Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Plug-in Electrical Accessories
The Description
Technical Field
The invention is a new type of electrical wiring accessory that provides early
completion of
the wiring within a building to allow full testing of the system by using a
plug-in accessory.
It also provides an adaptability that permits easy interchangability of
outlets to suit differing
national standards and outlet ypes.
Background Art
The problem in the installation of electrical accessories in buildings has
always been that
conduits and cables are installed early in the construction programme and then
tested and
connected to the accessory at the end.
Should a failure of a cable occur. it will not be discovered until much later
when it can often
be difficult to access the conduit with all the other services and
architectural finishes in place.
The replacement of cables is generally quite time consuming.
With the systems in use at present. the cables once installed are left loose
or wound up in the
I S accessory box where they are subject to damage. The accessory box is often
filled with
cement or plaster as the wall finishes are applied.
In order to test and commission the wiring system the cables have to be
terminated which
means the accessories and luminaires have to be installed. This makes the
testing of the
complete lighting circuit very difficult; either the lamps are removed or, in
the case of
fluorescent luminaires, the lamp circuits are disconnected or, as normally
happens the light
switches are in the "off' position. With the light switches off. the phase
conductors to the
luminaires, i.e. the switch lines, are not tested!
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Due to the testing and commissioning of the wiring system, the accessories
themselves are
normally installed before the final painting of walls. This often leads to the
accessory being
'painted' along with the walls, sometimes requiring the accessory to be
replaced or at the
very least needing extensive cleaning. Some contractors try to cover the
accessory with a
tape to avoid the paint damage, but this is time consuming and not very
successful.
Once the building is in use. it will in time need repainting, and then the
problem arises again.
With the growing diversiy of building tenant / owner nationalities in all
countries there is
sometimes a desire to have different accessory types (American, British,
German, ......
pattern of accessory). Changing the accessory type on the existing systems is
not easy, and
will generally need an electrician to carry out the work.
The plug-in electrical accessory (the Invention) has been developed to
overcome these
problems.
Disclosure of Invention
The invention is an accessory box with a plug-in accessory plate for use on a
conventional
conduit system that overcomes all the problems noted in the background to the
Invention and
noted below.
This device is a complete suite of electrical accessories that allows the
wiring system within a
building to be fully wired, connected and tested at an early stage in the
construction.
As stated earlier, in order to test and commission the wiring system the
cables have to be
terminated which means the accessories and luminaires have to be installed.
This requires
either the lamps to be removed or, in the case of fluorescent luminaires, the
lamp circuits to
be disconnected. What normally happens is the light switches are in put in the
''off' position
which means the phase conductors to the luminaires, i.e. the switch lines, are
not tested. This
can sometimes be a considerable percentage of the circuit wiring. The
invention overcomes
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this by allowing all the circuit conductors to be installed and terminated
without connecting
the luminaires or the accessories, thus full testing can be carried out.
All the finishes can be applied to the building and then the accessories
plugged in, thus
avoiding damage to the accessory by the finishes and visa versa.
The accessory comprises three basic parts
a) the accessory box (Fig 3)which is installed with the conventional conduit
system
b) the accessory itself (Fig 6) which is a socket/outlet/receptacle, lighting
switch, etc.
c) a temporary cover plate (Fig 8) which can be replaced with a maintenance
cover plate.
The accessory box provides permanent termination of the wiring with plug-in
facilities for
the accessory.
The accessory, which could be socket outlet, lighting switch, ceiling rose, or
whatever, plugs
into the accessory box providing connection to the external circuit. Upon
completion of the
room finishes, the accessory is simply plugged into the accessory box and is
ready for use
without any further installation required.
I S If it is necessary to redecorate the room, it is a simple matter to unplug
the accessory, fit the
temporary cover plate, decorate, remove the cover plate and then plug the
accessory back in.
It does not need an electrician.
If the decorating is to be done at night or the room has no windows then a
maintenance cover
plate (a plug-in lighting switch bypass) can be installed. This would be
similar to the
temporary cover plate and would inter-connect the wiring to keep the lighting
on for as long
as the device is in place. With 2-way and intermediate switching, removing one
of the 2-way
or intermediate switches would not affect the operation of the other, so there
would be no
need to by-pass the switch.
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If for any reason the accessory type, i.e. American pattern accessories, are
required to be
changed for say German pattern, it is only necessary to unplug one device and
replace it with
the other.
The accessory range would cover all devices required within a building and
would fully
comply with national and international standards.
All devices would be rated at 250V to allow for any national voltage.
The Accessor~Box (Fig 3)
The accessory box is a moulded plastic box ( 1 ) arranged to connect to a
standard conduit
system (2) using a male bushing into a conduit coupler (3).
