Improvements in Electrical Conducting Mains.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Electrical Conducting Mains.
We, JOHN SOMERVILLE HIGHFIELD, of No. 34, Wolseley Road, St. Helens, in
the County of Lancaster, Electrical Engineer, and JOHN MCILVAINE CATER, of
Southdown, The Downs, Wimbledon, in the County of Surrey, Electrical
Engineer, do hereby declare the nature of this invention to be as follows:-
Our invention relates to electrical conducting mains of simple and compact
form, readily accessible for making connections.
For this purpose, when the mains are to be on the three wire system we make
two of the conductors with a transverse section approximately in the form of a
segment of a circle having a dovetail groove extending longitudinally along the
crown of the segment. The third conductor has a section of the form of a deep
double headed rail with the dovetail groove running along one of the heads.
These conductors are covered with insulating material, such as compressed fibre,
and are bedded in insulating material, which may be hard wood, within a pipe,
the two segmental conductors having their flat faces parallel to one another,
and the other conductor being situated between them. In some cases this
middle conductor may be dispensed with, as when the two wire system is used, or
when the pipe serves as the third wire. On the outside of the pipe are small
grooves facing the dovetail grooves in the conductors, so that when a connection
has to be made, the workman knows where to drill into the pipe to reach those
grooves. In making a connection, a hole is drilled through the metal of the pipe
and the wood till the drill reaches the conductor and in the hole of the pipe is
screwed a short tube containing insulated within it a connecting piece which is
split at its end and has a wedge inserted in the split. This end is driven into
the dovetail groove of the conductor, the wedge expanding it so that it takes
firm hold in the dovetail. The service connections may be made to the piece in
any suitable way.
Instead of making the conductors with dovetail grooves as described, they
might be made without these grooves, and in that case when connections are
made to them, holes are drilled in them and tapped and the connecting pieces
are screwed into these holes.
Although we have described two of the conductors as being of section approxi-
mately a segment of a circle, these might be of other forms presenting flat sides
towards each other and middles sufficiently thick to receive the dovetail grooves
or the screwed connections.
The mode of making a connection by wedging in a dovetail groove or by
screwing the connecting pieces into a hole in the conductor may obviously be
employed when there is only one conductor in the pipe.
Dated this 21st day of October 1898.
ABEL & IMRAY,
Agents for the Applicants.

page_text: Improvements in Electrical Conducting Mains.
We, JOHN SOMERVILLE HIGHFIELD, of No. 34, Wolseley Road, St. Helens, in
the County of Lancaster, Electrical Engineer, and JOHN MCILVAINE CATER, of
Southdown, The Downs, Wimbledon, in the County of Surrey, 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:-
Our invention relates to electrical conducting mains of simple and compact
form readily accessible for making connections, as we shall describe referring to
the accompanying drawings.
'
_1
Fig. 1 is a transverse section of a conducting main suited for the three wire
system.
Fig. 2 is a section shewing the separate conductors modified in form, and
shewing also a connection to one of them. Fig. 3 shews a detail.
;
As shewn in Fig. 1 each of two of the conducting bars a have a transverse
section approximately in the form of a circular segment with a dovetail groove b
formed in the course of the segment and extending along its whole length.
The third conducting bar a' has the form of a deep double headed rail with the
dovetail groove in one of the heads.
Each of these conducting bars is covered with a layer c of any suitable insu-
lating material such for instance as compressed fibre and are bedded in insulating
material which may be bars d of wood cut to shape. The whole is enclosed
within a metal pipe e which has along its exterior a small groove f directly
facing each of the dovetail grooves b.
As shown in Fig. 2 the three conducting bars a are all alike of modified form,
approximately trapezoidal. They have the dovetail grooves the insulating
coating c and are bedded in wood & enclosed within a metal pipe c.
When it is desired to make a connection to any one of the conductors a hole
is bored through the metal of the pipe, the centre of the hole being in the
groove and therefore in line with the middle of the dovetail groove of the con-
ductor. The hole is internally screw threaded. A connecting piece 'g having
its end split and a wedge inserted in the split is then driven in, and the wedge
being thus forced up the split, expands the sides of the split so as to make them
fit and hold firmly in the dovetail; around the stem of a wooden sleeve mis
put on in halves." A conducting branch being soldered into the socket 'end
of the connecting piece g and this piece being coated with 'insulating material
an enclosing socket 1, lined with insulating material where it surrounds mis
screwed into the hole of the pipe e and its interior is filled around g with molten
insulating material such as pitch.
As the middle conducting bar 21 of Fig. 1 requires only one groove, it may
have the shape of a single headed rail.
In order to form the dovetail grooves in the bars a of Fig. 2 these bars may
be first rolled to a shape such as indicated by dotted lines in Fig. 3 with a groove
which is not dovetailéd. Then, on passing the bar through between suitable
rollers, it is bent laterally so as to bring the outer edges of the groove nearer to
each other thus giving it the dovetailed form.
In like manner the grooves of the bars a of Fig. 1'may be dovetailed, and the
groove of may be first rolled without the dovetail form which can then be
obtained by passing the rail head between squeezing rollers.

page_text: The pipe e is preferably made with an internal rib n to prevent the conductors
from turning round within it.
When the pipe e is used as return conductor or middle wire or when the line
is on the two wire system one of the bars is dispensed with. When two pairs
of conductors are required, a fourth bar a can be introduced where the space is
shewn empty, the four conductors being then arranged symmetrically.
Successive lengths of pipe e with conductors arranged in them being placed
end to end with the conductors projecting beyond their ends, the conductors
can be connected by sleeves soldered on them, and these connections being
covered with insulating material, the pipes can be joined by screw sockets or
otherwise.
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:-
1. An underground electric conducting line consisting of several metal bars
each having a dovetail groove along its wider side, these bars being coated with
suitable insulating material and packed with their grooves outwards between
suitably shaped wooden bars within a metal pipe having along its exterior a
groove facing each of the said dovetail grooves, substantially as described.
2. In combination with a conducting bar having a dovetail groove along one
side and packed within a metal pipe with its groove presented towards the cir-
cumference of the pipe, a connecting conducting piece having a split end with
a wedge in the split, the said end being adapted to be driven through a hole in
the pipe into the dovetail groove and expanded therein, substantially as and for
the purposes set forth.
Dated this 21st day of July 1899
ABEL & IMRAY,
Agents for the Applicants.