Improvements in Laying Electrical Conductors Underground.
Year: 1888

page_text: Date of Application, 14th Dec., 1888
Complete Specification Left, 1st July, 1889-Accepted, 3rd Aug., 1889
PROVISIONAL SPECIFICATION.
Improvements in Laying Electrical Conductors Underground.
We, GEORGE WILKINSON and LEONARD WILLIAM HOLMES Electrical Engineers
of 17 Coleman Street E.C. in the county of Middlesex do hereby declaro the nature
of this invention to be as follows:-
Our invention consists in an improved method of laying electrical conductors under-
ground and is especially applicable to heavy conductors used in suppling electricity
from a central station to a town or district for the purposes of obtaining light and
motive power. In all such systems it is necessary to have some form of conduit in
which the conductors can be laid. This conduit should be of cheap material and easy
to construct without special knowledge or experience on the part of the workmen, it
ought also to be watertight as nearly as possible and provided with suitable means for
draining off any water that may get in, any slight degree of moisture being removable
by forcing or drawing dry air or gas through the system of conduits.
We attain these objects by using a conduit of any suitable material, preferably of
galvanised iron of any suitable section with the top open as in ordinary channel iron
or spouting the sides of which have formed on the upper edges small gutters or
channels the object of which is described hereafter.
The conduit is made in lengths which may be joined together by any of the well
known methods; ono way of jointing the lengths of conduit together if they be of
galvanised iron is as follows-butt the two ends of the conduit together and slip over
the outside a jointing sleeve, the whole may then be run up solid with molten metal
such as lead or solder, but we do not confine ourselves to any particular method of
joining the seperate lengths of conduit together. At intervals, on the internal sides of
the conduits slots are arranged in which are put bridge-shaped insulators made of any
suitable material preferably of porcelain or glass provided on the top side with notches
or slots in which the conductors lie and are clamped by bolts which are preferably
insulated from the conductors. The conductors may be mado of any section and of
any suitable metal, preferably of solid drawn coppor rod, but if the rod is of too small
a section to give it the necessary rigidity any known means may be used to prevent it
from sagging.
At the points where the conductors lie on the insulating bridges they should prefer-
ably be wrapped with some insulating material for a distance of some inches on either
side of the insulating bridge. Drain pipes, for taking off any water which may find
its way into the conduit, aro fixed where required and connected preferably with the
sewers; these drain pipes are constructed so that no air can pass either in or out of
the conduit through them unless there is a considerable difference of pressure between
the inside of the conduit and the atmosphere. One way of accomplishing this is to
make the drain pipes with a deep bend or water trap in them. The top of the conduit
is made watertight by means of covers with flanged edges which dip into the small
gutters before named running along the upper odges of the conduit, in which some
watertight material is afterwards run such as pitch, resin, wax, lead, cement or any
other suitable substance.
The conduit is then covered with a strong cover which may be of iron or any other
suitable material. Joint boxes and distribution boxes are inserted in suitable positions
along the line of conduit, but we do not confine ourselves to any particular pattern or
design of box. Where the conduit is made of metal it will form a metallic line which
may be used for the passage of the return currents of electricity, in this case it will

page_text: act partially also as an earth plate of enormous surface, thus allowing the return
current of electricity partly to flow into the earth and so to reduce to a large extent
the resistance of the wholo circuit or circuits.
Dated this 14th day of December 1888.
GEORGE WILKINSON.
LEONARD WILLIAM HOLMES.
COMPLETE SPECIFICATION.
Improvements in Laying Electrical Conductors Underground.
We, GEORGE WILKINSON, and LEONARD WILLIAM HOLMES, Electrical Engineers,
of 17 Coleman Street, in the city of London, 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 consists in an improved method of, and means for, laying electrical
conductors underground, and is especially applicable to heavy conductors such as
may be employed for the supply of electricity from a given central station or the
like to a town or district for obtaining electric light or motive power therefrom.
The objects sought to be attained by the adoption of our said invention are,
first, the construction of an efficient conduit for carrying electric conductors under-
ground, of cheap inaterial, second, that the manipulation of said conduit in laying
or repairing should be within the capability of unskilled labor, third, that said
conduit should be impervious to moisture, and also bo provided with means for
draining any liquid that may collect therein; and to increase the efficiency of said
conduit, we may cause dry air or gas to circulate throughout the system, by the
adoption of any suitable method of promoting and maintaining said circulation.
In order that our invention may be the better understood, we have apponded the
accompanying sheet of drawings, to which we shall refer throughout the following
description.
In carrying our invention into effect we employ a conduit of any suitable
material, and of any suitable cross section proferring, however, to make use of
iron, such for instance as ordinary channel iron or spouting, in convenient lengths
which may be jointed together as bereinafter described. At suitable intervals we
place insulators inside said conduit made of any non conducting material that may
serve to keep the insulation resistance of the electric circuit up to the desired
standard. We prefer to use glass, porcelain, or vitrified earthenware as shown
by I Figures 1 and 2, which are a cross section of a conduit, and a longitudinal
section of the same with a junction box, respectively.
Said insulators are provided with notches for holding and supporting the electrical
conductors a, b, c, a separate cover or saddle piece d serving to prevent the rise or
"lift" of the conductors. Said saddle piece is constructed in such a manner as
to fit upon the top of the insulator I, forming part thereof, and the whole is
shaped externally so as to fit within the iron case A A', thus affording perfect
support to the conductors, and also tending to strengthen the conduit against
external pressure, it also being impossible, that under any circumstances, said
conductors could touch the metallic cover of the conduit, and establish electrical
contact therewith. When it is desirable to arrange the conduit to facilitate the
drawing in, or withdrawal of the conductors without removing the cover, these
insulators I may be made in long lengths to fit said conduit internally, and may
or may not have a removeable cover d.
The conductors abc may be of any suitable section or material, but if these be
of a small sectional area, so that it is a difficult matter to prevent deflection or
"sagging" between the insulators, we may adopt any suitable method of procuring
the requisite tightness, either causing the strain thereof to be borne by the

