reverse outward force on
l cable 26 thereafter causes panel end 51 and/or projections 35
12 and 55 to be cammed into progressively tighter gripping
13 engagement with the cable, thereby clamping the cable against
14 reverse outward movement.
15 ~ Although the embodiment of the invention in Figures lS-
16 16 is thus also self-opening and self-clamping, as well as
17 l~ self-locating and self- djusting to different cable sizes, it
18 1i will be understood that panel 50 need not be tapered and
19 I may be of substantially uniform thickness, similar to panels 44, ¦
20 j if clamping action is not required. .
I .
21 j It will also be understood that closure panel 50 may
22 , be spaced inwardly of its adjacent~end wall 3, 4 by a base
23 .I projection similar to 14a, as best shown in Figure 3, to permit
24 ,, use of a conventional entry port "knockout" closure panel.
Other modifications o panel 50 based on the description and
26 illustrations herein will likewise be apparent.
27 Re~erring now more particularly to Figures 17-19 of
,~. .; .
28 the accompanying drawings, there is illustrated another embodi-
.. 2g ment of the cable entry port means of the invention similar to
. , - ,: , .
. Figures 7-10. As here embodied, a pair of oppose~ converging
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1 tapered panel members, each designaLed 60, de~end fro~ the ins~.de
2 surface of end wall 3, substantially as described with reference
to Figures 7-10. A third closure panel 62 is attached to the
4 inside of end wall 3 adjacent ~he fron~ rim portion of aperture
22, and projects towards bottom wall 2 at an acute angle relative
6 to end wall 3. To accommodate the angular configuration of
7 third panel 62, the front facing edges of both panels 60 are
8 inclined toward bottom wall 2 at essentially the same angle as
g panel 62.
The inward edges 61 of each panel member 60 are
11 coupled by a frangible web 64 in any of the ways previously
12 described. Here, web 64 is attached along each of the edges 61
13 by a recessed web 65. The web also includes a central portion
~!
~; 14 of reduced thickness, indicated at 64a in Figure 19, as previously
discussed.
16 The innel~ost edge 63 of third panel 62 is also .
17 coupled to web 64 by another frangible web portion 65a, which is ¦
1~ recessed like web portions 65 to provide a sharp grasping edge.
:;
19 ' It will be understood that third paneI edge 63 could be fo~med
without attachment to web 64.
21 ~,~ As in the various embodiments previously described,
~;~ 22 the outwardly facing surfaces of panels 60, 62 may be for~ed
; I
23 with suitable secondary, or supplementary,grasping means. Thus, I
., ~
24 panels 60, 62 are sho~m with rib-like pro~ections 68, 69, ',
respectively, si~ilar to projections 35, and third panel 62 is
26 further formed with notches 69a or accommodating the mold
27 parts needed to form projections 68.
28 Referring now more particularly to Figures 20-22 of
9 the accompanying dra~Jings, there is illustrated a further
3, embodimen~ o ~he invention, wherein the cable en~ry port means
' ' ~ " ' ' '
',
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1 includes a group of four closure panel members, each adapted to
2 deflect laterally away from the aperture upon passage of a cable
~; 3 therethrough and to thereafter resistingly bear against the
4 installed cable. As here embodied, electrical ou~let box 1 is
~ - 5 advantageously formed with diag~nal wall portions 70 joining
;~ 6 bottom wall 2 with each of end walls 3 and 4 and the cable
; 7 entry apertures 72, substantially square in shape, are formed
8 in diagonal sections 70. Four closure panel members 74,
g separated by narrow openings 76, each converge angularly
. .
10 inwardly from a side rim of aperture 72 toward a common central , -
11 o~ening i8 which is smaller than the cross-sectional dimensions
12 of the electrical power cable. Advantageously, opening 78 is
13 substantially closed by a frangible web 80 joining an opposed
14 pair OL panel members 74. Also advantageously, frangible webs
82 connect web 80 to panel members 74 in any of the various
~;
16 ~2nners previously discussed.
17 Referring now more particularly to Figure 23, there
18 is illustrated a further embodiment of the invention, wherein
19 ' the pair of opposed tapered inwardly convçrging closure panel
20 ,i members illustrated in Figures 7-9 are joined to end wall 3
21 1 of outlet box 1 by means of a live, integrally molded-in hinge,
~2 , indicated generally by reference numeral 90. As is well known
23 by persons of ordinary skill in the molding art, plastic
24 materials may be molded with a constricted area, such as sho~m atl
90. in such a manner that the molecular structure becomes oriented,
26 50 zs to be flexible, while the surrounding material remains
27 relatively riid. The term "live hinge'l is commonly used in the -
28 art to refer to such an integral fleY~ible constriction in a molded
29 article.
