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Патент USA US2411017

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NOV. 12, 1946.
G_ B, BENANDER
2,411,017
OUTLET BOX AND GROUND STRAP PROVIDED WITH CABLE CLAMPS
Original Filed April 11, 1942
Inventor‘:
GGQiQ B. ehander;
H635 Attornetg.
Patented Nov. 12, 1946 _
' 2,411,017
UNITED \ ‘STATE s; PATENT ‘OFFICE f I
' 2,411,017
OUTLET BOX AND GROUND STRAP BRO
VIDED WITH CABLE CLAMPS
.
George B. Benandelgloakla‘wn, R.‘ I., assignor to
Monowatt Electrical Corporation, a. corporation
of Connecticut ,
Original application April 11, 1942, Serial No.
438,545. Divided and this application April 19,
1944, Serial No. 531,797
5 Claims.
1
This application is a division of my applica
tion Serial No. 438,545, ?led April 11, 1942, issued
as Patent No. 2,362,794, November 14, 1944.
The present invention relates to wiring devices
of the type in which the device is part of the box
for enclosing the connections to the power con
ductors. Such a wiring device is particularly
adapted to surface wiring systems and may be
.
(Cl. 174-51) '
.
,
2.
conductors. ‘Ifhe openings are formed partly in
the base and partly in the cover and are blocked
by knockouts 6, 7, and 8 of different‘sizes, one
or more of which are removed depending upon
the size and type of power conductor to be ‘con
nected to the device. Along the sides of the cover
and base at each end are knockouts 8 for use in
open wiring. The covers are attached to the re
termed a combined outlet and outlet box.‘
spective bases by screws in threaded into sockets
It is desirable .that the devices be capable of 10 II in the base, and when assembled the base
use in wiring systems using metallic armored
and cover serve as an outlet box for enclosingthe
cable, non-metallic cable (cable having a non
metallic sheath 0r armor) and knob and'tube
open wiring. In the metallic armored cable
device and its connections with the power con
ductors clamped between the cover and base. .
When the wiring devices are used with metallic
system, a continuous ground connection must be 15 armored cable, the ground connection to the
carried through the metallic armor. In the pres
armor is made through a ground strap l2 having
ent invention this is done by means of a ground.
screw holes l3 inline with the screw holes 3 in
strap used interchangeably with each of the de-_
the base so-that the ground strap and base are
vices and having clampsfor holding the cable
secured to the support by the same screws. The
and making the ground connection to the metal~ 20 base is seated on the ground strap with its ends
lic armor.' In systems using non-metallic cable
con?ned between upwardly extending ?anges H
or open wiring, the ground strap is not necessary
.at the ends of the ground. strap. At the top the
and its expense is eliminated.‘
The object of my invention is- to provide an
?anges M are bent outwardly to provide horizon
tal ?anges I-5 which are suitably indented at
improved construction and arrangement in wir 25 IE to provide the lower half of a clamp for grip,
ing devices of this type, particularly an improved
ping metallic armored cable. The upper half of
grounding strap and for a consideration of what ' the clamp is provided by a clamping member I‘!
I'believe to be novel and my invention, attention
having tongues 88 slidable in slots IS in the
is directed to the following description and the
?anges l5 and having tongues 20 extending along
claims appended thereto.
30 the inner faces of the ?anges M. The'upper
In the accompanying drawing, Fig. 1 is a top
clamping member I‘! at its top is provided with a
plan view of part of a surface wiring system
tapered recess 2| of the same shape as the ta
using metallic‘ armored power conductors and
pered projection 22 at the ends of the base and
wiring devices embodying my invention; Fig. 2 is
, cover so the device may be assembled on the
a view similar to Fig. 1 with the covers of the 35 ground strap without disassembling the clamp.
wiring devices removed; Fig. 3 is an exploded
' perspective view or the switch appearing in Fig.
1; and Fig. 4 is an exploded perspective view of
The tongues 20 which project inwardly beyond
the extreme ends of the base and cover serve to
locate the device on the ground strap. The
clamping members are held together by screws
Referring to the drawing, each of the wiring 40 23 extending loosely through the center of the
devices has an elongated base I and a cover 2
upper clamping member I‘! and threaded into the
both of which may be made of suitable molded ‘
center of the ?ange I5. The upper clamping
insulating material. The baseis provided with
member is indented at 24 and is provided with
screw holes 3 for attachment to a supporting
a ?ange 24a for more effectively gripping metal
surface and is narrow enough so that it can be 45 lic cable. As shown more clearly in Fig. 2, the
attached to the narrow edge of two-by-four
openings through the clamps are in line with the _
framingv when used in an open wiring system.
openings in the device.
