Improvements in Jointing and Connecting Electric Cables.
Year: 1894

page_text: Date of Application, 12th Jan., 1894
Complete Specification Left, 12th Oct., 1894-Arcepted, 5th Jan., 1895
PROVISIONAL SPECIFICATION.
Improvements in Jointing and Connecting Electric Cables.
GEORGE HINDE NISBETT, 248, Stanstead Road Forest Hill in the County of
Kent, Electrical Engineer, do hereby declare the nature of this invention to be as
follows:-
--
My invention relates to improvements in jointing conductors and the making
provision for distributing the current therefrom in the following method, the
principle being equally applicable to any form of conductor, but supposing I am
dealing with a concentric cable having two or more sets of conductors I prepare
the ends for jointing in the following manner :-The inner conductors of the two
ends of cable that require to be jointed together are stripped for a distance of half
an inch. I then strip back the outer conductors leaving three-quarters of an inch
of the inner insulations exposed to the air. Then I strip back the outer
insulations on each side to the distance of " and then if the cable be sheathed
with lead or armour I strip back this for a distance of say 1".
Both ends of the cable being prepared in this manner they are introduced
through suitable holes or slots into a cast iron or other containing box. Instead of
connecting these cables together by means of clamps such as are at present in use
or those of any other type I now insert a mould or moulds so formed that I can
cast metal so as to connect the two inner conductors solidly together in one mass.
Then by pouring the metal into a second partition in the mould or moulds I can
connect the outer conductor together by a strip or strips of metal and if there be
more conductors I have separate chambers so formed that I can pour in metal and
connect as many pairs as there may be.
In order to preserve the insulation between the each pair of cables I protect each
piece of insulation which has been previously bared, either by winding on tape
until a disc has been formed, or else I so form my mould that there are additional
chambers in which I can cast or place discs of plaster of paris or other suitable
material so as to make it impossible for the metal when casting in one set of
connections to run in and make contact with the metal used for making another set
of connections.
Having prepared my mould I take tinmans solder or other suitable alloy and
am careful to see that the temperature is high enough to raise the whole of the
surfaces which I wish to connect together for carrying the electric current to such
a temperature that they will become tinned by the alloy so that it makes good
electrical connection.
When currents of large quantity are being dealt with in order to prevent any
heating in junctions so made and to reduce the quantity of alloy necessary to carry
the current I spray out each separate wire or strip forming the conductor in order
that the metal when cast may come intimately into contact with every portion of
the surface of same, and I proportion the surface of the copper in contact with the
metal so burnt in in proportion to the current to be carried.
It is also desirable when working with currents of large quantity to insert metal
strips in the mould and to burn these into connection with the cables by means of
the alloy used. These strips will be so arranged that the current will only be
conducted through the alloy itself over a very short distance and in this way the
resistance of the joint will be very low...

page_text: When it is desired to construct a T joint consisting of two or more cables a
similar method is followed the moulds being specially shaped for each case and
size of wire to be dealt with.
Should it be desired to have changeable connections or fuses in the boxes the
necessary terminals are cast into the alloy the terminals being placed in position in
the mould and so fixed at the same time as the joint between one or more cables
is made.
In place of using a removable metal mould which when removed leaves a clear
air space round each set of connections, in some cases I use a mould constructed
of suitable insulating material which is left permanently in position after the alloy
has been cast in which makes the necessary connections.
Dated this 19th day of January 1804
$
12
Improvements in Jointing and Connecting Electric Cables.
I, GEORGE HINDE NISBETT of 248 Stanstead Road Forest Hill in the County
of. Kent, 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:-
While it is exceedingly easy to join cables having only a single conductor or
a number of conductors all carrying the same current in the same direction there
have been many very great pràctical difficulties in properly splicing-or jointing
cables having several concentric conductors each insulated from the other and
independent of the other, and in taking off branches or service connections
therefrom. These connections have hitherto been formed by splicing and soldering—
a very difficult and tedious work-or by copper or other metallic clamps and
connecting bars arranged in such a way that the various conductors may be
separated out sufficiently to allow a ready connection of other wires either at
the time or afterwards. These metallic clamps have hitherto been found to be
not only expensive but also unsatisfactory, as the connections, however carefully
made, are apt to become faulty after a lapse of time, and the clamps frequently
work loose, thus breaking the continuity of the conductor.
Now, my invention is designed to joint permanently and effectually all the
various conductors in the same cable or a number of cables without difficulty,
without interfering with each other, and so that each joint if requisite could be
repaired without any other joint being affected, the joints themselves being equally
conductive with the remainder of the cable.
The invention is best described by aid of the accompanying drawings, in
which,
Figure 1 shows the jointing of a triple concentric cable with copper terminals at
the joint. To these terminals may be joined fuses or other connections for
transmitting the current to similar terminals connected to a service or other
cable.
Figure 2 is a triple concentric three way junction or joint with no connections
taken off.
Figure 3 is a double concentric four way junction or joint.
Figure 4 is a section on line ab of Figure 1.
Figure 5 a section through z = of Figure 2.
Figure 6 is a plan of the mould for casting the joints shown in Figure 1.
Figure 7 section through Figure 8, and
Figure 8 an end elevation of the mould.