page_text: insulators I, or otherwise as may be practicable. In cases where bare, or uncovered
conductors are used with the spaced insulators I shown by Figures 1, 2, 3 and 5,
we prefer to insulate these by wrapping with a suitable insulating material at the
point where said conductors pass through the insulator, and continuing said
wrapping for two or three inches on both sides thereof.
We find it necessary in practice to employ junction boxes, B figures 2 and 4,
which may be placed at intervals for purposes of repair, testing, or joining
branches or sections of a system of electrical conductors with the mains thereof,
and may be termed joint or distribution boxes. We prefer to construct these in
two parts, fitted together in the manner shewn by k Figures 2 and 4 or in any
other manner that may be suitable therefor. We may make use of a foot plate,
chequer plate, or the like i which may or may not be level with the path or road,
and may seal said box B by means of a second plate j, both plates being provided
with a ledge, rim, or fillet for the exclusion of dust or wet, as shewn by the
drawings. We place at intervals along the conduit, drain pipes which may or
may not be connected to a joint, or distribution box B as shewn, so that the
perfect drainage of said conduit is effected. We prefer to arrange an inner pipe e
dipping nearly to the bottom of the outer pipe, which is pointed or shod to
enable it to be driven into the soil without excavating. The water collected in
the conduit drains into the pipe e, and rising between it and the pipe f, to be
discharged into a drain or sewer at g, forms an effectual trap, or water seal
therebetween, preventing the rise of effluvia therefrom. In cases where we attach
said drain pipe to the joint or distribution box B, we prefer to incline the base
thereof as shewn by h Figure 2, to prevent the collection of water therein.
The drain pipes arranged in the manner above described do not admit of the
passage of air or gas from or into the conduit, unless the difference between the
external atmospheric pressure, and that prevaling in the interior of said conduit
be excessive, although any amount of fluid collected may freely pass.
The "run
of the conduit may be of stamped, pressed, or rolled iron or other
metal, usod either single or doublo, as shewn by the cross section, Figure 1. The
cap or cover A in this case is bolted to the lower portion A' which supports the
insulators I and conductors a b c, a strip of india rubber or other resilient material/
being interposed, and compressed by the bolts m, m³, to form an air tight joint. We
may join the several lengths composing the conduit together by means of a sleeve, or
other equivalent device.
We may form the lower portion or trough of the conduit A³, Figure 3, with a pro-
jecting flange, bent to form a longitudinal channel n upon each side, into which the
edge of the upper part, or cover A may dip, and may be sealed when the bolts and
nuts m are tightened, by means of a luting of wax, cement, lead, or any substance or
material that may when poured or placed therein form an effectual seal, impervious to
moisture. We do not confine ourselves to the employment of bolts and nuts m in
joining the two parts of the conduit together A and A¹ as shewn, but may, in lieu
thereof make use of clips, o, tightened upon the projecting Hanges by means of a key
or collar p which be of any desired shape. This alternative arrangement is shewn by
the cross section Figure 7. We also do not, for purposes of distribution or jointing
confine ourselves to the use of a box or boxes B Figure 2, but may form a T or other
shaped joint in the manner shewn by Figure 4. e may arrange a series of con-
ductors through the conduit in any style or method, the insulators I being suitably
notched or grooved to suit any special requirement; one of said methods being shewn
at Figure 3. In all cases we prefer to form an orifice g at the base of each insulator I,
so that any moisture collected in the conduit may freely flow toward one of the drain
pipes hereinbefore referred to.
We
The metallic conduit, according to our invention, when properly laid down, may be
included in the electrical circuit, forming as it were, an earth plate of great area and
perfect and continuous contact, so that the so-called return current of electricity may
be in connection with the earth by means of a large area of exposed conducting
surface, thereby reducing the total resistance of the circuit.

page_text: Although we have hitherto described a conduit made in two parts, A A', a trough
and cover respectively, preferably of rolled stamped or pressed metal, and have shown
the same by the several views upon the accompanying sheet of drawings, we wish it to
be understood that we do not confine ourselves to the employment of any special
shape, either of insulators or of the conduit, nor to any metal or material that may be
applicable in the construction thereof, but we especially denote the novel methods of,
and means for, jointing the two parts of said conduit, and also of draining the same,
whether we employ a current of dry air or gas for maintaining the insulation or not,
as herein specified.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what
we claim is
First. The employment of metallic conduits, with insulators, for the reception of
electrical conductors substantially as herein described, with reference to the accom-
panying sheet of drawings.
Second. In a system of undergound electrical conductors as referred to in the
preceding claim, the methods of and means for, running or laying said conductors,
and maintaining the insulation thereof. substantially as herein described.
Third. In electrical conduits as above referred to, the division thereof through-
out into two parts A A¹, said division running longitudinally throughout, and
including the joint or distribution boxos B substantially as herein described with
reference to the accompanying drawings.
Fourth. In a system of electrical conduits divided longitudinally as above referred
to, the methods of joining the two parts A A¹ by bolts or clamps, so as to
be impervious to moisture substantially as herein described and shewn by the
drawings.
Fifth. In a system of electrical conduits as referred to in the preceding claims
the employment of drain pipes with a water seal or trap, substantially as sot
forth.
Dated this 29th day of June 1889
FREDK. WALKER & HYDE,
4, Little Moorfields, London, E.C., Agents for the Applicants.