Improvements in and relating to Conduits for Electrical Conductors and Joints therefor.
Year: 1897

page_text: Date of Application, 8th Jan., 1897
Complete Specification Left, 8th Oct., 1897-Accepted, 13th Nov., 1897
Improvements in and relating to Conduits for Electrical Conductors
and Joints therefor.
I, FREDERICK BATHURST, of No. 14 Greencroft Gardens, South Hampstead, in
the County of Middlesex, Electrical Engineer, do hereby declare the nature of
this invention to be as follows:-
My invention relates to certain improvements in and relating to conduits for
electrical conductors, and joints therefor, and has for its objects the better pro-
tection of the enclosed conductor, and the provision of ready means for joining
several lengths of standard sizes, to form a continuous length, of even surface and
diameter.
In carrying my invention into effect I employ a tube of any suitable insulating
substance, composition, or material, and by means of dies, and proper appliances
for drawing, such as employed in the bedstead making trade for making what is
known as
open joint tube," I thus cause a strip of steel or other metal to be
drawn upon said insulating tube so as to cover it tightly, and form a metallic
armouring. The width of the strip of steel or other metal is arranged so that the
action of drawing causes the two edges to approximately touch each other through-
out the length of the piece of conduit. The slight longitudinal opening, is
however unavoidable, and if not protected might afford an entry for nails or
screws, which would shortcircuit or otherwise injure the enclosed conductors.
In order to obviate this, I cause a second strip of metal to be drawn over the
first, in such a manner that the longitudinal slit between the edges is diametrically
opposite that of the first covering.
In this manner, by the use of an inner and an outer steel or other metallic
covering I am enabled to afford a perfectly continuous armouring, and also secure
hermeticity, in addition to immunity from damage by puncture.
In jointing two lengths of conduit made in the manner hereinbefore described,
I cut away, by means of a suitable stripping tool, a short length of the outer
armoring at the end of each length or piece of conduit to be joined. A shoulder
is thus formed by the faced edge of the outer armoring, where cut lack, and the
face of the inner armoring and the insulating tube is flush, so that when both
pieces of conduit are brought together they may abut. A short sleeve of metal,
the outer diameter of which is equal to that of the outer armoring, and the
inner diameter made to fit very tightly upon, the projecting piece of inner armoring,
is forced upon the latter, on one of the pieces of conduit to be joined, so that
it projects beyond the abutting edge of the inner armouring sufficiently to allow
the other piece of conduit to be forced into it, and when the coupling sleeve
meets the shoulders formed by the stripped outer armouring, the inner armouring
and the insulating tube shall abut. Thus a perfectly continuous conduit is pro-
vided, with a regular and even surface inside and outside. I may arrange the
inner diameter of the coupling sleeve to be shrunk upon the ends prepared for it

page_text: by raising its temperature, but not to a degree approximating that of the melting
point of the internal insulating tube. The junction of the said internal insulating
tube may be effected by allowing the two ends merely to abut, or the coupling
sleeve may be fitted internally with a suitable insulating bushing piece.
I may modify the means for fixing the coupling sleeve aforesaid, by using
auxiliary attachments to ensure rigidity, such as pins, screwing, soldering, or the
like.
The essential features of my said invention are in the production of an im-
pervious armored and insulated conduit, which when joined together in lengths
shall form a continuous and even surface externally and internally, and preserving
hermeticity.
FREDK. WALKER,
73 St. Stephen's Road, Upton Park, London, E.C.,
Agent for the Applicant.
Improvements in and relating to Conduits for Electrical Conductors
and Joints therefor.
I, FREDERICK BATHURST, formerly of No. 14 Greencroft Gardens, South Hamp-
stead in the County of Middlesex, now of No. 4 Limes Villas, West Hill Road, 2
S.W. 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:—
My invention relates to certain improvements in, and connected with conduits
for electrical conductors and joints therefor, and has for its objects the better 2
protection of the electrical conductor enclosed within it, and the provision of
ready means for joining together several lengths of standard sizes to form a
continuous length of even surface and diameter.
In order that my invention may be the better understood, I have appended the
accompanying sheet of drawings, in which Figure 1 is a perspective view of a 3
piece of the insulating interior conduit with the first metal sheathing partially
enclosing it. Figure 2 shows the first sheath closed, and the second, with opposite
junction partially wrapped round it. Figure 3 is a sectional view of both sheaths
closed, showing opposite junctions. Figure 4 is an elevation of a sleeve joint,
and Figure 5 is a section of the same. Similar letters of reference indicate corre-
sponding parts throughout the several views.
In carrying my invention into effect I employ a tube a of any suitable insulat-
ing substance, composition, or material, and by means of dies, and proper appliances
for "drawing" such as used in the bedstead making trade for forming what is
known as
open joint tubing," I thus cause a strip of steel or other metal b
Figures 1, 2 and 3, to be drawn upon said insulating tube a so as to cover it
tightly and form a metallic armouring. The width of the strip b is arranged so
that the action of drawing causes the two edges to approximately touch each
other as e forming a joint throughout the length of the piece of conduit. The
slight longitudinal opening at el is, however unavoidable, and if not protected
might afford an entry for screws or nails, which would short circuit or otherwise
injure the enclosed conductors. In order to obviate this, I cause a second strip
of metal c, Figures 2 and 3, to be drawn over b in such a manner that the longi-
tudinal slit e formed by the closure of the edges is diametrically opposite to the

page_text: corresponding slit e¹ in b.
Figure 3.
This is clearly shown by the transverse section
In this manner, by the use of an inner metal sheath and an outer metal
sheath I am enabled to construct a continuous armoured conduit, securing
hermeticity in the conduit proper, represented by the insulating tube and
preventing the deterioration incidental to puncture.
a,
In jointing two separate lengths of conduit made in the manner hereinbefore
described, I cut away by means of a suitable stripping tool a short length of the
outer armouring c (Figures 4 and 5) at the end of each piece or length of conduit
to be joined. A shoulder is thus formed by the face of the outer armouring e
where cut back, and the faces of the inner armouring c and the insulating tube a
A short
are brought together so that they may abut as shown by Figure 5.
sleeve of metal, the outer diameter of which is equal to that of the outer
armouring c and the bore fitting the inner armouring b is made to fit tightly
upon the projecting ends of. said inner armouring b, and is forced upon one end
of the two pieces to be joined, and the other piece is inserted so that all the
edges abut, and a regular and even surface is produced interiorly and exteriorly.
ihe inner diameter or bore of the coupling sleeve d may be slightly less than
the outer diameter of b, so that when expanded by heat it may be shrunk upon the
two ends of b, the heat always being below the degree at which the inner insulating
tube a becomes soft or melts.
I may modify the means for fixing the sleeve joint or coupling, by using
auxiliary attachments, such as pins, screw threads soldering brazing, or other
means to secure rigidity.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:
First. In electrical conduits, the method of enclosing an inner insulating tube
witbin a metallic sheathing or armouring, with an open joint, and enclosing this
in another metallic sheathing or armouring, the open joint of which is oppositely
placed relatively to the first, substantially as herein described, and shown by the
accompanying sheet of drawings.
Second. In electrical conduits as referred to in the preceding claim, the method
of, and means for jointing two separate pieces by stripping the outer armouring or
sheathing, and fitting a sleeve upon the inner armouring or sheathing making a
plain and even joint internally and externally, substantially as herein described
with reference to Figures 4 and 5 of the accompanying sheet of drawings.
Dated this 5th day of October 1897.
FREDK. WALKER,
73 St. Stephen's Road, Upton Park, London, E.,
Agent for the Applicant.