Improvements in or relating to Metallic Junction Boxes or Cases for Conductors or Fittings for Electric Lighting, Electric Bell Circuits, and like purposes, and in the Mode of Connecting the Conductors thereto.
Year: 1891

page_text: Date of Application, 6th Oct., 1891
Complete Specification Left, 30th Jan., 1892-Accepted, 5th Mar., 1892
PROVISIONAL SPECIFICATION.
Improvements in or relating to Metallic Junction Boxes or Cases
for Conductors or Fittings for Electric Lighting, Electric Bell
Circuits, and like purposes, and in the Mode of Connecting the
Conductors thereto.
We, HENRY ALEXANDER MAVOR, WILLIAM ARTHUR COULSON and
SAM MAVOR of the firm of Mavor and Coulson, Electrical Engineers, and
WILLIAM BROOKS SAYERS Electrical Engineer all of 56 George Square
Glasgow in the County of Lanark do hereby declare the nature of this invention
to be as follows:-
This invention which relates to metallic junction boxes or cases for concentric
and other conductors or fittings for electric lighting, electric bell circuits and like
purposes and to the mode of connecting conductors thereto has for its object to
provide improved means of connecting the head or other external part or sheathing
of the conductors to the junction boxes or cases and whereby any risk of damp or
moisture seeking or searching back from the junction box or case along the
insulating coating of the central conductor in either direction is obviated whilst at
the same time the improved construction greatly facilitates the making of the
connection and the insertion of apparatus within the junction box or case by
enabling the work to be performed from above.
Under one form of the invention the junction box or case is at each end where
the conductors are led in formed with a projecting neck or support which is
U shaped in cross section the opening being upwards. Into these necks the cables
or conductors are laid and between the end of the neck next to the hollow central
portion or body of the junction box or cuse a pocket or part of greater width and
depth than the diameter of the cable or conductor is made, this pocket being tinned
to ensure union with the molten metal mentioned below. Preparatory to laying
the cable in the neck a part of the outer stranded wire covering of the cable is
removed so as to expose at the inner end of the neck a short length of the lead
coating of the cable. The projecting portion of the stranded outer coating of the
concentric cable which reaches into the pocket is tinned to ensure union with the
molten metal filling and the central conductor of the cable with its insulator passes
intact into the hollow central portion or body. The hollow central portion or body
of the junction box or case which is to contain the contact piece or other apparatus
is then filled with sand and molten metal having a lower melting point than that of
lead is poured into the pocket and allowed to overflow until the junction box or
case and the external conductor or sheathing of the cable are sufficiently heated to
ensure metallic union or the pocket may be filled until the metal is flush with the
upper surface of the casing and afterwards heated until union is effected as
described whereby a thoroughly water tight joint is produced. The sand is then
removed from the hollow central portion of the junction box or case the apparatus
to be contained is fitted in and connected to the central conductor from the top and
backed up and supported by a disc of insulating material. The hollow central
portion is then covered over and sealed with a metallic plate soldered or otherwise
secured water tight to the metallic body.
Under another mode of making the joint, a cup, which may be cast separately
and attached to the junction box or case after the molten metal is run into the
pocket is substituted for the U shaped neck and pocket. The cup is open at one
end and with the exception of a hole of sufficient diameter to pass the insulated
central conducting wire or wires of the cable closed at the other end. Previous to

page_text: inserting the cable through the open end of this cup which is wider than the
diameter of the cable the stranded protecting covering is so removed that whilst it
extends for a distance into the cup it does not reach the closed end but exposes a
length of the lead covering. The end of the stranded conductor and inside of the
cup are tinned as described. Molten metal is poured into the cup from the open
end to fill the annular space and allowed to overflow or afterwards heated as
described for the pocket so making a joint which is water tight.
The invention is also applicable to making direct connection with fittings or
lampholders switches and like apparatus and also making connections to cables
which are not provided with a lead covering under the external sheathing or other
covering which may or may not form a return conductor or to lead sheathed wires
whether the sheathing forms the return conductor or not.
Dated this Fifth day of October 1891.
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.
COMPLETE SPECIFICATION.
Improvements in or relating to Metallic Junction Boxes or Cases
for Conductors or Fittings for Electric Lighting, Electric Bell
Circuits, and like purposes, and in the Mode of Connecting the
Conductors thereto.
We, HENRY ALEXANDER MAVOR, WILLIAM ARTHUR COULSON and
SAM MAVOR of the firm of Mavor and Coulson, Electrical Engineers and
WILLIAM BROOKS SAYERS, Electrical Engineer, all of 56 George Square,
Glasgow, in the County of Lanark, 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 :-
This invention which relates to metallic junction boxes or cases for concentric
and other conductors or fittings for electric lighting electric bell circuits and like
purposes and to the mode of connecting conductors thereto has for its object to
provide improved means of connecting the lead or other external sheathing or
Sheathings of the conductors to the junction boxes or cases and whereby any risk of
damp or moisture seeking or searching back from the junction box or case along
the insulating coating of the central conductor in either direction is obviated whilst
at the same time the improved construction greatly facilitates the making of the
connection and the insertion of apparatus within the junction box or case.
с
Under one form of the invention which is illustrated in part vertical section and
part elevation at Figure 1 in part plan and part horizontal section on the line A-B
at Figure 2 and in transverse section on the line C-D at Figure 3 of the
accompanying drawings, the junction box or case a is at each end where the
conductors are led in and out formed with a projecting neck or support c which is
U shaped in cross section. Into these necks c the cables or conductors 6 are laid
and between the end of the neck and the hollow central portion or body of the
junction box or case a pocket or part d of greater width and depth than the
diameter of the cable or conductor 6 is made, this pocket being tinned to ensure
union with the molten metal hereinafter referred to. Preparatory to laying the
cable in the neck a part of the outer stranded wire covering of the cable is
removed so as to expose at the inner end of the neck a short length of the lead
coating of the cable. The portion of the stranded outer covering of the
concentric cable which reaches into the pocket is tinned and the short length ƒ of
exposed lead coating is cleaped and, treated with flux or it may also be tinned to
easure unison of both lead and outer covering with the metal filling g. The central
-conductor of the cable with its insulating covering i and preferably also the end
of the exposed part of the lead covering passes intact into the hollow central

page_text: portion or body a of the junction box or case which is to contain the contact piece j
or other apparatus and the hollow is then filled with sand and molten metal having
a lower melting point than that of lead is poured into the pocket d and neck c and
allowed to overflow until the junction box or case and the external conductor or
sheathing of the cable are sufficiently heated to ensure metallic union or the
pocket may be filled until the metal is flush with the upper surface of the casing
and afterwards heated until union is effected as described whereby a thoroughly
water tight joint is produced. The filling is or may be composed of fifty (50) per
centum of tin and fifty (50) per centum of lead. The sand is then removed from the
hollow central portion of the junction box or case the apparatus to be contained is
fitted in and connected to the central conductor h and backed up and supported by
a disc or diaphragm k of insulating material and the hollow central portion is then
covered over and sealed with a metallic plate / soldered or otherwise secured water
tight to the metallic body a.
Figure 4 is a separate plan and Figure 5 a part elevation of the metal cover plate
with the insulating disc k.
In Figure 1 the through way of the junction box has a pendant shewn connected
to it and the invention also embraces a form of joint suitable for this and other
purposes and which consists of a cup m cast or made separately from the junction
box a and screwed thereinto or otherwise fastened in position after the molten metal
has been run into the pockets d. The -cup m is open at one end and with the
exception of a hole of sufficient diameter to pass the insulated central conducting
wire or cable through closed at the other end either by the insertion of a filling
plug or neck as at n or by so forming the end of the cup itself. Previous to
inserting the cable through the open end of the cup and which is wider than the
diameter of the cable the stranded protecting covering b¹ is so removed that whilst
it extends for a distance into the cup it does not reach the closed end or part n but
exposes a length of the lead covering f. The end of the stranded protecting
covering and the inside of the cup m are tinned and the exposed portion of the
lead covering is cleaned and treated with flux or it is also tinned to ensure unison
with the filling g as before described. Molten metal is then poured into the cup
from the open end to fill it and allowed to overflow or the cup is afterwards heated
until union is effected so making a joint which is water tight.
The lower end of the pendant cable is also shewn with a like cup joint for
coupling it to a lamp holder or other fitting and Figure 6 shews partly in section
and partly in elevation a thimble end on the cable in conjunction with the cup joint
for connecting with a box.
The invention is also applicable to making direct connections with switches and
like apparatus and also to making connections to cables which are not provided
with a lead covering under the external sheathing which sheathing may or may not
constitute a return conductor. And to lead covered wires whether there is or is
not a stranded protecting sheathing and whether the said sheathing forms the
return conductor or not and also to cables which have an insulating covering of
any kind either with or without an outer metallic covering.
Figures 7, 8, 9 and 10 shew in plan and elevation respectively various forms of
the improved junction box Figure 7 being views of a butt- junction box, Figure 8
views of a four way junction box, Figure 9 views of a "blind" three way junction
box and Figure 10 views of a box having an oblong as distinguished from a circular
central cavity. It is to be understood that we do not confine ourselves to these
forms. Figure 11 shews in plan and elevation contact discs j for junction of central
conductors in through way junction boxes illustrated by Figures 1, 2 and 3 or
contact for fitting in butt junction box such as is illustrated by Figure 7.
Figure 12 shews similar views of contact disc for a three way junction box such as
is illustrated by Figure 9. Figure 13 shews similar views of contact disc for four
way junction box such as is illustrated at Figure 8 and Figure 14 shews similar
views of junction box for central conductor in large cables,

page_text: Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. A metallic junction box for electrical conductors having a central cavity a to
contain a part or parts to be used as contacts or otherwise said cavity being closed
by a water tight covering, one or more pockets projecting outwards from the wall
of said cavity and each having a neck into and through which the conductors are
laid the lead or other external sheathings of the conductor being sealed water tight
to the interior of the necks and pockets by molten metal substantially as described
with reference to the drawings annexed.
2. A metallic junction box for electrical conductors consisting of a cup having at
one end an opening wider than the diameter of the cable and at the other end an
opening sufficient only to pass the insulated central conductor of the cable the
metallic sheathings of the cable being sealed water tight to the interior of the cup
by molten metal substantially as described with reference to the appended
drawings.
3. A metallic junction box or case constructed substantially as described with
reference to Figures 1, 2 and 3 of the annexed drawings and wherein provision is
made for passing a conductor through the box without dividing or breaking, the
portions of the conductor at the entrance and exit being sealed water tight to the
box by molten metal as set forth.
4. The method of joining or sealing water tight the metallic coverings of an
electrical conductor to a metallic junction box substantially as hereinbefore
described with reference to the annexed drawings.
Dated this Twenty-ninth day of January 1892.
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.