Improvements in Electrical Conduits and Conductors.
Year: 1890

page_text: Date of Application, 13th Nov., 1890
Complete Specification Left, 10th Sept., 1891-Accepted 17th Oct
400
VISIONAL SPECIFICATION.
Improvements in Electrical Conduits and Conductors.
I, JOHN MACINTOSH MACKAY MUNRO, of 136 Bothwell Street, Glasgow, in
the County of Lanark, North Britain, Electrical Engineer, do hereby declare the
nature of this invention to be as follows:-
Two or more distinct pipes or culverts are provided of insulating material which
5 may be cement, or bitumen-concrete, or cement-concrete, or brickwork built with
cement, but preferably fireclay pipes, or channels bedded in puddled clay or
cement. One of these is to carry the positive conductors, the other the negative;
the third, if there is a third may assist either, or be partly as spare, or may
three wire system carry the interinediate conductors. Within each of these is laid
one or a bundle of copper tubes. These may be round or slightly flattened into,
in a
say for example, an approximately hexagonal shape so as to economise space.
Each tube is first enamelled outside or coated with any preservative insulating
compound, and is wound with several layers of insulating paper wound on by
preference not spirally, but in wide sheets. This paper is thoroughly mixed and
coated with an insulating varnish of gum, or india-rubber, or gutta-percha, or fluid
bitumen or ozokerite, or paraffin, or such like insulating and waterproof substance.
A spiral layer of thin cloth ribbon is then lapped on as a binding and protection.
Three, five, seven, or other number of tubes are then bound together with care to
preserve the insulation, and the whole bundle is placed within the fireclay pipe or
channel and supported on insulators preferably of wood, glass, or earthenware, so
that there is a clear space all round between the tubes and the channel. This
space is then run in solid with bitumen, and to facilitate this, holes are left, or lids
are provided of such a form that they can be securely luted up by the bitumen, or
otherwise. The tubes may be jointed by slip-over collars which may be distinct
tubes, or may be shaped out of the tubes themselves by pressure or otherwise.
These may be screwed or simply pressed together, and to secure good contact a
non-oxidizable metal may be deposited on the parts of the metal to be in contact,
or these parts may be tinned and be fused together or brazed after laying (and of
course before they are covered by the bitumen) by means of a hydrogen blowpipe
lame or a very large current passed through the joint. The joints may be made
therwise when more convenient, as for example by slotting, punching, or boring
ut indentations in one tube to fit indentations in the one to be joined to it or the
ntermediate coupled piece. But, where space is limited, preferably they are
inted by having the end of one tube cut away to a taper to fit a complimentary
per on its neighbour, and the two are then driven tight together. To hold them
us tight together a key piece is inserted as follows. A slightly dove-tailed slot
s beforehand been cut out of both tubes, and when being laid these slots are
aced so as to meet each other. These slots are slightly bevelled so that the inner
les are wider than the outer although the outer edge is also slightly rounded off.
the slot in each be say 14 inches long by of an inch broad at end furthest from
d of tube and of an inch at end of tube, then for every joint there will be
epared a key 3 inches long by 3 of an inch broad.
o the slots at joint so as to hold the tubes together, but being bevelled on edge
This almost could be dropped
only be introduced from inside tubes. One end is thus placed within slot of
e in position and held there by a mandril, or plug at least as long as the whole
Then the next tube is pushed on and into place, and before withdrawing the
the copper key is hammered on outside of course so as to wedge and dove-tail
If firmly into the slots and so bind the whole together. This joint is analia 11
[Price 8d.1

