Improvements in Safety Fuses or Cut-outs for Electrical Circuits.
Year: 1890

page_text: Date of Application, 21st Aug., 1890
Complete Specification Left, 21st May, 1891-Accepted, 27th June, 1891
PROVISIONAL SPECIFICATION.
Improvements in Safety Fuses or Cut-outs for Electrical Circuits.
I, ARTHUR WILLIAM SLATER, of 10 Lansdowne Place, Blackheath in the
County of Kent, Electrical Engineer do hereby declare the nature of this invention
to be as follows:-
This invention relates to the construction of apparatus known as safety fuses or
cut-outs in clectrical circuits and is effected as follows:
Two small metal tubes are fixed to or let into a block of insulating material.
The metal tubes are provided with lugs for attaching the wires of the circuit to
them by screws or in some cases sockets or thimbles when it is required to attach
the wires of the circuit by solder.
It is convenient in some cases to form the tube and lug or socket in one casting.
The wires of the circuit being connected to the tubes which are insulated from
one another by the block or base which supports them the fuse wire joining them
is attached in the following manner:
A piece of insulating material which may form the cover of the apparatus has
fixed to it two metal plugs of such a size and at such a distance apart as to fit
into the metal tubes.
A hole of a certain diameter is drilled in line through the two metal plugs a
short distance from the insulating piece which holds them.
Each metal plug is split by a fine cut in the same plane as the axes of the holes
to a point just beyond the hole in the direction of the insulating piece which
supports them and the prongs thus formed slightly opened.
A fuse wire of lead tin or other suitable material of slightly larger diameter
than the holes when the prongs are closed is threaded through the two holes and
on inserting the plugs into the tubes the wire is slightly compressed by the prongs
being closed.
In some cases to ensure greater contact a lug or shoulder is cast on the plug and
the hole drilled through the lug..
To ensure a fuse wire of the right section being used should one require replacing
the holes are of one size in the plugs of one diameter and distance apart so that a
fuse wire of too large a section will not go into the holes nor will the plugs of a
larger size apparatus go into the tubes as the diameter and distance apart of the
plugs will be too great.
Dated this Twenty-first day of August One thousand Eight hundred and ninety.
COMPLETE SPECIFICATION.
Improvements in Safety Fuses or Cut-outs for Electrical Circuits.
I, ARTHUR WILLIAM SLATER of 10 Lansdowne Place, Blackheath in the
County of Kent, Electrical Engineer do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
This invention relates to the construction of apparatus known as safety fuses or
cut-outs for electrical circuits and is effected as follows:-
Two small metal tubes are fixed to or let into a block of insulating material.
The metal tubes are provided with lugs for attaching the wires of the circuit to
them by screws or in some cases sockets or thimbles when it is required to attach

page_text: the wires of the circuit by solder. It is convenient in some cases to form the tube
and lug or socket in one casting. The wires of the circuit being connected to the
tubes which are insulated from one another by the block or base which supports
them the fuse wire joining them is attached in the following manner :-A piece of
insulating material which may form the cover of the apparatus has fixed to it two
metal plugs of such a size and at such a distance apart as to fit into the metal
tubes.
A hole of a certain diameter is drilled in line through the two metal plugs a
short distance from the insulating piece which holds them.
Each metal plug is split by a fine cut in the same plane as the axes of the holes
to a point just beyond the hole in the direction of the insulating piece which
supports them and the prongs thus formed slightly opened.
A fuse wire of lead tin or other suitable material of slightly larger diameter
than the holes when the prongs are closed is threaded through the two holes and
on inserting the plugs into the tubes the wire is slightly compressed by the prongs
being closed. In some cases to ensure greater contact a lug or shoulder is cast on
the plug and the hole drilled through the lug."
To ensure a fuse wire of the right section being used should one require replacing
the holes are of one size in the plugs of one diameter and distance apart so that a
fuse wire of too large a section will not go into the holes nor will the plugs. of a
larger size apparatus go into the tubes as the diameter and distance apart of the
plugs will be too great.
The manner in which this invention is carried out will be best understood from
the accompanying drawings.
Figs. 1 2 3 and 4 represent a double pole cut-out made in accordance with this
invention. Figs. 12 and 3 shew respectively a front elevation side elevation and
plan of a double pole cut-out.
Four small metal tubes a¹ a² are embedded in a block 12 of insulating material
such as porcelain each metal tube is formed with a socket or thimble c to connect
the conducting wires to.
The block 2 is made in two pieces divided horizontally in order to imbed the
tubes and sockets. The two portions of the block are secured together by the
screw d.
Figs. 4 and 5 shew the front and side elevation of the cover also made of
porcelain and provided with four metal rods e e². These rods are drilled with a
fine hole near the cover shewn f¹ f2. The rods are split by a fine cut m in the
same plane as the axes of the holes to a point a short distance below the cover and
above the hole thus forming each rod into a split prong.
In order to give sufficient spring in the rods the metal is reduced above the small
hole by drilling a large hole gg2.
The fuse wires h are threaded through the holes f1f2. On inserting the plugs ele
into the tubes a¹ a² electrical contact is made between each pair of sockets through
the fuse wire h.
The small holes f1f2 are rather less in diameter than the fuse wire hand the
effect of inserting the prongs into the tubes is to grip the wire tightly in the
holes flf.
Where a circuit is divided into several smaller circuits the cut-outs are arranged
in the form of a distributing board Figs. 6 7 8 & 9. Fig. 6 represents the front
elevation and Fig. 7 back elevation of one of these boards arranged to divide one
circuit into three smaller circuits.
Fig. 8 represents a section on the line xx and Fig. 9 represents a section on the
line y y
In this case the metal tubes a¹ a² a³ a¹ are let into holes drilled in the base b
which can conveniently be made of slate.
The large circuit is connected on the positive side to the socket k and on the
negative side to the socket l.
The sockets are fixed respectively to the bars n and o.

page_text: The bars are connected by screws and nuts to the tubes a¹ on the positive and
a' on the negative side.
The three small circuits are each connected to the tubes a² a3 by means of the
small sockets c¹ c³.
The arrangement of the prongs carrying the fuse wire shewn in Figs. 10 and 11
is similar in this case to that shewn for the double pole fuse except that each
bridge piece p carries one pair of prongs only.
The circuits are completed through the fuse wire h by inserting the prongs into
the tubes a a² and a¹ a³.
It will be seen that the bridge pieces are interchangeable in the position they
Occupy on the board.
The holes ff2 are all of the same size for the same inside diameter of the
tubes a a² and the distance apart of these tubes a¹ from a² is the same in each case
for circuits of the same size.
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) The construction of a cut-out or safety fuse for electric circuits in which the
fuse wire is carried by two split rods or prongs and passes through a hole in each
and is gripped in the holes when the prongs are closed by being inserted into metal
tubes to which the circuit wires are connected substantially as described.
(2) The construction of a cut-out in which the metal parts carrying current
except the fuse wire and its supports are embedded in a block of insulating material
and the manner of securing the said metal parts in position by dividing the block
horizontally into two portions substantially as described.
(3) The construction of a group of cut-outs or distributing board substantially
as described.
Dated this 21st day of May 1801
ARTHUR WILLIAM SLATER.