Improvements in Junction Boxes for Underground Electrical Conductors.
Year: 1893

page_text: Date of Application, 24th June, 1893-Accepted, 29th July, 1893
COMPLETE SPECIFICATION.
Improvements in Junction Boxes for Underground Electrical
Conductors.
We, DAVID URQUHART and JAMES MILN SMALL, Civil Engineers, of
No. 17 Victoria Street in the City of Westminster, 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 junction boxes for connecting a number of insulated
underground conductors and their branches for the distribution of electrical energy,
our chief object being to construct junction boxes in such a manner that all the
connections of the conductors may be easily and rapidly examined and altered
when required, whilst at the same time they are efficiently insulated.
For this purpose we construct a junction box as we shall describe referring to
the accompanying drawings, which illustrate our invention as applied to a system
of three cables which, at a crossing of two roads, have to be carried onwards and
also branched to right and left.
Fig. 1 is a plan of the junction box for this purpose.
Fig. 2 shews on the right hand a half elevation of the interior and on the left a
half vertical section.
The ends of the insulated conductors A are bent upwards and passed through
holes in a cast iron base B which has extended arms that are built into the walls
of the underground chamber.
They are also passed through holes of a base C made of ceramic or other
suitable insulating material which is fixed to the base B and carefully adjusted to
level by bolts and nuts c.
The ends of the conductors are bared, as indicated at a, and have soldered on
them metal tapered thimbles D, which are tightened by nuts in metal sockets E.
These sockets are steadied in position by studs e projecting down from them into
holes formed in the base C, in which they are cemented.
The holes in the base through which the ends of the conductors pass are
preferably closed at the bottom by cement c' above which they may be charged
with other suitable insulating material by which the bare or uninsulated portions
are efficiently insulated from earth.
Each of the sockets E has bolted to its upright flange a metal link F to which
is also bolted a cross junction bar, the middle bar G straight, the bar G¹ at the one
side bent upwards and G2 at the other side bent downwards, so that, where these
bars cross each other, there is sufficient distance between them to prevent short
circuiting. The whole of these junctions are enclosed within a cover H of sheet
metal, the lower edge of which rests in a deep groove h of the base C, which
groove is filled with oil. We form a pocket K in the base C and place it in a lump
of unslacked lime or other suitable absorbent of moisture, thus ensuring dryness of
the air within the chamber.
To permit the air within the chamber to expand and contract under varying
conditions of temperature and barometric pressure without disturbing the oil in the
groove h, we provide in the bell cover a small air tube L which opens into a box M
containing unslaked lime or other suitable absorbent of moisture.
Instead of the chamber being filled with dry air it may be filled with oil, in
which case the bell cover is provided at its highest point with a small cock or valve.
When, after the connections are made, the bell cover is placed in position, the air
is slowly pumped out of the chamber while the groove is continuously supplied
with oil. When the chamber is thus filled, as indicated by issue of oil at the cock
or valve, this cock or valve is closed leaving the bell full of oil.

page_text: When it is desired to examine or alter the connections, the cock or valve is
opened, the oil then runs out at the groove / which may be provided with a spout h¹
so that the oil can be collected. When the chamber is thus emptied, the cover can
be lifted off, exposing all the connections.
We prefer to support the connecting bars G G G by stands N of ceramic
material, on which any bar rests when a cable is disconnected from it by removing
the connecting link F.
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. A junction box for underground electrical conductors, consisting of a base C
of insulating material and a cover H having its lower edge immersed in oil in a
groove of the base, and in the chamber thus formed detachable links and bars
connecting ends of the cables which are passed up through holes of the base,
charged with insulating material, substantially as herein described.
2. In a junction box such as is above referred to, an air tube through the cover
entering a box containing material absorbent of moisture, substantially as and for
the purpose set forth.
3. The herein described method of filling with oil a junction box such as is
above referred to.
Dated this 24th day of June 1893.
ABEL & IMRAY,
Agents for the Applicants.