Field of the Invention

The present invention relates to a wiring device.

Background of the Invention

Conventionally, devices such as radios or telephones make use of a direct current source as their driving current source. There are widely known direct current outlets for supplying a direct current to such direct current devices (see, e.g., Japanese Patent Laid-open Publication No. 7- 15835, paragraphs 0021-0023 and Fig. 1) . The direct current outlet disclosed in Japanese Patent Laid-open Publication No. 7-15835 includes a direct current socket corresponding to a pin-type plug of an AC adaptor. The direct current outlet lacks versatility because the shape of a plug differs from maker to maker and from country to country.

As a connector used in a direct current or alternating current low-voltage circuit, plugs and sockets for a safety extra low voltage (SELV) circuit are specified in IEC Standards (CEI/IEC 906-3) . Conventionally, there exists no wiring instrument provided with a socket complying with IEC Standards and capable of being mounted in a embedded state through the use of a flush-mount box standardized in different countries.

Summary of the Invention

In view of the above, the present invention provides a wiring device provided with a socket complying with IEC Standards and capable of being mounted in a embedded state through the use of a standardized flush-mount box. In accordance with a first embodiment of the invention, there is provided a wiring device including: a socket body having a receptacle portion provided on a front surface thereof so that a plug of a power supply cord extending from a load device is removably coupled to the receptacle portion, the receptacle portion complying with IEC Standards, the plug having voltage electrode pin terminals; and a frame member to which the socket body is attached, the frame member being fixed to a flush-mount box with a rear portion of the socket body accommodated within the flush-mount box, the flush-mount box being standardized for flush-mount wiring purposes and being embedded in a wall surface, wherein the receptacle portion includes: a plug insertion hole into which the plug is inserted; a cylindrical columnar protrusion portion protruding forwards from a bottom surface of the plug insertion hole,- terminal insertion holes opened on a front surface of the protrusion portion so that the voltage electrode pin terminals of the plug are connected to the terminal insertion holes; and pin-receiving members for electrical connection with the voltage electrode pin terminals inserted inside the socket body through the terminal insertion holes, and wherein the frame member includes a mounting frame having an instrument- fitting window opening whose transverse dimension is greater than available in a mounting frame for large-square-boss-type interchangeable wiring instruments standardized in Japanese Industrial Standards, and the front surface of the socket body has a transverse dimension greater than available in the large-square-boss-type interchangeable wiring instruments standardized in Japanese Industrial Standards.

With such configuration, the socket body provided with the receptacle portion complying with IEC Standards is attached to the flush-mount box standardized for flush-mount wiring purposes, through the use of the frame member having the instrument- fitting window opening whose transverse dimension is greater than available in the mounting frame for large-square-boss-type interchangeable wiring instruments standardized in Japanese Industrial Standards. This makes it possible to mount the socket body in an embedded state using the standardized conventional flush- mount box . In accordance with a second embodiment of the invention, there is provided a wiring device including: a socket body having a receptacle portion provided on a front surface thereof so that a plug of a power supply cord extending from a load device is removably coupled to the receptacle portion, the receptacle portion complying with IEC Standards, the plug having voltage electrode pin terminals; and a frame member to which the socket body is attached, the frame member being fixed to a flush-mount box with a rear portion of the socket body accommodated within the flush-mount box, the flush-mount box being standardized for flush-mount wiring purposes and being embedded in a wall surface, wherein the receptacle portion includes: a plug insertion hole into which the plug is inserted; a cylindrical columnar protrusion portion protruding forwards from a bottom surface of the plug insertion hole; terminal insertion holes opened on a front surface of the protrusion portion so that the voltage electrode pin terminals of the plug are connected to the terminal insertion holes; and pin- receiving members for electrical connection with the voltage electrode pin terminals inserted inside the socket body through the terminal insertion holes, and wherein the socket body is formed to have a shape and size complying with NEMA Standards .

With such configuration, the socket body has a shape complying with NEMA Standards and the socket body provided with the receptacle portion complying with IEC Standards is attached to the flush-mount box standardized for flush-mount wiring purposes, through the use of the same frame member as the wiring instrument complying with NEMA Standards . This makes it possible to mount the socket body in an embedded state using the flush-mount box complying with NEMA Standards .

