Improvements in Fittings for Electric Lights.
Year: 1891

page_text: Date of Application, 16th Dec., 1891
Complete Specification Left, 10th Aug., 1892-Accepted, 10th Sept., 1892
PROVISIONAL SPECIFICATION.
Improvements in Fittings for Electric Lights.
1, JOHN SMALLWOOD of Cubitt Town, Poplar Middlesex Electrical Engineer
do hereby declare the nature of this invention to be as follows:-
This invention has for its object firstly to prevent any leakage of the electric
current and secondly to facilitate connecting and disconnecting electric light
fittings.
My invention consists in fitting any suitable block with a brass or other metal
insulator to prevent any leakage of the electric current. Such metal insulator is
fitted internally with one or more insulators of vulcanized fibre or other suitable
material whereon are mounted a suitable double pole fuse and two contact blocks
which make contact with two other contact blocks mounted on an insulating disc
attached to the stem of the fitting. This insulating disc is provided with a
suitable bridge piece to prevent short circuits and such bridge piece serves as a
guide block to bring the contact blocks into position. The electric wires are
connected to the contact blocks in any ordinary and convenient manner.
metal insulator is threaded externally and fitted with a screw cap which is mounted
on the stem and is kept in position by a check nut. When the fitting is put
together the metal cap is screwed over the metal insulator and secured by such
check nut thus fixing the contact blocks in position. When it is desired to
remove the fitting it is only necessary to unscrew such check nut and metal cap
when the contact is broken and the fitting can at once be removed.
The
By my invention I avoid the necessity of cutting the wires as heretofore, thus
effecting a considerable economy in time, labour, and expense, and greatly
facilitating the fixing and removal of the fittings.
Dated this 16th day of December 1891
ELT & Co.,
33, Southampton Buildings, Holborn, London, Agents for Applicant.
COMPLETE SPECIFICATION.
Improvements in Fittings for Electric Lights.
1, JOHN SMALLWOOD of Cubitt Town, Poplar, Middlesex, 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:
This invention more particularly relates to fittings for fixed electric lights and
has for its object firstly to facilitate connecting and disconnecting such fittings
and secondly to prevent any leakage of the electric current.
My invention consists of a metal fixing plate mounted on a suitable base block,
and furnished with a threaded rim over which a screw cap fits. Such metal
fixing plate prevents the absorption of damp and thus obviates any leakage of the
electric current. The screw cap is carried on the stem of the fitting which has a
threaded collar formed thereon, and is likewise fitted with a check nut that works
up and down thereon, and which when tightened up serves to secure the cap in
position. If desired such cap may be further secured by one or more set screws
passing through the rim of the cap into the rim of the fixing plate. The fixing
0

page_text: '
plate is fitted with an insulating block or blocks made of vulcanised fibre or other
suitable material and with a double pole fuse and two or more contact blocks.
By employing a double pole fuse instead of a single pole fuse as ordinarily used
I obtain additional safety, and thus minimise the risk of overheating and
consequent ignition If desired however such double pole fuse may be dispensed
with. The contact blocks on the fixing plate make contact with two or more
contact blocks mounted on an insulating disc attached to the threaded collar on
the stem of the fitting, or it may be attached to such stem in any other convenient
manner. The object of increasing the number of the contact blocks is to facilitate
dividing the electric current into several circuits, as for instance in a fifteen light
fitting, where the current could be divided into, say, three circuits. The insulating
disc carries a bridge piece made of any suitable insulating material that serves
to prevent short circuits and which fits into a groove formed in or left between
the insulating block or blocks mounted on the fixing plate. Preferably I recess
such groove out of the insulating block leaving a sufficient substance to cover 'hat
portion of the surface of the metal fixing plate which is immediately beneath such
groove. When the bridge piece is fitted in such groove it forms a guide block to
bring the contact blocks into position. The base block and fixing plate are both
perforated to allow of the conducting wires being passed through and connected to
the contact blocks in any convenient manner.
I would here observe that the arrangement hereinbefore described may be
reversed, that is to say, the bridge piece may be mounted on the insulating block
on the fixing plate, and the groove formed in the insulating disc fitted to the stem
of the fitting. In either arrangement however the operation of my invention is
the same.
This reversed arrangement is not illustrated in the accompanying
drawings as it is sufficiently obvious in itself, and will be readily understood by
any practical maker of electric light fittings.
DRAWINGS.
In the accompanying drawings, (wherein similar letters of reference indicate
corresponding parts,) Figures 1 and shew plan views of the fixing plate and
insulating disc Figure 3 shews a section of the fixing plate taken on the line 1. 1.
Figure 1, and a side elevation of the stem of the fitting with threaded collar,
screw cap, and check nut thercon. Figure 4 is a plan shewing the bridge piece
fitted into the groove or recess and the contact blocks in position, and Figure 5
shews a view in side elevation of such stem as it appears when fitted to the fixing
plate complete a is the fixing plate mounted on a base block ab the threaded
rim of the fixing plate-c the screw cap on stem which fits over such threaded
rim-- the check nut for securing such screw cap in position-e the threaded collar
on stem insulating block mounted on fixing plate with groove f1 formed
therein g contact blocks mounted on such insulator or insulators- insulating
disc attached to threaded collar on stem of fitting, and furnished with bridge
piece that fits into the groove f¹ in or between the insulator or insulators, in
the manner above described-i contact blocks mounted on such insulating disc,
which make contact with the contact blocks g when the bridge piece is fitted into
the groovej double pole fuse mounted on the fixing plate a-k conducting wires
whereby the electric current is conveyed to the contact blocks.
When the fitting is put together the screw cap c is screwed down over the
threaded rim b, and secured by. the check nut d, thus fixing the contact blocks in
position, and when it is desired to remove the fitting, it is only necessary to
unscrew such check nut and cap, when the contact is broken and the fitting can at
once be removed. By my invention I avoid the necessity of cutting the wires in
order to remove the fitting, thus effecting a considerable economy in time, labour,
and expense, and greatly facilitating the operation of fixing and unfixing the
fitting. I also avoid the inconvenience attending the slack wire which has hitherto
been indispensable but which I am enabled to dispense with by my improved
method of connecting the fitting as above described.

page_text: 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. In a fixed electric light fitting, the combination of an insulating disc and
bridge piece furnished with any convenient number of contact blocks, and carried
on the stem of the fitting, with a grooved or recessed insulating block or block's
furnished with any convenient number of contact blocks, and either fitted or not
with a double pole fuse, and mounted on a metal fixing plate provided with a
suitable cap, all substantially as hereinbefore described and shewn.
2. In a fixed electric light fitting, the combination of a grooved insulating disc
furnished with any convenient number of contact blocks and carried on the stem of
the fitting, with an insulating block furnished with a bridge piece and with any
convenient number of contact blocks, and either with or without a double pole
fuse, and mounted on a metal fixing plate provided with a suitable cap, all sub-
stantially as hereinbefore described.
Dated this 10th day of August 1892
JOHN SMALLWOOD.