page_text: In these, A is the sheathing surrounding the cable (not always used);
B, B, B, insulator; C, end of annular conductor or ring of conductors splayed out;
D end of inner annular conductors (these are also preferably splayed out in
similar manner); E, E, ends of innermost conductor or bunch of conductors
which can be splayed out or not as desired; F, F, F' a mass of tin solder or other
like comparatively fusible and good conducting metal cast in position round the
two splayed ends of each pair of conductors uniting them. Great care must be
taken in casting this solder, that the temperature is high enough to raise the whole
of the surfaces which it is desired to connect for carrying the electric current to
such a temperature that they will become tinned by the alloy so that it will make
a good electrical connection. For this purpose also the ends of the conductors
should be very carefully cleaned, and a small quantity of some suitable flux placed
upon them before the alloy is cast. G is a strip or wire of copper laid in the
mould prior to casting and placed in very close contact at each end with the cable
conductor. This may be used with cables that have conductors of large cross
section and in those cases in which it is not convenient or desirable to make the
cast alloy so large in cross section as to equal in conductivity the conductor in the
cable itself. These strips are so arranged that the current will only be conducted
through the alloy itself for a very minute distance and in this way the resistance
of the joint will be very low. H, are copper strips, which, if strips G be used
are preferably united to these strips and act as terminals for branch service. Like
letters relate to like parts on all the drawings.
Referring now to the drawings of the mould, especially Figure 7, the
spaces CD E¹ are those left for the solder. G, is the copper strip already
mentioned. J, the strengthening piece and K the mould. L, are open spaces left
in the mould to insure that the solder shall not pass through from one compartment
to the next.
Having given this one illustration of a mould applicable to Figure 1, the method
of making moulds for fresh joints will be obvious without further illustration, but
I do not bind myself to this exact form of moulds, for in some instances, I may
make the mould itself of suitable insulating material which is left permanently in
position after the alloy has been cast in. In some instances too when using
metallic moulds, on removing the joint from the mould, I prefer to fill in the space
left by the mould with plaster of paris or insulating material.
The method of heating the mould is of course any convenient source of heat
that happens to be available. It can be done by means of a spirit lamp after the
mould is in position on the cable or the mould can be heated at a fire before being
placed in position on the cable. The heating of the mould if of metal is necessary
to prevent the rapid chilling of the alloy that goes into it, so preventing the
tinning of the connections.
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. A joint for a concentric electric cable formed by baring the ends of each
layer in successive steps down to the central conductor and connecting each pair of
bared conductor ends by means of a separate casting of tin solder or other
conductor into which the ends of the two or more conductors to be joined are well
embedded at a sufficient heat for the solder and conductor to be thoroughly
united.
2. In an electric conductor joint substantially as described in Claim 1, placing in
the mould a strip G of copper or other first class conductor material in close
contiguity with and firmly soldered or brazed to each conductor.
3. In an electric conductor joint substantially as described in Claim 1 splaying
out the ends of the conductors in the mould, in such manner that the solder can
run round and among them and so readily raise them to a sufficient temperature

page_text: for them to firmly unite with it and at the same time, thus form a large electrically
conductor surface between the solder and the conductor.
Dated this 11th day of October 1894.
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Birmingham, Nottingham, and London,
Patent Agents.