In accordance with a third embodiment of the invention, there is provided a wiring device including: a socket body having a receptacle portion provided on a front surface thereof so that a plug of a power supply cord extending from a load device is removably coupled to the receptacle portion, the receptacle portion complying with IEC Standards, the plug having voltage electrode pin terminals; and a frame member to which the socket body is attached, the frame member being fixed to a flush-mount box with a rear portion of the socket body accommodated within the flush-mount box, the flush-mount box being standardized for flush-mount wiring purposes and being embedded in a wall surface, wherein the receptacle portion includes: a plug insertion hole into which the plug is inserted; a cylindrical columnar protrusion portion protruding forwards from a bottom surface of the plug insertion hole; terminal insertion holes opened on a front surface of the protrusion portion so that the voltage electrode pin terminals of the plug are connected to the terminal insertion holes; and pin-receiving members for electrical connection with the voltage electrode pin terminals inserted inside the socket body through the terminal insertion holes, and wherein the frame member is formed to have such a shape and size as to allow the frame member to be attached to a flush-mount box selected from the group consisting of an A box, a BS box and a C box. With such configuration, the socket body provided with the receptacle portion complying with IEC Standards is attached to the flush-mount box selected from the group consisting of an A box, a BS box and a C box, through the use of the frame member. This makes it possible to mount the socket body in an embedded state using the standardized conventional flush-mount box.

In the wiring device, the frame member may be unified with the socket body.

With such configuration, it is possible to mount the socket body within the flush-mount box in an embedded state without having to use a frame member formed independently of the socket body, which assists in reducing the number of parts .

In the wiring device, the plug may have a signal- transmitting pin terminal and the socket body includes a signal terminal connection portion to which the signal- transmitting pin terminal of the plug is removably coupled, the signal terminal connection portion being provided in a different position than the protrusion portion. With such configuration, it is possible not only to supply an electric current but also to transmit a signal by coupling the plug extending from the load device to the receptacle portion.

In the wiring device, the plug may have a grounding electrode pin terminal and the socket body includes a grounding terminal connection portion to which the grounding electrode pin terminal of the plug is removably coupled, the grounding terminal connection portion being provided in a different position than the protrusion portion.

With such configuration, it is possible to electrically ground the load device by coupling the plug extending from the load device to the receptacle portion.

In the wiring device, the plug may have a signal- transmitting pin terminal and a grounding electrode pin terminal, and the socket body includes a signal terminal connection portion to which the signal-transmitting pin terminal of the plug is removably coupled and a grounding terminal connection portion to which the grounding electrode pin terminal of the plug is removably coupled, the signal terminal connection portion and the grounding terminal connection portion being provided in different positions than the protrusion portion.

With such configuration, it is possible to supply an electric current, to transmit a signal and to electrically ground the load device by coupling the plug extending from the load device to the receptacle portion. Brief Description of the Drawings

The objects and features of the present invention will become apparent from the following description of embodiments, given in conjunction with the accompanying drawings, in which:

Fig. IA is a front view showing a wiring device in accordance with a first embodiment, Fig. IB is a front view of the wiring device with a decoration plate removed, and Fig. 1C is a side section view of the wiring device with the decoration plate removed;

Fig. 2 is an exploded perspective view showing a socket that forms the wiring device,-

Figs. 3A through 3D are front, top, right side and bottom views showing the socket of the wiring device;

Fig. 4A shows the positions of coupling grooves formed in the socket of the wiring device in case of a direct current, and Fig. 4B illustrates the positions of coupling grooves formed in the socket of the wiring device in case of an alternating current;

Fig. 5A is a perspective view showing a plug connected to the wiring device, and Fig. 5B is a front view thereof;

Fig. 6A shows the positions of identification ribs formed in the plug connected to the wiring device in case of a direct current, and Fig. 6B illustrates the positions of identification ribs formed in the plug connected to the wiring device in case of an alternating current;

Fig. 7 is an exploded perspective view of a plate unit of the wiring device as seen from the front side;

Fig. 8 is an exploded perspective view of the plate unit of the wiring device as seen from the rear side;

Figs. 9A through 9F are front, left vertical section, right vertical section, rear, first horizontal section and second horizontal section views showing a plate frame employed in the plate unit of the wiring device,- Figs. 1OA, 1OB and 1OC are views for explaining the order of mounting the socket to the plate unit of the wiring device,-

Figs. HA and HB are plan views illustrating installation examples of the wiring device; Figs. 12A and 12B are plan views showing further examples of the socket of the wiring device,-

