IMPROVEMENTS IN ELECTRICAL CONDUCTORS
Year: 1884

page_text: I THOMAS JOHN HANDFORD of 42 Southampton Buildings in the County of
Middlesex Patent Agent do hereby declare the nature of this invention for
"IMPROVEMENTS IN ELECTRICAL CONDUCTORS" a communication to me from
abroad by Edward Hibberd Johnson of the City, County and State of New
York United States of America, Electrician, to, be as follows:-
The object of this invention is to produce a method of arranging and insulating
electrical conductors, more especially adapted and designed for wiring houses, ships
and other structures for the electric light, and the wiring of fixtures for supporting
incandescing electric lamps which will make it possible by the employinent of
fusible safety catches to prevent absolutely the setting of fire by leakage of the
current.
Heretofore it has been considered conducive to safety to separate the two
conductors of an electric light circuit a considerable distance, but experience has
shewn that when this is done leaks between the conductors will occur through
intervening material which may be ignited by the formation of a high resistance
are without fusing the safety catches designed to protect the circuit:
My foreign correspondent, however, has discovered that by bringing the conduc-
tors close together and so arranging and constructing them that any imperfection.
of the insulation will immediately establish an are between the conductors them-
selves of such low resistance as to amount to a practical short circuit, the safety
catches will be invariably fused and the circuit broken before damage can occur.
The most perfect insulators of electricity known to the art and those that are
proof against moisture are oils or gums which are inflammable. But by the .
methods heretofore employed for insulating the separated conductors it has been
found impracticable to use these more perfect and waterproof insulators on account
of their inflammability, and noncombustible insulating coverings have been
employed which by reason of being less perfect insulators permit the formation
of dangerous leaks.
By this invention it becomes possible to insulate the conductors from each othér
by the most perfect waterproof materials for the purpose, regardless of their

page_text: inflammable nature, and also to employ the non-inflammable insulators between
the conductors and the structure upon which the conductors are supported, and
where their inferior insulating properties are of less importance.
At the same time that these desirable ends are attained the flexibility of the
conductors is preserved making them suitable for the wiring of houses and other
structures and fixtures, and the conductors are in such form that it is convenient
to make the connections required in running circuits.
In carrying out the invention a compound conductor is provided having the two
conductors of a complete or round metallic circuit enclosed in a common insulating.
covering which is a non-inflammable insulation of any suitable character, such as a
braided woven or knit cotton covering impregnated with white lead or other
non-inflammable material. Within the covering the conductors are arranged so
that one forms a complete metallic shield for the other and the two conductors
are separated by the most perfect waterproof insulation without regard to its
inflammable nature, such as paraffine or rubber, or other moisture excluding
material such as bitumen or a fabric 'impregnated with these or any other
material of this nature.
The core of the compound conductor is a wire or a bunch of wire, covered
carefully with the paraffine, rubber or similar insulation. The other conductor is
composed of a number of bare wires of such a size that they can be placed over
the inner conductor and, its insulation, and will forin a complete metallic shield,
and at the same time will have the same current conducting capacity as the inner
conductor, or preferably will be a greater mass of metal and have more current-
conducting capacity than the inner conductor. These naked wires are preferably
wound spirally upon the inner insulated conductor in one layer, the spiral winding
being preferred to prevent kinking in use although the wire composing the outer
conductor may be laid parallel with the inner conductor.
In lieu of using a number of wires for the outer conductor it may be composed
of one or more flat strips wound spirally upon the inner insulated conductor and
forming a complete metallic shield for the same.
By reason of the arrangement of the outer conductor as a shield for the inner
conductor, the said outer conductor must necessarily have a less thickness, at any
one point than the inner conductor, and it might be possible for the current in
arcing between the conductors to blow a hole through the outer conductor without
fusing the safety catch, resulting in weakening the outer conductor at that point
and causing it to be heated by the current which continues to flow. This objection
to the arrangement of the conductors described is overcome by interposing between
the outer and inner conductors and in contact with the outer conductor a thin body
of metal the fusing point of which is lower than that of copper. This thin body
of metal may be lead covering placed upon the insulation of the inner conductor in
any of the known ways of covering insulated wire with lead. It is preferably
quite thin and should embrace the insulation of the inner conductor closely, and
this insulation of the inner conductor is also preferably as thin as it can be made
practically.
"
The body of easily fusible metal in lieu of being a solid tube of lead as usual in
covering wire with lead may be made of lead or tin foil wound upon the insulation
of the inner conductor.
The bare wires forming the outer conductor are laid directly upon this covering
of lead or equivalent material, which in the arcing of the conductors fuses before
the copper and forms an arc of the required low resistance to fuse the safety
catches.
This lead or equivalent covering may be dispensed with and the outer conductor
he wound directly upon the insulation of the inner conductor, but it is preferred to
use the lead or equivalent covering for the reason already stated.
An additional advantage of the lead or equivalent covering is that it increases
the current carrying capacity of the outer conductor so that in carrying an
abnormal current the inner conductor will become heated before the outer con-
+