The external sides of the box are flanged (4) to link another accessory box
onto any of the
four sides. This allows accessory boxes to be joined together to form mufti-
ganged
arrangements up to any number in a matrix form. The flanges ensure that the
alignment and
spacing of a group of accessories is accurate and consistent. Fig. 5 shows
typical elevations
of the accessory box.
These same flanges are used to provide fixation when the boxes are recessed
into a block or
concrete wall. They also act as 'wings' behind plasterboard in a dry partition
to prevent the
box pulling through. The box would have fixing holes (5) in the base, set to
allow for minor
re-alignment.
Conduit entries are provided on each side; two on the top and bottom side (6)
and one on the
other two sides (7). Each box when joined to others, can interconnect to it's
adjacent box
through the conduit entry holes or they can be blanked off as necessary. This
allows wiring
devices of different voltage grades to be installed adjacent to each other and
maintain
segregation of the wiring as required by the national and international
regulations.
Inside and on each side of the box are the cable connection terminals (8).
There are twelve
terminals for low current devices rated at 10 amps and below such as light
switches and
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controls and eight terminals for power outlets (and higher rated light
switches) rated up to 20
amps. The terminal could be a barrel screw terminal as shown or any other
type.
Each of the terminals are connected to a live rail (9) which is encapsulated
in a slot ( 10) that
takes the leg of the accessory.
The accessory when inserted in the slot (10) will connect it (Fig 6) to the
cable system by the
live rail (12) in the accessory being in pressure contact with the live rail
(9) in the accessory
box. Fig. 7 shows the detail of the live rail connection between the accessory
and the
accessory box.
The fixing of the accessory to the accessory box is by sliding the legs (18)
of the accessory
into the live rail slots ( 10) of the box. When the accessory is pushed down
on to the top of the
box, a fixing clip (I l) will hold the accessory in place. The accessory is
removed by lifting
the edge of the accessory with the flat blade of a screwdriver in the slot
provided and
disengaging it from the fixing clip.
The Accessory (Fig 6)
The arrangement shown in Fig 6 describes a typical socket outlet/receptacle
for a British
system. Variations on this would be used for the other types of outlet and
also for direct cable
connection to luminaires and appliances, etc.
The accessory comprises two main parts; the wiring device (13) and the cover
plate ( 14). The
wiring device would be a standard design for each type of accessory. The cover
plate, made
of either plastic or metal, would be stylised to suit the architectural design
and finish of the
accessory and would be factory fixed to the wiring device.
As a socket outlet, as shown in the drawings, the wiring device (13) is a
plastic assembly
incorporating a recess ( I S) for the spring clip ( 16) for the appliance plug
(24) to connect to;
and the live conductors (17) which become the live rail (12) which are
connected to the
accessory leg ( I 8). The back of the leg is angled ( I 9) to provide
additional support for the
live rail when under pressure from the contact with the live rail in the
accessory box.
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When the accessory is a switch or other such device that interconnects parts
of the fixed
building wiring system, the wiring device will interconnect the appropriate
live rails in the
legs to make the necessary interconnections.
The two live rails are arranged to have a slight interference fit when the
accessory is inserted
into the accessory box. Pressure is maintained, to ensure a positive contact
between the two,
by the inherent tension in the accessory leg due to the shape of the leg. The
leading edge of
the live rails (9 & 12) are shaped (21) to allow easy entry of the accessory
leg (18) into the
live rail slot ( 10) in the accessory box. The top section of the live rail is
encapsulated in
plastic (20) to prevent access to the accessory live rail (12) once the rail
is in contact with the
accessory box live rail (9). The earthing/grounding rail will be longer than
the live rails to
ensure positive earth connection before any live connections are made.
For a power outlet, the plug-in facility will provide connections allowing it
to be used for but
not limited to
a) a single phase socket outlet (live, neutral and earth), switched or
unswitched
b) a two phase socket outlet (live l,live 2, neutral and earth), switched or
unswitched
c) a three phase socket outlet (Red, Yellow and Blue phases, neutral and
earth),
switched or unswitched
d) a 20 amp double pole switch (live and neutral supply; live and neutral
load; and earth)
e) a fused connection unit (live and neutral supply; live and neutral load;
and earth),
switched or unswitched.
f) isolators and isolating switches up to 20 amp rating
The connections are always in the same location irrespective of the type of
accessory to
enable complete interchangability (provided the circuit connections are
available in the box).
For a lighting device, the plug-in facility will provide connections allowing
it to be used for
but not limited to
a) 1 way lighting switches
b) 2-way lighting switches
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c) Intermediate lighting switches
d) Lighting controls including dimmers and infra-red controls, etc.
e) Ceiling roses
f) Connection boxes to luminaires
g) Switch by-passes for maintenance purposes
The connections are always in the same location irrespective of the type of
accessory to
enable complete interchangability (provided the circuit connections are
available in the box).