Figs. 13A through 13C are plan views showing still further examples of the socket of the wiring device,-

Figs . 14A and 14B are block diagrams showing the interior of the socket of the wiring device,-

Fig. 15A is a front view showing a wiring device in accordance with a second embodiment, Fig. 15B is a front view of the wiring device with a decoration plate removed, and Fig. 15C is a side section view of the wiring device with the decoration plate removed;

Fig. 16 is a perspective view showing major parts of a socket of the wiring device;

Figs. 17A and 17B are perspective views showing different plugs connected to the wiring device;

Figs. 18A and 18B are plan views showing further examples of the socket of the wiring device;

Figs. 19A through 19C are plan views showing still further examples of the socket of the wiring device;

Fig. 2OA is an enlarged view showing major parts of a receptacle portion of a wiring device in accordance with a third embodiment, and Fig. 2OB is a front view of a plug connected to the receptacle portion,-

Fig. 2IA is an enlarged view showing major parts of a receptacle portion in a modified example of the wiring device of the third embodiment, and Fig. 21B is a front view of a plug connected to the receptacle portion;

Fig. 22A is a front view showing a wiring device in accordance with a fourth embodiment with a socket mounted to a mounting frame, Fig. 22B is a side view of the wiring device, and Fig. 22C is a front view of the wiring device with a decoration plate fixed in place;

Fig. 23A is a front view showing a modified example of the wiring device of the fourth embodiment with a socket mounted to a mounting frame, Fig. 23B is a side view of the wiring device, and Fig. 23C is a front view of the wiring device with a decoration plate fixed in place;

Fig. 24A is a front view showing another modified example of the wiring device of the fourth embodiment with a socket mounted to a mounting frame, Fig. 24B is a side view of the wiring device, and Fig. 24C is a front view of the wiring device with a decoration plate fixed in place; Fig. 25A is a front view showing another modified example of the wiring device of the fourth embodiment with a socket mounted to a mounting frame, Fig. 25B is a side view of the wiring device, and Fig. 25C is a front view of the wiring device with a decoration plate fixed in place; Figs. 26A through 26D are front views of sockets of a wiring device in accordance with a fifth embodiment, Figs. 26E through 26G are front views of mounting frames thereof, and Figs. 26H through 26K are front views of flush-mount boxes thereof; Figs. 27A and 27B are front and side views showing one of the sockets of the wiring device;

Figs. 28A and 28B are front and side section views showing one of the mounting frames of the wiring device;

Fig. 29 is a side section view showing the socket mounted to the mounting frame;

Figs. 3OA through 3OC are front views showing further examples of the socket of the wiring device;

Fig. 3IA is a front view showing a frame-unified socket and a decoration plate, Fig. 3IB is a front view of a plate-unified socket, and Fig. 31C is a front view of a flush-mount box; Fig. 32A is a front view showing a frame-unified socket and a decoration plate, Fig. 32B is a front view of a plate-unified socket, and Fig. 32C is a front view of a flush-mount box; Fig. 33A is a front view showing a frame-unified socket and a decoration plate, Fig. 33B is a front view of a plate-unified socket, and Fig. 33C is a front view of a flush-mount box; and

Fig. 34A is a front view showing a frame-unified socket and a decoration plate, Fig. 34B is a front view of a plate-unified socket, and Fig. 33C is a front view of a flush-mount box.

Detailed Description of the Preferred Embodiments

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First Embodiment)

A wiring device in accordance with a first embodiment of the present invention will be described with reference to

Figs . 1 through 14. The wiring device includes a socket A and a plate frame 110 (or a frame member) . The socket A includes a housing 1 (or a socket body) and a receptacle portion 20 complying with IEC Standards. The receptacle portion 20 is installed on the front surface of the housing

1. A plug 200 of a power supply cord extending from a load device is removably coupled to the receptacle portion 20. The housing 1 of the socket A is attached to the plate frame 110. The plate frame 110 is fixed to the front opening of a flush-mount box with the housing 1 of the socket A accommodated within the flush-mount box. The flush-mount box is embedded in the embedding pocket of a wall surface with the front opening thereof exposed to the outside.

