Improvements in Conduits for Electric Wires or Cables.
Year: 1899

page_text: Date of Application, 7th Feb., 1899-Accepted, 11th Mar., 1899
COMPLETE SPECIFICATION.
Improvements in Conduits for Electric Wires or Cables.
I, EDWARD HILL CALLAWAY, of No 44, Water Street, New York City, in the.
County and State of New York, United States of America, Mechanical Engineer, do
hereby declare the nature of thus invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
My improvement relates to conduits or subways adapted to receive and to hold
and protect electric wires or cables. The object of my invention is to provide a
conduit made in sections, the different parts of which can be easily and economically
manufactured, and readily put together, which will afford ample support and
protection to the wires, which will give a substantially perfect insulation at
comparatively small cost, which can be conveniently and quickly handled and
constructed, and which will nevertheless make the wires easily accessible for
renewals or repairs.
My invention consists first in the combination, in an electrical conduit, of
perforated sections of burnt clay, or other suitable material, such as asphalt, rubber
or glass, having countersunk recesses around the ends of the perforations, and
connecting sleeves made of glass or other suitable insulating material and equal
in number to the perforations, these sleeves being adapted to fit into the counter-
sunk recesses of adjacent sections and to thereby unite said sections and separate
or removable inner sections of tubes made of insulating material and adapted to
project into the connecting sleeves and to meet end to end, whereby the parts
can be easily made and readily fitted together, and a strong and durable conduit
formed which will afford a high degree of protection and insulation to the wires.
My invention also consists broadly in the combination with the perforated
conduit sections of inner sections of tubes made of insulating material and smaller
in diameter than the perforations and means for supporting the inner tubes in a
central position in the perforations whereby a film or wall of air is formed between
the inner tubes and the walls of the perforations, which serves to insulate the
inner tubes and at the same time to protect them from moisture.
My invention also consists in making the interior diameter of the connecting
sleeve less than the diameter of the perforation in the conduit section, as a result
of which the diameter of the inner tube is also less than the diameter of the
perforation and an air space is formed between the inner tube and the wall of the
perforation. In this case the inner sections of tubes are supported by the
connecting sleeves.
My invention also consists in plugging the ends of the inner tubes so as to
hermetically seal those tubes. In the most complete form of my invention I also
exhaust the inner tube of air before sealing it.
My invention also consists in certain other features of construction and com-
binations of parts hereinafter described and claimed
My invention is fully illustrated in the accompanying drawings, in which
Figure 1 shows two of the conduit sections connected together according to my
invention, and shown partly in section; Figure 2 is an end view of one of the

page_text: perforated sections; Figure 3 shows the adjoining ends of two of the inner tubes
partly in section and the method of joining them by the connecting sleeves;
Figure 4 is a perspective view of my preferred form of connecting sleeve; and
Figure 5 is a view of a second form of sleeve. Similar numbers denote simila
parts in the different figures.
'
Referring to the drawings, I represents the conduit section. In the best form of
my invention this section is made of burnt clay, or some other suitable non-
conducting material. It is provided with longitudinal perforations 2, 2, the number
of which can be varied according to the special requirements of each case. Around
the ends of the perforations are countersunk recesses 3, 3, adapted to receive
the ends of the connecting sleeves I prefer to bevel the wall of the recess at
its outer end, as shown 4 is a connecting sleeve which is made of glass or some
other suitable insulating material and which is adapted to fit into the countersunk
recesses 3, 3, of any two adjacent conduit sections, and to thereby unite the
sections and to make a continuous straight passage through the whole conduit
Two forms of sleeve are shown in the drawings. In the form illustrated in
Figure 4 the sleeve is provided with a triangular-shaped bead or projection 5
at its centre. When this kind of sleeve is employed the outer end or edge of the
countersunk recess 3 is beveled as already described so as to form a space or
cavity to receive the triangular-shaped bead of the sleeve, as clearly shown in
Figure 1. The space formed by the beveled edges is made a little larger than the
bead, so as to leave a space of say about one sixteenth of an inch between the
beveled surface and the surface of the bead, the purpose of this construction being
to provide a space to receive the cement with which the parts are fastened together
A second form of sleeve is shown in Figure 5. This is similar to the one already
described except that it has no central bead. When this variety of connecting
sleeve is used, the edges of the countersunk recess need not be beveled, although
if preferred the beveled edges can still be retained and the cavity formed thereby
can be completely filled with cement. I prefer to use the beaded sleeve in the
manner already described.
When my complete invention is employed I make the interior diameter of the
connecting sleeve somewhat less than the diameter of the perforation in the
conduit section, as shown in Figure 1, for the purpose of forming a film or wall of
air between the walls of the perforations and the inner tubes. 6,6 are inner
tubes constructed in sections. They are made of glass or some other suitable
insulating material and of such an exterior diameter as to project or fit into the
ends of the connecting sleeves. They are also made of such a length as to meet
at their ends so as to form a continuous or unbroken tube through which the
electric wires or cables can be passed and in which they can be held and
protected
When the connecting sleeve is made of a smaller interior diameter than the
perforation through the conduit section, the inner tube 6 is necessarily smaller
in its outer diameter than the perforation in the section. As a result of this the
interior tube is held in a central position out of contact with the inner surface
of the perforation, so that an air film or wall cushion is formed between this
inner tube and the conduit section. This provides an additional means of insula-
tion and also prevents moisture from reaching the inside of the tube. In the
form shown in the drawings the sections of inner tubing are made of the same
length as the conduit sections and are separate and removable portions of the
conduit.
7 is a suitable plug for hermetically sealing the end of the interior tube
The wire or cable passes through this plug. The plug can be made by wrapping
the end of the wire with fibrous material coated with asphaltum or by wrapping it
with rubber or other suitable non-conducting material and filling in cement around
this material. so as to form an air or liquid tight plug or the plug could be
provided on its outside with a screw thread and thus adapted to be screwed into a
thread formed on the inner surface of the tube 6, at its outer end.

