An Improved Coupling for Attaching Electric Wire Conduits to Junction Boxes.
Year: 1897

page_text: Date of Application, 22nd Apr., 1897-Accepted, 3rd July, 1897
COMPLETE SPECIFICATION.
An Improved Coupling for Attaching Electric Wire Conduits to
Junction Boxes.
I, GEORGE CROYDON MARKS, of 18 Southampton Buildings, London, W.C. in the
County of Middlesex, Consulting Engineer (A communication from abroad by
John Patrick Coghlin, of 61 Park Street, City and County of Worcester, Massachu...
setts, U.S. America, Electrical Engineer,) do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
The object of this invention is to provide an improved coupling for attaching
electric wire conduits to junction boxes, which shall be very simple, of low cost, and
which can be very easily and quickly applied.
To this end, the invention consists of the parts herein described and claimed,
and illustrated in the accompanying drawing, in which,
Fig. 1 is a sectional elevation illustrating how my improved coupling may be
used to secure a number of conduits to a junction box,
Fig. 2 is a bottom plan view of the parts shown in Fig. 1,
Fig. 3 is an enlarged sectional view of the preferred form of coupling, and
Figs. 4 and 5 are views similar to Fig. 3 illustrating modifications hereinafter
referred to at length.
The ordinary junction box for electric wire conduits consists of a box of any
desired shape projecting from which are hollow, screw-threaded nipples or arms,
to which the conduits or pipes may be attached.
This form of box is exceedingly difficult to place in position for the reasons,
first that the pipes can only be led to said box in the directions in which said
screw-threaded arms project, and therefore a special box is required for each
location; and, second, it is extremely difficult to put the box in lace, as the pipes
have to be sprung to one side, or the junction box set in position with the pipes,
and both these operations necessitate the placing of the junction box in position
at the same time with the pipes, which is very objectionable, as the pipes are
generally placed in a building before the same is finished, and the junction box,
if in position during the finishing operation, is very apt to be broken or defaced.
By this invention, a junction box is provided, which has plain sides, and for a
coupling a coupling-bushing is used, exteriorly threaded and preferably interiorly
insulated, which bushing preferably has a head, which is squared, or which has
spanner-holes, so that the bushing can be screwed into the conduit or coupling
thereon from the interior of the junction box.
By this arrangement, the pipes or conduits can be placed in a building, and a
block of wood left between them while the building is being finished, or the pipes
can be left projecting to the points that they will occupy on the junction box.
Then, thereafter, my junction box can be slipped in between the ends of the
conduits or pipes, the coupling bushings inserted in the interior of the junction
box and screwed out into the conduits or pipes, which can be done in a very short
time as compared with the ordinary practice.

