Improvements in Conduits for Electrical Conductors.
Year: 1898

page_text: Date of Application, 20th July, 1898
Complete Specification Left, 25th Mar., 1899-Accepted, 27th May, 1899
Complete Specification Left, 25th Mar., 1899-Accepted, 27th May, 1899
Improvements in Conduits for Electrical Conductors.
FRANCIS DRAKE ĶENNEY, 58/9, London Wall, E.C., Engineer, and WALTER
VICTOR MORTEN, 58/9, London Wall, E.C., Engineer, do hereby declare the nature
of this invention to be as follows:-
Our invention consists of (1) novel forms of air-tight conduits to be laid in
subways, tunnels culverts, or other convenient situations, either under or above
ground. They may also be erected in vertical positions where suitable supports
can be provided.
(2) Also varions improvements in connection with the present well known
methods of constructing, laying, drying, jointing, connecting, distributing,
reducing the electrostatic capacity of keeping up the insulation resistance of, and
otherwise efficiently maintaining and when necessary removing all kinds of
electrical conductors. The conduits may be constructed of either iron, cement,
concrete, earthenware, glass, or other suitable material, or a combination of suitable
materials. They may be used for the purpose, amongst others, of providing as
perfect an air-tight protector as it is practically possible to construct for all
classes and kinds of electrical conductors.
The objects we have in view are (1) to provide without disturbing the public
thoroughfare, except at entrance holes, improved and more economical methods
than now exist for constructing, laying, distributing, working, maintaining, and
removing, when necessary, the great number of electrical conductors of all kinds
which are required by the inhabitants of large towns at the present time, and (2) to
provide more suitable material than lead or a composition of lead and tin for the
outside covering of electrical conductors of all kinds, but more especially for what
are known as dry core cables. (3) Also to obviate the use of a separate tube or
duct for each and every cable or conductor.
The conduits in this invention shall for preference be constructed of good cast
iron. Their shape and dimensions will vary according to the positions and sizes
required, and the number and dimensions of the conductors, which may have to be
laid in them. The length of each section of the conduit shall, for preference, he twelve
feet and the well known socket and spigot ends of the ordinary gas or water mains
shall be adopted. The jointing together of the different sections of the conduit
can be performed by adopting any of the well known methods now practiced in
jointing gas mains. Each conduit shall be provided at convenient intervals
throughout its length with air-tight covers, lids, doors, manholes, or other suitable
devices for the purpose of allowing easy means of access at all times to the interior
of the conduits as may be required for laying, drying, testing, jointing, connecting
distributing, maintaining, inspecting, and when necessary removing the electrical