As shown in Figs. 2 and 3, the housing 1 of the socket A includes a body 2 of rectangular hexahedral shape with an open front surface and a cover 3 of rectangular hexahedral shape with an open rear surface, both of which can be combined together to form the housing 1. The body 2 may be made of a thermosetting synthetic resin (e.g., an urea resin) superior in tracking resistance, and the cover 3 may be made of a synthetic resin (e.g., polybutylene terephthalate, i.e., PBT) showing elasticity and superior tracking resistance. In this connection, the housing 1 has a unit dimension which will be described below.

A pair of coupling claws 4 protrudes from each of the left and right end surfaces of the body 2, while a shoulder portion 5 protrudes from each of the left and right end surfaces of the cover 3. A coupling piece 6 extends from the rear edge of the shoulder portion 5 toward the body 2. The coupling piece 6 has a pair of engagement holes 6a engageable with the coupling claws 4 of the body 2 in a male-and-female relationship. When coupling the body 2 and the cover 3 together, the cover 3 is moved from the front side toward the body 2 so that the coupling claws 4 can be fitted to the engagement holes 6a of the coupling piece 6.

The internal space of the body 2 is bisected by a partition wall 7 formed in the longitudinal center portion of the body 2. The front end portion of the partition wall 7 protrudes forwards beyond the open surface of the body 2. Positioning juts 2a protruding forwards are formed in suitable positions of the circumferential wall of the body 2. When the body 2 and the cover 3 are coupled together, the partition wall 7 and the positioning juts 2a come into engagement with the recess portions (not shown) formed in the cover 3, thereby preventing looseness of the cover 3 relative to the body 2. A partition wall (not shown) is also formed inside the cover 3. If the body 2 and the cover 3 are coupled together, the partition wall 7 of the body 2 and the partition wall of the cover 3 make contact with each other, consequently dividing the internal space of the housing 1 into two independent compartments. Pin-receiving members 9 are arranged within the left and right compartments 8 of the body divided by the partition wall 7. Each of the pin-receiving members 9 includes a pair of mutually-opposing spring pieces 9a and a bracket-shaped connecting piece 9b interconnecting the spring pieces 9a in a single body. At the open ends of the connecting piece 9b, terminal pieces 9c are integrally formed with the connecting piece 9b in such a fashion as to protrude away from each other. The spring pieces 9a are inclined so that the gap between them becomes gradually narrower toward the upper side. The upper ends of the spring pieces 9a are inclined so that the gap between them grows gradually wider toward the upper side, thereby making it easy to insert the pin terminals 204a and 204b of the plug 200. A pair of locking springs 10 is arranged in each of the compartments 8 in an opposing relationship with the terminal pieces 9c of each of the pin-receiving members 9. Each of the locking springs 10 includes a contact piece 10a formed by bending one end of a band plate into an S-shape and a locking piece 10b formed by bending the other end of the band plate into a J-shape. Each of the locking springs 10 is accommodated within the body 2 in such a fashion that the contact piece 10a and the locking piece 10b are opposed to the corresponding one of the terminal pieces 9c.

In the rear wall of the body 2, there are formed wire insertion holes 2b through which electric wires are inserted between the locking springs 10 and the terminal pieces 9c. If the electric wires are passed through the wire insertion holes 2b and then inserted between locking springs 10 and the terminal pieces 9c at the side of the locking pieces 10b, they are gripped between the locking springs 10 and the terminal pieces 9c by the spring forces of the contact pieces 10a and the locking pieces 10b. Furthermore, the locking pieces 10b are cut into the electric wires. This makes it impossible to draw out the electric wires. Since wire connection can be performed by merely inserting the electric wires into the wire insertion holes 2b as noted above, the wire connection task is easy to perform as compared to a case where terminals with screws are used. In addition, two electric wires can be connected to each of the pin-receiving members 9 arranged within the compartments 8. Therefore, if one set of electric wires are used as power supply wires while the other set of electric wires are used as outgoing wires to be connected to another socket, it becomes easy to perform a wire connection task for connecting a plurality of sockets in parallel.