page_text: ductor is. The advantages of the lead or equivalent covering may be largely
obtained when it is dispensed with by enlarging the mass of the outer conductor
and increasing its conductivity, and this may also be done even when the lead or
equivalent covering is used.
After the lead or equivalent covering and the outer conductor are placed upon
the inner insulated conductor, the whole is covered as before explained by a non-
inflammable insulation, such for example as a cotton covering impregnated with
white lead or other fireproof material.
The compound conductor is used with fusible safety catches placed in one or in
each side of the circuit at the point of departure of smaller from larger conductors.
It will be seen that there can be no contact of the inner conductor with any
external object except through the outer conductor. The breaking down of the
insulation separating the conductors will with certainty produce an arc of such low
resistance as to effect a short circuit between the conductors, instantly fusing the.
safety catch or safety catches protecting the particular conductors and breaking the,
circuit.
This compound conductor also possesses the advantage of cheapening to a large
extent the cost of wiring houses and other structures for electric light, since
provision only has to be made for one conductor and the labour is equivalent to
the laying of one conductor only. For wiring fixtures and especially combination
gas and electric light fixtures the impossibility of forming an, arc between the
conductors and outside material, as the metal of the fixture, removes a constant
danger which had heretofore been an obstacle in the way of fixture work.
In making connections with the compound conductor, the outer conductor is
unwound from the inner conductor to the desired extent and the inner conductor
laid bare. The wires forming the outer conductor can be twisted together by
hand, and a good and secure electrical and mechanical connection can be made
with them.

page_text: I THOMAS JOHN HANDFORD of 42 Southampton Buildings in the County of
Middlesex, Patent Agent do hereby declare the nature of this invention for
"IMPROVEMENTS IN ELECTRICAL CONDUCTORS" and in what manner the same is
to be performed,, to be particularly described and ascertained in and by. the
following statement :-
The object of this Invention is to produce a method of arranging and insulating
electrical conductors, more especially adapted and designed for wiring houses, ships
and other structures for the electric light, and the wiring of fixtures for supporting
incandescing electric lamps, which will make it possible by the employment of
fusible safety-catches to prevent absolutely the setting of fire by leakage of the
current.
Heretofore it has been considered conducive to safety to separate the two
conductors of an electric light circuit a considerable distance, but experience has
shown that when this is done, leaks between the conductors will occur through
intervening material which may be ignited by the formation of a high resistance
arc without fusing the safety-catches designed to protect the circuit.
My foreign correspondent however has discovered that by bringing the con-
ductors close together and so arranging and constructing them that any imperfection
of the insulation will immediately establish an arc between the conductors them-
selves of such low resistance as to amount to a practical short-circuit, the safety-
catches will be invariably fused, and the circuit broken before damage can occur.
The most perfect insulators of electricity known to the art and those that are
proof against moisture, are oils or gums which are inflammable.
But by the methods heretofore employed for insulating the separated conductors
it has been found impracticable to use these more perfect and water-proof insulators
on account of their inflammability; and non-combustible insulating coverings have
been employed which by reason of being less perfect insulators permit the formation
of dangerous leaks.
.
By this Invention it becomes possible to insulate the conductors from each other
by the most perfect water-proof materials for the purpose regardless of their
inflammable nature, and also to employ the non-inflammable insulators between
the conductors and the structure upon which the conductors are supported and
where their inferior insulating properties are of less importance.
At the same time that these desirable ends are attained the flexibility of the
conductors preserved making them suitable for the wiring of houses and other
structures, and fixtures, and the conductors are in such form that it is convenient
to make the connections required in running circuits.
In carrying out the invention, a compound conductor is provided having the two
conductors of a complete or round metallic circuit inclosed in a common insulating
covering, which is a non-inflammable insulation of any suitable character such as
a braided, woven or kuit cotton covering impregnated with white lead or other
non-inflammable material.
Within the covering the conductors are arranged so that one forms a complete
metallic shield for the other, and the two conductors are separated by the most