page_text: conductors contained therein. The said covers, lids, doors, manholes, or appur-
tenances shall, for preference, be constructed of cast iron.
Gun metal nozzles of well known designs may be fixed in the sides or ends of
the conduits for the purpose of allowing the wires or other contents to be taken
out for distribution or otherwise. The sizes of the nozzles will vary according
to requirements. When not in use the holes provided in the conduits for the
nozzles will be covered by air-tight gun-metal caps of well known design. The
usual cable head terminals or tabs may also be placed in the sides of the conduits
for the purpose of leading out small numbers of conductors for distribution along
the routes.
The conduits may be filled with dry air under pressure such pressure can be
maintained constant at about five pounds to the square inch. Suitable pressure
guages may be provided and fixed in the conduits at the most convenient points
for observation. The object of maintaining this constant pressure is not only to
indicate by means of the pressure guages when a leakage occurs, but also to pre-
Tent the entrance of moisture into the conduit, and on a guage indicating a leak
the pressure may be increased, and so prevent any dampness entering the conduit.
Calcium chloride, or other deliquescent substance, in suitable receptacles may
be placed at necessary intervals inside the conduits. Wire connections may be
made between the receptacles mentioned and the outside of the conduits or with
spare wires in the conduit, in order to provide the means of making electrical
tests. The result of such tests shall indicate the hygrostatic conditions of the
interior of the conduits and localise the section in which any fault may exist.
Strips of canvas or other suitable material of convenient dimensions may be used
to prevent damage by friction during the process of drawing the cables or other
conductors into or out of the conduits.
In terminating a conduit at, for example, a telephone exchange, where it may be
desirable to run the wires from the underground system to the top floor of a build-
ing, the proposed conduits can be carried up by placing them together section
after section vertically taking the necessary support by fixings from the walls
of the building, or by other means. Bends of any angle can be made in any
section of the conduits, and the cables can be drawn through such bends without
any damage to the wires or covering of the cables. At the test room end of the
conduits the last section of each may be slightly enlarged and altered in shape in
order to allow terminals or tabs being fixed in the conduits for each wire contained
therein. This part of the invention will be the means of reducing the space
occupied to one fifth of that required at present when cable heads are used. It
telephone cables are laid in the proposed conduits they can be made to contain
as many as 1000 wires each, as the lead covering is unnecessary. The present lead
covered cables usually contain about 400 wires. Our conduits of large size will
preferably contain about 14,000 wires; but a conduit can be provided to take a
much larger number: Should 1000 conductors under this invention be laid, length
for length, they will be of much less weight than the present 400 wire cables.
Therefore, much longer lengths can be conveniently handled, reducing the number
of wire joints in a mile, of say, 12,000 conductors, from a 144,000 as at present,
to 96,000 under the proposed system, and plumbers work will be entirely obviated.
As the electrostatic capacity of conductors laid in the proposed conduits will be
much lower than in cables laid under the existing circumstances, and as the
insulation resistance is more effectively maintained, the working of the circuits
will be greatly improved.
6
The distribution of the wire from the conduits along the route of the same
can be performed with ease and at any time. Great facilities will be provided
for T-jointing at intervals of about 200 yards. Only the actual number of wires
required from time to time for connection to the branches need be T-jointed.
Whereas in the lead covered cables now in use the whole of the wires required for 5
branching must be connected permanently at different points, and if T-jointed

page_text: permanently, as has been proposed, then the electrostatic capacity must be increased
to such an extent as to lower the efficiency.
In the event of the use of particular circuits being discontinued, the wires made
spare in a branch can be immediately disconnected from the cable, thereby leaving
such wires free again for use at some other point along the route. Other advan-
tages are quite obvious in connection with this improved method of dealing with
the connection and dis-connection of spare brunch wires in the system.
All wires laid in the proposed conduits may be perfectly accessible at all times,
through the doors or covers, herein mentioned, and the number of cables or wires
can be increased or decreased according to requirements without injury to any of
the cables or wires already contained in the conduit.
The number of spare wires can be reduced under this system to about one half
of the number necessary under the existing systems as additional wires may be
laid as required.
We, FRANCIS DRAKE KENNEY and WALTER VICTOR MORTEN, of 58 and 59,
London Wall, London, E.C., Electrical Engineers, 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;—
Our invention relates to conduits for electrical conductors placed in subways
or other situations where covers can be removed to give access to the conductors
within for testing or connecting.
The accompanying drawings shew the construction of conduits according to our
invention, and how several of these may be accommodated in a subway.
Fig. 1 is a section of the subway.
Fig. 2 is a part elevation and Fig. 3 is a part plan of a length of conduit, Fig. 4
is a section at A and Fig. 5 is a section at 13.
We make the conduits in lengths of iron pipe a of flat section, these lengths
being jointed together air-tight in the usual way. At convenient intervals we
make part of the pipe at thicker with a lateral opening provided with a cover e
secured by bolts and nuts with suitable packing to render the joint air-tight. In
the conduit we place a number of cables 7 above one another, each cable consisting
of a number of wires insulated by paper packed together and wrapped with suitable
covering of paper secured by thread. By removing any of the covers & access can
be got to any of the cables, and, owing to the greater thickness of the conduit at
the place where the opening is, wires from the lower cables can be led across the
others to the upper side of the conduit where they can be passed through insulating
plugs screwed into the iron of the pipe. In order to expel moisture and prevent
access of moisture to the conduit, we pump into it from time to time, air, so as to
keep its interior charged with air at a pressure a little above that of the atmosphere.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed. we declare that what
we claim is;-
-
A conduit for electrical conductors consisting of lengths of pipe of flat section

page_text: jointed tightly together and provided at suitable intervals with lateral openings
with air tight covers, the conduit being charged with air a little above atmospheric
pressure, substantially as and for the purpose set forth.
Dated this 25th day of March 1899.
ABEL & IMRAY,
Agents for the Applicants.