A release button 11 is arranged within each of the compartments 8 so that it can straddle the locking springs 10 opposed to the terminal pieces 9c of each of the pin- receiving members 9. The release button 11 makes contact with the locking pieces 10b of the locking springs 10 and is arranged to slide along the rear wall of the body 2. The positions in which the release button 11 makes contact with the locking pieces 10b are deviated from the positions in which the electric wires are gripped between the locking pieces 10b and the terminal pieces 9c. An operation hole 2c is formed in the rear wall of the body 2 in alignment with the release button 11. The locking piece 10b cut into each of the electric wires can be bent away from the corresponding electric wire by inserting the tip end portion of a minus screw driver into the operation hole 2c and pushing the release button 11. This makes it possible to draw out each of the electric wires. In this regard, it is typical that a solid wire with an insulating sheath is used as the electric wires . The stripping length of the insulating sheath is important in obtaining the required connection strength against the drawing-out force applied to the electric wires. In view of this, a groove- like gauge 2d indicating the length of a core wire to be exposed is provided on the rear surface of the housing 1. In the installation work, the insulating sheath is stripped to expose the core wire by a length corresponding to the gauge 2d. One receptacle portion 20 is formed in the front wall of the cover 3. The plug 200 is removably inserted into the receptacle portion 20. The shape, dimension and pole arrangement of the receptacle portion 20 and the plug 200 is in compliance with IEC Standards (CEI/IEC 906-3) . IEC Standards specify the shape, dimension and pole arrangement of the connectors used in eight SELV power sources (for an alternating current and a direct current of 6V, 12V, 24V and 48V) .

As shown in Figs. 5 and 6, the plug 200 is connected to the end portion of an electric cable 210 extending from a load device. The plug 200 includes a generally cylindrical grip portion 201 (or a plug body) and a cylindrical coupling portion 202 formed at the front end of the grip portion 201, the coupling portion 202 being smaller in diameter than the grip portion 201. A coupling hole 203 recessed in a circular shape is opened at the front end of the coupling portion 202. A reference rib 205 indicating a reference position protrudes from the inner circumferential surface of the coupling hole 203 and extends along the plug insertion- and-removal direction (namely, along the direction perpendicular to the paper plane in Fig. 5B) . Two pin terminals 204a and 204b of circular rod shape extending along the axis of the grip portion 201 are arranged on a straight line passing through the central axis of the grip portion 201 and orthogonal to the line segment linking the central axis of the grip portion 201 and the reference rib 205. The pin terminals 204a and 204b are symmetrical with respect to the central axis of the grip portion 201.

In case of the plug 200 for a direct current power supply, the pin terminal 204a positioned at the right side when the reference rib 205 lies at the upper side as shown in Fig. 6A serves as a positive electrode pin terminal and the pin terminal 204b positioned at the left side serves as a negative electrode pin terminal. An identification rib 206 for prevention of erroneous coupling protrudes from the inner circumferential surface of the coupling hole 203 and extends along the plug insertion-and-removal direction. The position of the identification rib 206 depends on the kinds of power supply (such as a direct current, an alternating current and a rated voltage) . Fig. 6A illustrates the position of the identification rib 206 formed in the plug 200 for a direct current power supply. In case where the power supply voltage is 6V, 12V, 24V or 48V in direct current, the identification rib 206 is formed in a 120°, 150°, 210° or 240° position spaced apart counterclockwise from the position of the reference rib 205 (or the 0° position) . Fig. 6B illustrates the position of the identification rib 206 formed in the plug 200 for an alternating current power supply. In case where the power supply voltage is 6V, 12V, 24V or 48V in alternating current, the identification rib 206 is formed in a 30°, 60°, 300° or 330° position spaced apart counterclockwise from the position of the reference rib 205. In this regard, the plug 200 shown in Fig. 5 is designed to work at DC 48V, in which plug the identification rib 206 is formed in a 240° position spaced apart counterclockwise from the position of the reference rib 205.

Referring again to Figs. 3B and 4, the receptacle portion 20 has a plug insertion hole 21 identical in shape and size with the front surface of the coupling portion 202 of the plug 200. The coupling portion 202 is removably inserted into the plug insertion hole 21. A cylindrical columnar protrusion portion 22 to be inserted into the coupling hole 203 of the plug 200 protrudes forwards from the bottom surface of the plug insertion hole 21. Terminal insertion holes 23a and 23b are opened on the front surface of the protrusion portion 22, the pin terminals 204a and 204b being respectively inserted into the terminal insertion holes 23a and 23b. The afore-mentioned pin-receiving members 9 are arranged inside the protrusion portion 22 in alignment with the terminal insertion holes 23a and 23b so that the pin-receiving members 9 can be electrically connected to the pin terminals 204a and 204b inserted through the terminal insertion holes 23a and 23b.