page_text: to all tubes used for conveying electricity. To secure good contact any of the
devices described above for that purpose may be used. Where there is room, a
sleeve of thin copper tube, which may be split longitudinally, may be drawn over
the joint either within or outwith the conducting tube, or both. These joints are
carefully lapped and insulated like the rest of the tube if they are lapped and
insulated. At intervals of say from 50 to 200 feet are placed fireclay or cement
cast-iron or brick boxes with or without cast-iron covers and in these expansions
connections are provided, also facilities for taking off branches. These expansion
connections may be flexible, stranded, or bent wires or corrugated or bent strips of
copper shaped so as to be easily attached to the ends of the tubes and at the same
time to leave the ends of the tubes open and ready of access. The object of making
these conductor tubes is to facilitate the introduction of additional copper when
required, to afford as large and cool a radiating surface as possible (air may be
blown through the tubes if desired) and also because tubes will transmit expansion
longitudinally to where it can be conveniently dealt with.
Instead of laying the bundles of tubes or insulators, they may be suspended from
insulators and thereafter the interstices may be filled up with bitumen or other
insulating material either with or without paper insulation. The pipes or channels
are now as strong as if solid and well able to stand heavy traffic over them even
when near the surface of the street or pavement..
When otherwise suitable all joints in groups of tubes should be kept together
and be in accessably shaped parts of the pipes, troughs or channels.
Dated this 12th day of November 1890.
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicant's Agents.
COMPLETE SPECIFICATION.
Improvements in Electrical Conduits and Conductors.
I, JOHN MACINTOSH MACKAY MUNRO, of 136 Bothwell Street, Glasgow, in
the County of Lanark, North Britain, 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 :-
Two or more distinct pipes or culverts are provided of insulating material which
may be cement or bitumen-concrete or cement-concrete, or brickwork built with
cement but preferably earthenware (fireclay) pipes or channels bedded in earth or
puddled clay or cement. One of these is to carry the positive conductors, the
other the negative; the third if there is a third may assist either or be partly as
spare, or may in a three wire system carry the intermediate conductors. Within
each of these is laid one or a bundle of copper tubes. These may be round or
slightly flattened into say for example an approximately hexagonal shape so as
to economise space.
Each tube is first enamelled outside or coated with any
preservative insulating compound, and is wound with several layers of insulating
paper wound on by preference not spirally but in wide sheets. This paper is
thoroughly mixed and coated with an insulating varnish of gum or india-rubber or
gutta-percha or fluid bitumen or ozokerite or paraffin or such like insulating and
waterproof substance. A spiral layer of thin cloth ribbon or other insulating
material may then be lapped on as a binding and protection. One, three, five,
seven, or other number of tubes are then bound together with care to preserve the
insulation, and the whole bundle is placed within the fireclay pipe or channel and
supported on insulators preferably of prepared wood glass or earthenware, so that
there is a clear space all round between the tubes and the channel. This space
then run in solid with bitumen, and to facilitate this holes are left or lids are
provided of such a form that they can be securely luted up by the bitumen or
otherwise. The copper tubes may be jointed by slip-over collars which may be

page_text: 5
oes or may be shaped out of the tubes themselves by pressure
otherwise. These may be screwed or simply pressed together and to secure goo
contact a non-oxidizable metal may be deposited on the parts of the metal to be i
contact or these parts may be tinned and be fused together or brazed after layin
(and of course before they are covered by the bitumen if bitumen is to be used) b
means of a hydrogen blowpipe flame or a very large current passed through th
joint. The joints may be made otherwise when more convenient, as for exampl
by slotting, punching, or boring out indentations in one tube to fit indentations in
the one to be joined to it or the intermediate coupled piece. But where space i
10 limited preferably they are jointed by having the end of one tube cut away to a
taper to fit a complimentary taper on its neighbour, and the two are then driven
tight together. To hold them thus tight together a key-piece is inserted as follows.
A slightly dovetailed slot has beforehand been cut out of both tubes and when
being laid these slots are placed so as to meet each other. These slots are slightly
5 bevelled so that the inner sides are wider than the outer although the outer edge is
also slightly rounded off. If the slot in each be say 14 inch long by of an inch
broad at end furthest from end of tube and of an inch at end of tube, then for
every joint there will be prepared a key 3 inches long by of an inch broad. This
almost could be dropped into the slots at joint so as to hold the tubes together, but
being bevelled on edge can only be introduced from inside of tubes. One end is
thus placed within slot of tube in position and held there by a mandril or plug at
least as long as the whole key. Then the next tube is pushed on and into place,
and before withdrawing the plug the copper key is hammered or pressed (op outside
of course) so as to wedge and dovetail itself firmly into the slots and so bind the
whole together. This joint is applicable to all tubes used for conveying electricity.
To secure good contact any of the devices described above for that purpose may be
used. Where there is room a sleeve of thin copper tube which may be split
longitudinally may be drawn over the joint either within or outside the conducting
tube or both. These joints are carefully lapped and insulated like the rest of the
tubes if they are lapped and insulated. At intervals of say from 50 to 200 feet are
placed fireclay or cement cast-iron or brick boxes (called drawing-in boxes) with or
without cast-iron covers, and in these expansion-connections are provided, also
facilities for taking off branches. These expansion connections may be flexible,
stranded, or bent wires or corrugated or bent strips of copper shaped so as to be
easily attached to the ends of the tubes, and at the same time to leave the ends of
the tubes open and ready of access.
form of tubes is to facilitate the introduction of additional copper when required, to
The object of making these conductors in the
afford as large and cool a radiating surface as possible (air may be blown through
he tubes if desired) and also because tubes will transmit expansion longitudinally
o where it can be conveniently dealt with.
Instead of laying the bundles of tubes or insulators on supports placed underneath
hem they may be suspended from insulators, and thereafter the interstices may be
lled up with bitumen or other insulating material either with or without paper
sulation. The pipes or channels are now as strong as if solid, and well able to
and heavy traffic over them even when near the surface of the street or pavement.
nder ordinary street traffic or where the conduits are strongly made the suspended
be may be insulated by air space only no bitumen being used. The tubes inay in
is case be entirely bare or they may be painted or enamelled with colours which
ile of some protection against oxidizing also assists in identifying special wires.
hen the tubes are thus mainly air insulated the points of support should be as
as possible, and should as far as convenient be of the suspension type, and the
es themselves should be kept apart by insulators as of glazed earthenware.
When otherwise suitable all joints in groups of tubes should be kept together and
in accessably shaped parts of the pipes, troughs or channels. It is well when
positions of the joints in air insulated tubes coincide with all or some of the
nts of support so that it may be practicable at such points to provide roomy
pension or joint boxes for more convenient access.