‘
Along the sides of the base members are projec~
In the single pole switch, as shown most clearly
tions 4 which are of different sizes and which ?t
‘in Fig. 3, the base is provided with a hollow
in corresponding depressions 5 in the sidescf 60 projection 25 housing the switch mechanism
the respective covers. The projections and de
which need not be illustrated for the purposes of
pressions 4 and 5 insure that the covers are as
the present invention. Across the open top of the
semblecl with and properly positioned on the
hollow projection 25 are a strip of insulating ma
bases for which’ they are designed. At each end
terial 26 and a metal strap 21 ?xed by screws 28
the lamp socket appearing in Fig. 1.
. of the device are two openings for armored power 55 to the ends of the projection 25.
The strap 27
2,411,017
g
is provided with a slot v28' through which the
switch handle 28 of molded insulating material
projects and is provided with arcuate seats St
on each side of the slot 28' pivotally engaged
.
the device and its enclosing box comprise a co -
plete unit with the openings and clamps for power
conductors.‘ The terminals for the device are
located on opposite sides of the enclosing box,
- by projections 88 integral with the switch han
die. ‘The switch handle accordingly is pivoted
on the strap 2?. At opposite ends the strap 2?
is provided with terminal screws 82 so that the
strap, which is insulated from‘ the switch, may
be used as a bus bar. At one side of the base is 10
and at the center is a bus bar insulated from the
device which, as described above, may be used .to
feed a circuit through the device without the use
of jumpers or other connections. The wiringis
accordingly simpli?ed since all of the wiring con
nections are made to terminal screws.
. ?xed a conductive strip or bus bards having ter
The use of the devices is further simpli?ed by
minal screws 35 at opposite ends and at one end
‘the conductor clamping arrangement having
. having an integral arm 35 (Fig. 2) connected to
knockouts 8, l, and 8 for use with #12 and #1t
two and three conductor metallic and non
25. The other switch contact is connected to a 15 ,metallic armored cable and knockouts @- for use
strip 85 carrying a terminal screw 37 which is on p with #12 and #14 open wiring. The knockouts
the opposite side of the base; from the terminals ‘
8, ‘i, and 8 are spaced apart along conductor re
3t. ' The switch terminals 85 and 31 are accord
ceiving grooves St at each-end of the base i and
ingly on opposite sides of the base, and the
cover 2. The knockouts 8 are at the outer ends
mounting strap or bus bar 21 which is insulated 20 of the grooves and have surfaces 85 for gripping
from the switch terminals and is used to elimi
two conductor non-metallic "cable in sizes #12
nate the need for a jumper extends lengthwisev
and, #14. The knockouts ‘I are arranged in
of the base at the center. The switch handle
channels 88 transvetl se to the length of the grooves
one of the switch contacts inside the projection
29 projects out through a slot 88 in the cover.
85 and have surfs ees 81 projecting above the \
When the switch is used to control a device at 25 grooves st'pfor gripping three conductor non~
the end of a power ‘line, as shown in Figs. 1 and 2,
metallic and metallic armored cable in size #14
the ground conductors 39 and 48 are connected
and two conductor metallic armored cable in sizes
by the terminal screws 82 to opposite'ends of the
#12 and #14. The knockouts ‘i may be removed
strap 27; The incoming live conductor 4! is con
by a screw driver or similar prying tool inserted
_ nected to the terminal screw 34 at one end of 30 into the space between the knockout and the
the switch, and the outgoing live conductor s2
sides of the channel 88. The knockouts 8 have
is connected to the terminal screw 3i at the oppo
thin removable sections 88 at the inner edges of
site end. The circuit between the terminal screws
ribs 89. The sections 88 form closures for the
34 and 81 is respectively made and broken in the’
von and oil‘ positions of the switch.
'
-
_ grooves 84 and when removed provide su?icient
35 space for leading the conductors into the device
In the lamp socket, as shown more clearly in
as illustrated in Fig. 2. The grooves 84 are shaped
Fig. 4, the base I is provided at the center with
to properly grip ‘the largest cable (three con
a cylindrical projection 43 on the upper-end of
ductor #12 non-metallic and metallic. armored
which is mounted a screw shell 44, and the cover 2
cable) for which the devices arev designed. By_
is provided with a cylindrical projection 45 sur 40 removing one or more of the knockouts 6, ‘I, and 8,
rounding the upper end of the screw shell- The
the device may be used with the customary sizes
screw shell is ?xed on the upper end of the projec
of armored cable. No adjustment of the con
tion 43 by screws 48 threaded into the projection
ductor clamp is' required other than the selective
through a ?ange 41‘ at the bottom of the screw .
removal of the proper knockouts.