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Figures 24-25 illustrate a further embodiment of
31 ~he invention including modified forms of the live hinge
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1 construction shown in Figure 23 and the rib-like supplementary
2 cable gripping projections shown in Figures 10 and 15. Thus, as
3 here embodied, a single inwardly angled closure panel member 100 .
is formed integrally with a projection or lug 101 extending
relatively inwardly of end wall 3 a distance approximately
6 equal to the point of attachment 103 of the free end portion 102
7 of panel 100 with the adjoining side wall 6 of outlet box 1.
8 End 102 o~ panel 100 is advantageously frangibly attached to
g side wall 6 in the manner previously described in connection
with Figures 15-16. As here embodied, panel 100 is also mounted ',
11 to lug 101 on end wall 3 by means of a live hinge construction,
12 indicated generally at 104.
Also, as here embodied9 the outwardly facing surface
14 f panel 100 is provided with a plurality of rib-like projections
lS lOj extending over the length thereof, each being similar to
16 projections 35, so as to provide a serrated surface for
17 resistingly bearing against installed cable 26 and for gripping
lg the cable upon reverse outward movement thereof. 7
19 '' It will be seen from the foregoLng that hingedly
mounting ciosure panel 100 relatively im~ardly of the cable entry
21 ~.' aperture 22 locates the rotation point about which panel 100
22 develops its ca~ming action closer to the point of gripping
23 enga ement with cable 26 to thereby provide maximum gripping
24 force of panel 100 against cable 26. Also, the provision of a
serrated surface on panel 100 serves to ensure gripping engage-
2~ ment o~ panel 100 with all sizes of electrical cable installed
27 in the cable entry aperture 22.
28 I?hile it will be understoo~ from the foregoing descrip-
29 tion that the outlet box of the present illvention is not limited
to the use of particular materials, the outlet box and the cable
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1 entry port structure are preferably formed integrally from a
2 molded thermoplastic resin material. In this regard, a certain
3 injection moldable thermoplastic resin material has been found
4 to produce highly satisfactory results and is given as an example
of the preferred mode of carrying out the invention, together
6 with other examples of suitable materials, from which still
7 further equivalent materials will be apparent to those of ordinary
8 skill in the art. Thus, it has been found that a thermoplastic
g resin blend of ABS (i.e., acrylonitrile-butadiene-styrene)
and P~O (i.e., polyphenylene oxide) sold by the General Electric
11 Company under the trade name "NORYL", Grades SE-100 or SE-l, is
12 a particularly preferred material from the standpoint of ease
13 of moldability, strength and high temperature resistance. More-
i
14 over, the "NORYL" material is sufficiently strong to meet the -
current standards of Underwritersl Laboratories, Inc. for
16 electFical outlet box cable clamping devices. It has also been
17 found that a vinyl resin material such as PVC (i.e., polyvinyl
18 chloride) sold by the Ethyl Corporation under the trade designa-
19 tion "Ethyl 7042" o~erates satisfactorily where only slight
20 Ij clamping action against the cable is desired or necessary, as in
21 ¦ the embodiment of the invention shown in Figures 11-14. However,
22 1 this material does not meet the aforementioned current
23 I Underwriters' Laboratoriesl standards for cable clamps in
24 ,, electrical outlet boxes. In addition to the foregoing, the
outlet box and cable entry port structure of the present inven-
26 tion may be formed integrally from a metallic material, for
27 example, by cast molding from aluminum or an aluminu~ alloy, I
28 or by die stamping the closure panel members from a ~etal having
2a suitable flexibility and resiLienc~, such as, e.g., spring steel
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the latter being thereafter bent inwardly to provide the cable
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entry port structure.
To the extent not already indicated, it also will
be understood by those of ordinary skill in the art that any
one of the various specific embodiments herein described and
illustrated may be further modified to incorporate features
shown in other of the specific embodiments, as desired. Thus,
for example, the provision of a serrated gripping surface on
panel 100 as shown in Figures 24-25 may be utilized on each
of the opposed pair of closure panels 14 shown in Figures 1-10.
Similarly, the hinged mounting shown in Figures 23-25 may be
utilized with the closure panels 44 shown in Figures 11-14.
- ~ The invention in its broader aspects t~erefore is
not limited to the specific embodiments herein shown and
described but departures may be made therefrom within the scope
of the accompanying claims, without departing from the
principles of the invention and without sacrificing its
chief advantages.
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