page_text: In order that my invention may be properly understood and more readily carried
into effect I hereunto append four explanatory sheets of drawings.
Figure 1 is a section of a conduit showing the tubular conductors embedded in
insulating material preferably bitumen, of which P is the fireclay pipe, T the
tubular conductors, S the support, and B the bitumen.
Figure 2 is a longitudinal section of a joint or suspension box as used for
conduits for trunk mains; and Figure 2 is a transverse section taken on the
line a b.
Pare the fireclay pipes, S B the suspension or joint box which is also made of
fireclay and cemented to the pipes P by Portland cement P'; C is the cover which
is lightly cemented on to the box; IL is the inner lid, and O L the outer lid
having a space between them for waterproof substance, the outer lid also being
luted at L. These lids are easily accessible from the street, their position being
known. CT are the copper conducting tubes, and CP the connecting pieces of
copper tube which are tinned inside and have a few small holes to facilitate
soldering. A star E' of porcelain is then pushed along to centre of joint, and other
earthenware pieces E are placed in position and bound together by a binding
strap B S, and the whole is then suspended by S from a crossbar B resting on
insulators I, I provided with grooves for fluid insulation. D is the drip protecting
insulator against possible leakage of water into the box. A S is the air space
round tubes in pipes, and A' S₁ the air round the supports.
Figure 3 shows the appearance when laid of a conduit of glazed earthenware for
trunk mains (the positive and negative conductors being preferably in separate
conduits) of which P are the pipes, and B the suspension or joint boxes.
The drawing-in boxes, which are placed from 50 to 300 feet apart, and are of
cast-iron, brick, cement, or other suitable material, are not shown in Figure 3, but
are illustrated in Figure 4, which shows a part of a conduit and a cast-iron
drawing-in box as adapted for trunk mains of a three wire system; and Figure 4^
is another view of the drawing-in box. The method of suspension and connection
of copper tubular conductors within the cast-iron drawing-in box is illustrated at
Figure 4 (where only the negative conductors are shown, the other being omitted
for clearness). T are the copper tubes, and V the supports for insulators, having
hoods, and screwed to box. B are the suspension rods carrying the suspension
straps S, and I are the insulators on which the suspension rods rcst. P₁ are the
connecting pieces to allow of expansion of tubes and access for drawing in additional
copper within tubes.
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 system of electrical conduits for underground use in which tubular
conductors are placed within earthenware conduits.
2. A system of electrical conduits for underground use in which separate
earthenware conduits are provided for conductors of widely differing potential.
3. In a system of underground electrical conductors, the use of tubes of copper,
aluminium, or other metal, substantially for the purpose and in the manner
described with reference to Figures 1 and 2.
4. The method of insulation and support for tubular conductors substantially as
described with reference to Figure 1.
5. The method of insulation and support for tubular conductors substantially as
described with reference to Figures 2 and 4.
6. The combination of tubular conductors with expansion coupling pieces
substantially as illustrated with reference to Figure 4.
7. Joint or suspension boxes substantially as described with reference to
Figures 2 and 2^.
8. The combination of earthenware conduits with suspension or joint boxes,
substantially as described with reference to Figure 3.

page_text: me combination of double or multiple conduits of earthenware, brickwork,
cement, or other insulating or semi-insulating material with conductors substantially
as described placed so that those of widely differing potential are in distinct
conduits or divisions of conduit.
Dated this 9th day of September 1891.
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicant's Agents.