A coupling groove 24 indicating a reference position is formed on the outer circumferential surface of the protrusion portion 22 to extend along the plug insertion- and-removal direction. The terminal insertion holes 23a and 23b are arranged on a straight line passing through the central axis of the protrusion portion 22 and orthogonal to the line segment linking the central axis of the protrusion portion 22 and the coupling groove 24. The terminal insertion holes 23a and 23b are symmetrical with respect to the central axis of the protrusion portion 22. In case of the receptacle portion 20 for a direct current power supply, the terminal insertion hole 23a positioned at the left side when the coupling groove 24 lies at the upper side as shown in Fig. 4A corresponds to the positive electrode pin terminal and the terminal insertion hole 23b positioned at the right side corresponds to the negative electrode pin terminal .

An identification groove 25 for prevention of erroneous coupling is formed on the outer circumferential surface of the protrusion portion 22, the identification rib 206 of the plug 200 being fitted to the identification groove 25. The position of the identification groove 25 depends on the kinds of power supply (such as a direct current, an alternating current and a rated voltage) . Fig. 4A illustrates the position of the identification groove 25 formed in the receptacle portion 20 for a direct current power supply. In case where the power supply voltage is 6V, 12V, 24V or 48V in direct current, the identification groove 25 is formed in a 120°, 150°, 210° or 240° position spaced apart clockwise from the position of the coupling groove 24

(or the 0° position) . Fig. 4B illustrates the position of the identification groove 25 formed in the receptacle portion 20 for an alternating current power supply. In case where the power supply voltage is 6V, 12V, 24V or 48V in alternating current, the identification groove 25 is formed in a 30°, 60°, 300° or 330° position spaced apart clockwise from the position of the coupling groove 24. In this regard, the receptacle portion 20 shown in Figs. 1 through 3 is designed to work at DC 48V, in which the identification groove 25 is formed in a 240° position spaced apart clockwise from the position of the coupling groove 24. In the receptacle portion 20 set forth above, the identification groove 25 for engagement with the identification rib 206 of the plug 200 is formed on the outer circumferential surface of the protrusion portion 22 in a position that varies with the voltage supplied. This eliminates the possibility that the plug 200 differing in voltage is erroneously inserted into the receptacle portion 20, thereby making it possible to supply an electric current suitable for a load device . As the coupling portion 202 of the plug 200 suitable for the receptacle portion 20 is inserted into the plug insertion hole 21, the protrusion portion 22 comes into the coupling hole 203 of the coupling portion 202 while the reference rib 205 and the identification rib 206 formed on the inner circumferential surface of the coupling portion 202 are respectively slid into the coupling groove 24 and the identification groove 25 of the protrusion portion 22. At this time, the pin terminals 204a and 204b inserted beyond the protrusion portion 22 through the terminal insertion holes 23a and 23b of the protrusion portion 22 are electrically connected to the pin-receiving members 9. The plug 200 is kept connected to the receptacle portion 20 by the resilient contact force by which pin-receiving members 9 is resiliently pressed against the pin terminals 204a and 204b. Since the front surface of the protrusion portion 22 of the receptacle portion 20 is positioned rearwards of the front surface of the housing 1, it is possible to reduce the distance at which the plug 200 connected to the receptacle portion 20 protrudes from the front surface of the housing 1.

The housing 1 of the socket A is mounted to the plate unit 100 which will be described below. A pair of mounting claws 3a for engagement with the plate unit 100 protrudes from the shoulder portion 5 formed on each of the lateral surfaces of the cover 3. The front end portion of each of the mounting claws 3a is inclined so that the protruding distance of each of the mounting claws 3a from the shoulder portion 5 becomes gradually smaller toward the front side.

The plate unit 100 shown in Figs . 7 through 9 is used in arranging the socket A on a wall surface in an embedded state. The plate unit 100 includes a plate frame 110 for holding the housing 1 of the socket A in place and a decoration plate 120 for covering the plate frame 110 to provide a good-looking appearance. The plate frame 110 may be made of a synthetic resin or a metal. The plate frame 110 made of a synthetic resin exhibits an insulating property and has a vertically-elongated rectangular frame shape with a central rectangular window opening 111 through which the front surface of the housing 1 is exposed. The plate frame 110 includes a pair of frame pieces 113a and 113b and a pair of transverse pieces 112 and the left end portions (or the upper end portions in Fig. 9A) and the right end portions (or the lower end portions in Fig. 9A) of the frame pieces 113a and 113b are continuously and integrally interconnected by the transverse pieces 112. A fixed beam portion 114 and a movable beam portion 115, both of which have a band plate shape, are formed on the rear surfaces of the opposite longitudinal edges of the window opening 111 in a mutualIy-opposing relationship.