page_text: The conduit is constructed from the parts already described in the following
manner. A section is first placed in position, then one of the inner tubes is
prepared for insertion in the conduit by coating it for about one and a half inches
on each end of the outer surface with liquid glass cement and by also coating
the end surface of the tube in the same manner. Any suitable kind of cement
can be used
In Figure 3 I have represented at S the manner and place of applica-
tion of this cement. This tube 6, thus-prepared, is then slipped into place through
the perforation in the conduit section, the coupling sleeve is next inserted in the
countersunk recess, being shipped over the end of the inner tube 6, the cement
previously applied to the inner tube firmly unites the end of the tube with the
connecting sleeve and forms thereby an air and liquid tight joint. The sections
of inner tubing, after being first properly coated with cement as already explained,
are then inserted into the second section of conduit and this second section is
applied to the first, the projecting ends of the connecting sleeves fitting into
countersunk recesses in the end of the second section and at the same time slipping
over the ends of the interior tubes in the second section. In this way the
ends of the two conduit sections are caused to meet around the connecting sleeves
and the ends of the interior tubes are also brought into contact, the interior_tubes
being firmly united by the cement previously applied to their end surfaces... Before
the second section is forced into place against the first section the recesses formed
at the end of these sections by the beveled edge are filled with hydraulic cement
in suitable quantity to fill the recess which is formed at this point when the two
sections are brought together When the two sections are pressed together the
hydraulic cement is thereby compressed and forms a tight, solid joint between the
two. The other sections of the conduit are laid in a similar manner. It will be
understood that each perforation is provided with interior tubes and connecting
sleeves in the manner already explained
In Figure 1 the first perforation at the left is represented as being without any
interior tubes or connecting sleeves, the purpose being to show the form of
perforation with its countersunk recesses and cavities formed by the beveled edges.
The second perforation from the left is represented as having been provided with
interior tubes and connecting sleeves. The same is true of the third perforation
from the left. In the last two cases the interior tubes and the sleeves are shown in
section
After the wiring has been inserted through the interior tubing the ends of this
tube are hermetically sealed, when my entire invention is used, by means of any
suitable plug, such as 7, through which the wire passed. In some cases I also
exhaust the interior tube of air after the wire has been passed through it and
before it is sealed.
My improved conduit is made up of parts which can be easily and economically
manufactured, and which can be handled and manipulated without any special
danger of breakage These parts are manufactured of such size and dimensions as
to be readily applied to one another, and they can be readily and quickly put
together The work of constructing a conduit from them can be. carried on
expeditiously and without the necessity of emploving skilled labor.
A very thorough insulation is provided for the wires or cables, so that it is
unnecessary to wrap these wires with any insulating material. The conduit
sections themselves are preferably made of insulating material, such as burnt clay.
The interior tubes are also made of insulating material, and in the best form of my
invention an air space or film is formed between these interior tubes and the conduit
section, which adds greatly to the completeness and perfection of the insulation.
Moreover if any moisture works its way through the material of the conduit
section, this air space operates to prevent the moisture from coming into contact
with the inner tube and working its way into the interior of that tube.
A very
strong and durable and effective joint is secured at the point of union of the
sections and inner tubes.
-
By exhausting the air and hermetically sealing the inner tubes, the introduction

page_text: of moisture into these tubes is prevented. If these tubes were open, currents of air
would pass through them, which would carry more or less moisture that would have
a harmful effect upon the wire or the cable. This is prevented by hermetically
sealing the tubes and exhausting them. In some cases it may not be necessary to
exhaust the tubes, as the hermetical sealing of the tubes alone may be found to be
sufficient for the prevention of such air currents. Even where the inner tube is
full of air, if the tube is sealed there is little chance of air currents being
produced.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
_
1. A conduit for electric wires or cables characterized by perforated sections of
suitable non-conducting material, having countersunk recesses around the end of
each perforation, a connecting sleeve made of insulating material adapted to fit
into the countersunk recesses of two adjacent sections and to thereby unite said
sections so that ends of said sections will come into contact with each other, and
removable inner sections of tubes made of insulating material and of such diameter
as to project into the connecting sleeve and of such length as to meet at their
ends, substantially as set forth
2. A conduit for electric wires or cables characterized by sections of baked clay
or similar insulating material provided with longitudinal perforations having
countersunk recesses around their ends, connecting sleeves of insulating material
extending into and fitting the countersunk recesses of adjacent sections and
thereby uniting said sections, inner sections of tubes of insulating material pro-
jecting into the connecting sleeves and having their ends cemented together,
and hermetical plugs at the ends of the inner tubing, substantially as set forth
3. A conduit for electric wires or cables characterized by sections made of
suitable material, and provided with longitudinal perforations, inner sections of
tubes of insulating material smaller in diameter than the perforations and means
for supporting the inner tubes in a central position in the perforations so as to
form a film or wall of air between the tubes and the walls of the perforations,
substantially as set forth.
4. A conduit for electric wires or cables characterized by sections of baked clay
or similar insulating material. provided with longitudinal perforations having
countersunk recesses around their ends, connecting sleeves of insulating material
extending into and fitting the countersunk recesses of adjacent sections and thereby
uniting said sections, inner sections of tubes of insulating material projecting
into the connecting sleeves and having their ends cemented together, and hermetical
plugs at the ends of the inner tubing, the inner tubing being exhausted of air,
substantially as set forth.
HASELTINE, LAKE & Co,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant