Improvements in Plug Switches or Couplings for Electric Circuits.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in Plug Switches or Couplings for Electric Circuits.
We, THOMAS HERBERT MARSH and ALBERT VANDAM, trading as A. Vandam
& Co., of 39, Victoria Street, in the City of Westminster, Electrical Engineers, do
hereby declare the nature of this invention to be as follows:-
This invention has for its object to provide a plug switch for electric circuits in
which danger of short circuiting, or arcing, is obviated.
In a plug switch constructed according to this invention the base plate or
rose of the switch which is secured to the wall, or other place, has secured at, or
about its centre, a tubular piece, and partly surrounding this with a space
between is a partial tubular piece both pieces being made of non-conducting
material. One terminal consists of a metal tube projecting upwards in the
tubular piece, and connected by a metallic connection in a recess in the base
plate, to the binding screw, or other attachment, by which one of the line wires
is connected to the switch.
The aforesaid partial tubular piece partially surrounds the said tubular part
at a distance sufficient to receive a ring shaped piece of metal constituting the
other terminal and provided with a foot piece which is secured to the base plate,
and which carries the other binding screw, or other attachment, by which the other
line wire is connected to the switch. The said ring of metal is preferably slit so
that it acts as a spring-ring. The plug by which the circuit through the switch
is completed consists of a holder of non-conducting material carrying a central
metal stem preferably split to cause it to act as a spring stem) and surrounding it
a metallic tube, these two being metallically connected by wires passing to a
lamp, or the like, or by metal passing from one to the other through the plug.
The said stem and tube are so situated that when the plug is inserted in place in
the other part of the switch the metal stem of the plug enters the metal tube of
the other part or base plate and the metal tube on the plug bears against the
inner side of the spring metal ring carried, by the base plate, the non-conducting
tubular piece on the base plate entering the space between the metal stem and
the tube on the plug portion of the switch. The partial tubular piece of non-
conducting material on the base plate affords an efficient separation of the two
leading-in wires. The tubular non-conducting portion on the base plate prefer-
ably projects somewhat beyond the metal spring ring which surrounds it.
Dated this 3rd day of August 1897
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.

page_text: Improvements in Plug Switches or Couplings for Electric Circuits.
We, THOMAS HERBERT MARSH and ALBERT VANDAM, trading as A. Vandam
& Co., of 39, Victoria Street, in the City of Westminster, Electrical Engineers, 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 has for its object to provide a plug switch for electric circuits in
which danger of short circuiting, or arcing, is obviated.
We will describe our invention referring to the accompanying drawings in
which Figure 1 shews a plug switch in section, Figure 1A is a plan view of the
top thereof, Figure 2 is a plan with the plug and cover removed, and Figure 3
is a detached perspective view shewing the means employed according to this
invention for preventing short circuiting.
In a plug switch constructed according to this invention the base plate or
rose A of the switch constituting the socket which is secured to the wall, or other
place, has secured at, or about, its centre, a tubular piece 61 and partly sur-
rounding this, with a space between, is a partial tubular piece 6ª both pieces being
preferably formed in one with a base 63 as shewn clearly in Figure 3 and made of
non-conducting material. One terminal consists of a metal tube a¹ projecting
upwards in the tubular piece 61 and connected, by a metallic connection a³ in a
recess in the base plate A, to the binding screw a³, or other attachment, by which
one of the line wires z is connected to the switch.
The aforesaid partial tubular piece 6 partially surrounds the said tubular
part 6 at a distance sufficient to receive a ring shaped piece of metal c con-
stituting the other terminal and provided with a foot piece c¹ which is secured to
the base-plate A and which carries the other binding screw, or other
attachment, by which the other line wire a¹ is connected to the switch. The said
ring of metal c is preferably slit as shewn in Figure 2 so that it acts as a spring-
ring. The whole is enclosed in a porcelain or the like cover B. The plug by
which the circuit through the switch is completed consists of a holder D of non-
conducting material carrying a central metal stem d¹ (preferably split to cause it
to act as a spring stem) and surrounding it a metallic tube d these two being
metallically connected by wires yy passing to a lamp or the like or by metal
passing from one to the other through the plug. The said stem d¹ and tube d
are so situated that when the plug is inserted in place in the socket part of the
switch as shewn in Figure 1 the metal stem of the plug enters the metal
tube a¹ of the socket or base plate and the metal tube on the plug bears against
the inner side of the spring metal ring c carried by the base plate the non-
conducting tubular piece 61 on the base entering the space between the metal
stem and the tube on the plug portion of the switch. The partial tubular
piece 68 of non-conducting material on the base plate with connecting base b³
affords an efficient separation of the two leading-in wires and prevents any
accidental short circuiting at the base which otherwise might occur by the inser-
tion of a piece of conducting material such as wire or the like between either the
tube 6 or the partial tube 62 and the outer contact ring c. The inner non-
conducting tube 61 on the base plate preferably projects somewhat beyond the
metal spring ring c which surrounds it. In the plug e and el are binding screws
for the wires y y¹, and f is the usual insulating or dividing wall. We preferably
lead the wires yy in through a clamping device formed of a conical block g as
shewn in plan in Figure 1 which is divided through its vertical axis, each part

page_text: being formed with grooves g¹g which form 2 passages for the wires y y¹ when the
two parts of the block are placed together so that when the wires are passed
through the passages and the block is screwed up into the cover H of the plug
by the cap or clamping ring G the said wires are clamped in the passages and
the strain on the binding screws e and e¹ and the liability of the wires y y¹ to
become detached therefrom is removed. We lay no claim to the inner projecting
insulating tubular piece on the socket part as we are aware that such an
insulating piece has already been used in plug switches.
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. In plug switches of the kind described, the combination in the socket part,
of an inner tubular part and an outer partial tubular part both made of non-
conducting material and preferably formed in one piece with a non-conducting
base, substantially as and for the purposes described.
in
2. The combination of parts forming a plug switch for electric circuits, sub-
stantially as hereinbefore described and illustrated the accompanying
drawings.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.