The movable beam portion 115 is continuously and integrally connected at its longitudinal ends to the frame piece 113b through connector portions 116 extending in the longitudinal direction of the movable beam portion 115. At two intermediate points, the movable beam portion 115 is continuously and integrally connected to the frame piece 113b through bridge portions 117 orthogonal to the movable beam portion 115. Slits 118a to 118c extending through the thickness of the plate frame 110 are formed between the connector portions 116 and the bridge portions 117 and between the bridge portions 117 themselves. The synthetic resin, of which the plate frame 110 is made, has flexibility, meaning that the movable beam portion 115 and the connector portions 116 are flexible. The lateral slits 118a and 118c are formed into an L-shape and the middle slit 118b is formed into a rectilinear shape. Slot- like openings 119 extending through the thickness of the plate frame 110 are formed in the areas of the frame piece 113b adjacent to the respective bridge portions 117 so that the portions of the plate frame 110 corresponding to the bridge portions 117 can serve as the movable beam portion 115.

Three pairs of retaining grooves 114a and 115a each engaging with the mounting claws 3a formed in pair on the opposite lateral surfaces of the housing 1 are arranged at an equal pitch on the surfaces of the fixed beam portion 114 and the movable beam portion 115 facing the window opening 111 (see Figs. 9B and 9C) . By bringing the mounting claws 3a of the housing 1 into engagement with the retaining grooves 114a and 115a, it is possible to attach the housing 1 to the plate frame 110 in such a fashion that the front surface of the housing 1 is exposed through the window opening 111. Abutment portions 114d and 115d abutting to the front surfaces of the shoulder portion 5 of the housing 1 are formed in the base portions of the fixed beam portion 114 and the movable beam portion 115 to keep the housing 1 from getting removed to the front side from the plate frame 110. In a nutshell, the housing 1 is attached to the plate frame 110 by bringing the front surfaces of the shoulder portion 5 into contact with the abutment portions 114d and 115d and allowing the rear surfaces of the mounting claws 3a to engage with the retaining grooves 114a and 115a.

In the tip end portions of the surfaces of the fixed beam portion 114 and the movable beam portion 115 facing the window opening 111, there are formed guide portions 114b and 115b having slant surfaces inclined so that the distance therebetween becomes gradually greater toward the tip ends. The guide portions 114b and 115b serve to guide the mounting claws 3a toward the retaining grooves 114a and 115a when the mounting claws 3a is introduced into the retaining grooves 114a and 115a at the rear side of the plate frame 110. More specifically, the housing 1 is mounted to the plate frame 110 in the manner as illustrated in Figs. 1OA through 1OC. The mounting claws 3a formed on one lateral surface of the housing 1 are brought into engagement with the retaining grooves 114a of the fixed beam portion 114. The housing 1 is pushed forwards relative to the plate frame 110 by aligning the front end portion of the housing 1 with the window opening 111. Then, the mounting claws 3a formed on the other lateral surface of the housing 1 are slid into the retaining grooves 115a under the guidance of the slant surfaces of the mounting claws 3a and the guide portion 115b, at which time the movable beam portion 115 is bent. In this manner, the mounting claws 3a can be brought into engagement with the retaining grooves 115a with ease.

In the base portion of the fixed beam portion 114, instrument removal holes 114c extending through the thickness of the plate frame 110 are formed between the respective pairs of retaining grooves 114a. The tip end portion of a screw driver or a removal-dedicated tool is inserted into one of the instrument removal holes 114c in a state that the housing 1 is attached to the plate frame 110. If the housing 1 is pressed toward the movable beam portion 115 with the tip end portion of the tool, the movable beam portion 115 is bent even by a weak force under the principle of leverage . This releases the engagement between the retaining grooves 114a of the fixed beam portion 114 and the mounting claws 3a of the housing 1, thereby making it possible to remove the housing 1 from the plate frame 110.