For other devices, the plug-in facility can be provided in different
configurations, allowing it
to be used for a wide number of other connections including but not limited to
a) HVAC controls
b) Audio outlets
c) Telephone outlets
d) Data outlets
e) TV and Radio outlets
f) Clocks; both mains
and central
g) Others
The accessory incorporates the switch, socket outlet, etc. connected
internally to the plug-in
legs which mate with the accessory box. Once plugged in the device is
connected to the
supply.
The Temporary Cover Plate (Fig 8)
Although the Temporary Cover Plate does not form part of the invention the
description
hereunder is added for completeness of the system.
The temporary cover is a flat clip-on plastic cover that fits level with the
top of the accessory
box. This firstly protects the cabling inside and provides a surface level
with the surrounding
finishes to allow plastering and decoration to proceed without having the
accessory fitted.
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The temporary cover (22) is a flat plastic cover that fits into the recess at
the top of the
accessory box. This also has legs (23) to align with the live rail slots (10)
in the accessory
box. These do not carry a live rail.
The Maintenance Cover Plate Fig (8)
For maintenance purposes and redecoration, a maintenance cover plate, similar
to the
temporary cover plate, complete with live rails would be used as a lighting
switch bypass.
The live rails would be interconnected to simulate a closed switch.
Schedule of Element Numbers
1 Accessory Box 14 Cover plate
2 Conduit system 15 Spring clip recess
3 Conduit coupler 16 Spring clip
4 Accessory box flanges 17 Live conductors
5 Accessory box fixing holes 18 Accessory leg
6 Conduit entry hole 19 Angled support for
the leg
7 Conduit entry hole 20 Encapsulation of accessory
leg
8 Cable connection terminals 21 Shaped end of live
rails
9 Accessory box live rail 22 Temporary Cover
Live rail slot 23 Legs of temporary
Cover
11 Accessory fixing clip on the 24 13 Amp plug
accessory box
12 Accessory live rail 25 Wall
13 Wiring device 26 Plaster
Brief Description of Drawings
The drawings have been produced to show the principle elements of the
invention, sufficient
10 to enable a manufacturer to develop the system to a production product. The
system covers a
large variation in types of electrical accessories, therefore, the drawings
have only been
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produced to show one type. The principles of the invention do, however, apply
equally to the
other variations.
Fig 1 shows the general arrangement of the invention with the two principle
parts, viz. the
accessory box and the accessory. The elevation indicates how the parts,
including a
plug, would fit together.
Fig 2 shows a section of the complete assembly
Fig 3 shows the detail of the accessory box based upon an accessory with a
rating above 10
Amps, such as a socket outlet/receptacle.
Fig 4 shows a section through the accessory box to show the arrangements for
the 4 no. 20
Amp terminals.
Fig 5 provides elevations of the accessory box indicating the arrangement of
the flanges and
the conduit entries.
Fig 6 describes the accessory in detail based upon a British style l3Amp
socket
outlet/receptacle.
Fig 7 shows the detail of the live rail.
Fig 8 shows the temporary cover plate. The maintenance cover plate is similar.
Best Mode for Carrvin~ Out the Invention
The existing methods of plastic injection moulding and production of
electrical wiring
accessories would apply to the production of this invention.
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Industrial Applicability
The domestic accessory market with the inventions adaptability for
redecoration. Due to it's
plug in facility it would also be easy to change the accessory to suit a
change in interior
decoration style or colour.
5 The commercial market where there is a need to have the facility to
interchange the
accessories to have more than one nationaliy type of socket outlet to suit
different equipment
with moulded plugs.
The contractor market where
a) the ability to install the accessory box, terminate the wiring and test the
cables at a
10 very early stage in the installation would be a tremendous advantage.
b) installing the accessory plates at the end of the project, when time is
always
critical, takes a matter of seconds per unit instead of 15-30 minutes for a
conventional accessory.
c) the accessory itself need not be installed until after the final decoration
and
perhaps not until immediately before hand-over of the building. This avoids
damage to the accessory and reduces pilferage.
d) changes made by the client during construction to the style and type of
accessory
required becomes only a problem of procurement - not installation.
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Plug-in Electrical Accessories
The Drawings
The following drawings describe, together with the foregoing text, the detail
of the invention.
Fig 1 The General Arrangement of the Invention.
Fig 2 Section of the Complete
Assembly
Fig 3 The Detail of the Accessory
Box.
Fig 4 Section through the Accessory.
Fig 5 Elevations of the Accessory
Box.
Fig 6 The Accessory.
Fig 7 Detail of the Live Rail.
Fig 8 The Temporary Cover Plate.
SUBSTITUTE SHEET (RULE 26)