page_text: This new way of attaching the conduits is very advantageous as the junction
boxes can be placed in position or taken out at any time.
Referring to the drawing and in detail, 4 designates a junction box which may
be circular, square, or of any desired shape.
The same is made with plain sides, and has its interior insulated, as indicated in
heavy lines.
B,B,B,B indicate the conduits or pipes for the eletric wires, which may be of
the ordinary pattern, consisting of light, wrought-iron pipes interiorly insulated
These pipes are brought up to the position they will finally occupy.
the junction box is slipped in between the ends of the pipes."
Thereafter
C designates the improved coupling bushing. The same is exteriorly screw-
threaded, as shown at 10, and interiorly insulated, as at 11, which insulation may
consist either of a coating of porcelain or other insulating compound, or of a thin
bushing of fiber inserted into the main bushing.
The said bushing also has a head 13, which may be made in the form of a nut
as indicated at 14 in Fig. 2, or which may have spanner-holes, as indicated at 15
in Fig. 1.
Couplings 16 are preferably placed on the ends of the pipes or conduits when
thev are placed in position.
Small washers as 17 are preferably placed between the ends of the couplings 16
and the junction box, and also preferably fitted on to the coupling bushings to
bear on the under side of the head are washers or gaskets 18.
To couple the conduit tightly to the junction box, all that is necessary is to put
the bushing into the inside of the junction box, and push it outwardly through a
hole, which can be bored or formed in the side of the junction box wherever a pipe
or conduit is to join the junction box.
The bushing is then turned so that the same will screw into the coupling 16,
and this will draw the coupling up tightly against the side of the box, and will
rigidly secure the conduit to the box.
The coupling 16, engaging the outer side of the box, and the head 13 of the
coupling bushing the inside of the box, the pipe or conduit will be securely
attached to the box.
The coupling is given a rounded corner, as at 19, so that the wires can be readily
drawn through the same.
By this connection, the conduits can be very quickly and easily attached to the
junction box.
The junction boxes can be made in large quantities, and holes drilled or punched
through the sides or bottom of the same in whatever direction it is desired to join
a conduit thereto.
Sometimes it is desired to use different sized pipes, for example, in Fig. 2, the
pipe B is represented as smaller than the pipes B,B.
One simple arrangement to accomplish this end is to make all the holes in the
junction box of the same size, and to use a small bushing-ring 20 on the outside of
the coupling bushing.
up
In Fig. 4 is shown a modification in which, instead of using a coupling on the
end of the conduit, the coupling bushing is screwed on the end of the pipe B
to a shoulder 22, and a nut 21 is screwed on the outside of the coupling-bushing.
In Fig. 5, substantially the same construction is represented, except that instead
of using a head on the coupling-bushing, a nut 23 is screwed thereon.
It has been found in practice that by the use of my invention, the junction box
can be very quickly coupled in place at any desired time.
In some cases, the insulation may be omitted from the inside of the coupling
bushing, as it may be the practice in some cases to provide the wire with an extra
insulation instead of having insulation on the interior of the pipes, couplings and
junction boxes. If this practice is followed, the coupling bushings being located
on the inside, will permit the wires to be readily drawn therethrough without
abrasion to their insulation.

page_text: The details herein described may be greatly varied by a skilled mechanic without
departing from the scope of my invention, as expressed in the claims.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I claim
is:-
1. The combination in a junction box for electric conduits, of a coupling for
attaching the conduit thereto, consisting of a hollow coupling bushing exteriorly
screw-threaded, and interiorly smooth, substantially as described.
2. The combination with a junction box for electric conduits, of a coupling for
attaching the conduit thereto, consisting of a coupling bushing exteriorly screw-
threaded and interiorly insulated, substantially as described.
3. The combination with a junction box for electric conduits, of a coupling for
attaching the conduit thereto, consisting of a coupling bushing exteriorly threaded
and interiorly insulated, and having a head so that the bushing can be screwed
to the conduit from the inside of the box, substantially as described.
4. The combination with a junction box for electric conduits, a conduit or pipe
having a coupling as 16 on the end thereof, a coupling bushing exteriorly screw-
threaded and interiorly insulated, having a head and adapted to be screwed into
said coupling 16 from the interior of the box, so that the coupling 16 will be drawn
tightly against the outside of the box, and the head of the bushing will engage the
inside of the box, and thereby tightly connect the conduit to the junction box,
substantially as described.
5. As an article of manufacture, a coupling bushing for attaching electric con-
duits to junction boxes, comprising a headed hollow bushing having a smooth or
insulated interior, substantially as described.
6. As an article of manufacture, a coupling bushing for attaching electric
conduits to junction boxes, comprising a bushing exteriorly screw-threaded and
interiorly insulated, substantially as described.
7. As an article of manufacture, a coupling for attaching an electric conduit to
a junction box, consisting of a coupling bushing exteriorly screw-threaded, and
interiorly insulated, and having a head so that the bushing can be screwed to the
conduit from the inside of the box, substantially as described.
P
1 1007
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and 18, Temple Street, Birmingham,
Agents.