shell. Integral with the screw shell ‘is a metal 45
strip 48 connected to a terminal strip 49 by means
Because-oi’ the correlation of the wiring devices
and the ground strap,‘ the expense of wiring is
of a screw 58 threaded through the strips 48 and '
‘decreased since the same wiring devices are inter
.49 intothe base. The strip 48 at'opposite ends
is provided with terminal screws-5|. Within the
'
'
changeably usable with non-metallic and metallic
armored cable and the groundstrap need be sup
screw shell is a center contact-52 ?xed to the 50 plied only ior metallic armored cable. '
_
_ upper. end'of the projection 43 by a rivet 53 which
What I claim as new and desire to secure by
connects ,the center contact to one end of strip
' Letters Patent of the United‘ States is: -
54 on the under side of the projection 43. The
1. A metallic ground strap ior'use with a wir
other end of the strip 54 is connected by a rivet
ing ‘device, said device comprising a housing of
55 to a terminal strip 56 provided at opposite 55 insulating .material enclosing connector‘ mem
ends with terminal screws 51. The socket
bers, said housing comprising a base’ having a
terminal screws 5| and 51, like the switch terminal
?at bottom adapted to rest on a supporting sur
screws 34 and 31, areat opposite sides of the‘ base.
‘ lace and a cover,- and having cable admission
At the center of the base is a terminal strip or bus.
openings and associated clamps for non-‘metallic
bar 58, provided at opposite ends with terminal 60 armored cable, said ground strap comprising a
screws 59 and extending up over the top of the
?at strip of metal having upturned ?anges inte
projection 43 through a ‘groove 80. The bus bar
grally formed therewith at the ‘ends ‘of, said strip,
58 extends beneath the screw shell 44 and center
said ?anges being spaced to receive between
contact 52 and is insulated therefrom‘by a strip
them said housing, said ?anges having inwardly
of insulating material 6| in the groove 60 on top 65 curved top surfaces on which the metallic armor
of the bus bar 58. The bus bar 58 eliminates the
of a metallic armored cable may lie, top clamp
need for jumpers in the same manner as the bus
members having downwardly facing surfaces
complementary to said ?rst named surfaces, and
struction. In the wiring system shown in Figs. 7
screws for positioning the top clamp members
' 1 and 2, the ground conductor‘ 40 is connected to 70 with respect to said ?anges, the spaces ‘between
one of the terminal screws 5|, and the live con
said ?anges and clamp members being so posi
ductor 42 in series with the switch terminals 34
tioned that they are adapted to stand in line
bar TL in the previously described switch con
and 81 is connected to one of the terminal screws
51.
’
In each of the above described wiring devices‘ 75
‘with the cable admission openings of said wirin,g
e
ce.
/
'
2. In a surface wiring device, a ?at ground
v 2,411,017
strap for attachment to a supporting surface, '
?anges on said strap, a combined outlet and out
let box of insulating material between said
?anges, clamps for metallic armored cable co
operating with said ?anges, said clamps having
portions against which the end walls of the box
iii; to locate'the box_ between the ?anges, and
' cable admission openings in the box in line with
said clamps‘.
,
V a
3. A metallic ground strap for use with a wir
ing device, said device comprising a housing of
insulating material enclosing connector mem-
bers, said housing comprising a base having a
, ?at bottom adapted to rest on a supporting sur
face and a cover, and having cable admission
openings, said ground strap comprising a ?at
4. The combination with a wiring device com
prising a casing of insulating material having
cable receiving openings in its end ‘walls and a
?at bottom wall, of a metallic ground strap com
prising a ?at plate having at its two- ends ad
justable cable clamps which position between
them said casing with the clamps in line with
said cable receiving openings, said ?at plate ?t
ting against the ?at bottom wall of the casing
10 whereby when the wiring device is mounted on
a wall the ?at plate lies between the ‘bottom of
the casing and such wall,
'
5. The combination with a wiring device com
prising a casing of insulating material having
cable receiving openings in its end walls and a
?at bottom wall, of a metallic ground strap com
prising a ?at plate having at its two ends ad
strip of metal having upwardly projecting
justable cable clamps which position between
?anges at its ends, said ?anges being spaced to
them said casing with the clamps in line with
receive between them said housing, said ?anges
having upwardly facing top surfaces on which 20 said cable receiving openings, said-?at plate ?t
ting against the ?at bottom wall of the casing
wherebywhen the wiring device, is mounted on
a wall the ?at plate lies between the bottom of
the casing and such wall, and means providing
to said ?rst named surfaces, and means for po
sitioning the top clamping members with re 25 interengaging parts between the endwalls of
the casing and the cable clamps to hold the cas
spect to said ?anges, the spaces between said
ing on the ground strap.
?anges and clamping members being so posi
tioned that they are adapted, to stand in line
GEORGE B. BENAl't'DER. ‘
with the cable admission openings of said wiring
the metallic armor of a metallic armored cable
may lie, top clamping members having down
wardly facing clamping surfaces complementary
device.
'
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