page_text: perfect water-proof insulation without regard to its inflammable nature, such as
paraffine or rubber, or other moisture-excluding material, such as bitumen, or a
fabric impregnated with these or any other material of this nature.
The core of the compound conductor is a wire or a bundle of wires, covered
carefully with the paraffine, rubber or similar insulation.
"
The other conductor is composed of a number of bare wires of such a size that
they can be placed over the inner conductor and its insulation and will form a
complete metallic shield, and at the same time will have the same or approximately
the same current conducting capacity as the inner conductor, or preferably will be
a greater mass of metal and have more current. conducting capacity than the inner
conductor.
These naked wires are preferably wound spirally upon the inner insulated
conductor in one layer, the spiral winding being preferred to prevent kinking in
use, although the wires composing the outer conductor may be laid parallel with
the inner conductor.
In lieu of using a number of wires for the outer conductor, it may be composed
of one or more flat strips, wound spirally upon the inner insulated conductor and
forming a complete metallic shield for the same.
By reason of the arrangement of the outer conductor as a shield for the inner
conductor, the said outer conductor must necessarily have a less thickness at any
one point than the inner conductor, and it might be possible for the current in
arcing between the conductors to blow a hole through the outer conductor without
fusing the safety-catch, resulting in weakening the outer conductor at that point
and causing it to be heated by the current which continues to flow.
This objection to the arrangement of the conductors described is overcome by
interposing between the outer and inner conductors and in contact with the outer
conductor, a thin body of metal the fusing. point of which is lower than that of
copper.
This thin body of metal may be a lead covering placed upon the insulation of
the inner conductor in any of the known ways of covering insulated wire with
lead.
It is preferably quite thin and should embrace the insulation of the inner
conductor closely, and this insulation of the inner conductor is also preferably as
thin as it can be made practically.
The body of easily fused metal in lieu of being a solid tube of lead as usual in
covering wire with lead may be made of lead or tin foil wound upon the insulation
of the inner conductor.
The bare wires forming the outer conductor are laid directly upon the lead
covering, which in the arcing of the conductors fuses before the copper and forms
an arc of the required low resistance to fuse the safety-catches.
This lead covering may be dispensed with and the outer conductor be wound
directly upon the insulation of the inner conductor; but it is preferred to use the
lead covering for the reasons already stated.
An additional advantage of the lead covering is that it increases the current
carrying capacity of the outer conductor so that in carrying an abnormal current
the inner conductor will become heated before the outer conductor is.
The advantages of the lead covering may be largely obtained, when it is dispensed
with, by enlarging the mass of the outer conductor and increasing its conductivity,.
and this inay also be done even when the lead covering is used.
After the lead covering and the outer conductor are placed upon the inner
insulated conductor, the whole is covered as before explained by a non-inflammable
insulation, such for example as a cotton covering impregnated with white lead or
other fire-proof material.
f
The compound conductor is used with fusible safety-catches placed in one or in
each side of the circuit at the point of departure of smaller from larger conductors.
It will be seen that there can be no contact of the inner conductor with any
external object except through the outer conductor,

page_text: The breaking down of the insulation separating the conductors will with certainty
produce an arc of such low resistance as to effect.a short-circuit between the con-
ductors, instantly fusing the safety-catch, or safety-catches protecting the particular
conductors, and breaking the circuit.
This compound conductor also possesses the advantage of cheapening to a large
extent the cost of wiring houses. and other structures for electric light, since
provision only has to be made for one conductor, and the labour is equivalent to
the running of one conductor only. For wiring fixtures and especially combination
gas and electric light fixtures, the impossibility of forming an arc between the con-
ductors and outside. material, as, the metal of the fixtures, removes a constant
danger which has heretofore been an obstacle in, the way of fixture work:
In making connections with the compound conductor, the "outer conductor is
unwound from the inner conductor to the desired extent, and the inner conductor
laid bare. The wires forming the outer conductor can be twisted together by hand
and a good and secure electrical and mechanical connection can be made with them.
In the accompanying drawing, forming a párt hereof
Figure I, represents an elevation of the compound conductor partially stripped
to show its construction.
Figure 2, a cross section on a larger scale of the compound conductor; and
Figure 3, a view showing the conductor in use.
A, is the inner conductor; B, is the high water-proof insulation of paraffine,
rubber or similar material placed thereon; C is the lead covering of the inner
conductor; D, is the outer conductor arranged to shield mechanically the inner
conductor; and E, is the fire-proof insulation forming the outer covering of the
compound conductor.
Referring to figure 3, the compound conductors 1, 2 and 3 are shown as joined
in an electric light circuit. 1 is larger than 2 and 3, which form branches of 1.
At the point of departure of the smaller from the larger conductors, the fusible
safety-catches a bare introduced into the circuit. These are proportioned to
protect 2 and 3. 1 is protected by fusible safety-catches where it branches from
larger conductors or at the dynamo machine. if it proceeds directly therefrom.
Having now particularly described and ascertained the nature of the said
Invention, and in what manner the same is to be performed, I declare that what
I claim is
1st A flexible compound conductor composed of an inner or core conductor
covered with insulation, an outer conductor surrounding and forming a shield for
the inner conductor and an external fire-proof insulation, substantially as herein-
before described.
2nd A flexible compound conductor composed of an inner conductor covered
with water-proof insulation, an outer conductor surrounding and shielding the
inner conductor and an external fire-proof insulation, substantially as hereinbefore
described.
3rd A compound conductor composed of an inner conductor, an outer conductor
surrounding the inner conductor and insulated therefrom, and a body of easily
fused metal interposed between the conductors, substantially as hereinbefore
described.