As stated above, the plate frame 110 has three pairs of retaining grooves 114a and 115a formed respectively in the fixed beam portion 114 and the movable beam portion 115, and the housing 1 has one pair of mounting claws 3a formed on each of the lateral surfaces thereof. This makes it possible to mount up to three housings 1 to the plate frame 110. In other words, the plate frame 110 is designed to hold three housings 1. The housing 1 whose dimension is set to allow up to three housings to be mounted to the plate frame 110 will be referred to as a single-module-dimension housing 1. By defining the relative mounting dimension of the housing 1 and the plate frame 110 in this manner, it becomes possible to mount an arbitrary number of, i.e., one to three, housing 1 to the plate frame 110. The pitch of the retaining grooves 114a and 115a formed in the fixed beam portion 114 and the movable beam portion 115 is equal to the pitch of the mounting claws 3a formed on each of the lateral surfaces of the single-module-dimension housing 1. Moreover, the retaining grooves 114a and 115a are arranged at an equal interval as set forth above. Therefore, the single-module- dimension housing 1 can be mounted to the plate frame 110 using two arbitrary retaining grooves 114a and 115a of the fixed beam portion 114 and the movable beam portion 115 positioned adjacent to each other. Fig. IB shows the housing 1 mounted to the plate frame 110.

Recess portions 131 are formed on the front surfaces of the intermediate portions of the transverse pieces 112 of the plate frame 110. Formed in each of the recess portions 131 are a box-fixing hole 132 through which to insert a box screw used in fixing the plate frame 110 to the flush-mount box (not shown) , screw insertion holes 133 through which to insert screws used in fixing the plate frame 110 to an installation surface such as a wall surface or the like, and scissor tool locking apertures 134 in which to lock a scissor tool (not shown) used in fixing the plate frame 110 to a wall panel or the like that forms an installation surface .

In the four corners of the plate frame 110, there are formed decoration plate locking holes 135 for locking the locking juts 123 protruding from the rear surface of the decoration plate 120. By inserting and locking the locking juts 123 in the locking holes 135, the decoration plate 120 can be removably attached to the plate frame 110 in such a fashion as to cover the front surface of the plate frame 110. The decoration plate 120 is made of a synthetic resin with an insulating property and is formed into a generally box- like shape. The decoration plate 120 includes a major portion 121 for covering the front surface of the plate frame 110, the major portion 121 having a rectangular shape when seen in a plan view, and a side wall 122 protruding rearwards from the peripheral edge of the major portion 121. The major portion 121 and the side wall 122 are continuously and integrally formed with each other. The locking juts 123 protrude from the four corners of the rear surface of the major portion 121. In the central area of the major portion 121, there is formed a window opening 121a through which to expose the front surface of housing 1 mounted to the plate frame 110.

Referring to Fig. 8, a slant surface 122a inclined so that the opening of the decoration plate 120 becomes gradually wider toward the tip end is formed on the inner surface of the side wall 122 of the decoration plate 120. Restraint ribs 124 for making contact with the side surface of the plate frame 110 to prevent misalignment of the decoration plate 120 with respect to the plate frame 110 are also arranged in plural number along the inner surface of the side wall 122 of the decoration plate 120.

As shown in Figs. 7, 9A and 9F, slant surfaces 113c gradually protruding outwards toward the rear side and extension portions 113d protruding outwards from the slant surfaces 113c are formed on the outer surfaces of the frame pieces 113a and 113b of the plate frame 110. Ribs 125 whose end surfaces make contact with the front surfaces of the extension portions 113d are formed to protrude from the inner surfaces of the longitudinal sidewalls 122 of the decoration plate 120. The ribs 125 serve to prevent the decoration plate 120 from becoming loose. When the decoration plate 120 is mounted to the plate frame 110, the restraint ribs 124 of the decoration plate 120 are guided along the slant surfaces 113c of the frame pieces 113a and 113b of the plate frame 110. This makes it easy to mount the decoration plate 120 to the plate frame 110.

A pair of cutout portions 126 is formed on one longitudinal side wall 122 of the decoration plate 120. If a force is applied in such a direction as to move the decoration plate 120 away from the plate frame 110 (namely, toward the front side) by inserting a tool (e.g., the tip end portion of a minus screw driver) into one of the cutout portions 126, the locking juts 123 of the decoration plate 120 are disengaged from the decoration plate locking holes 135. Thus the decoration plate 120 can be removed from the plate frame 110. Indentations 136 recessed inwardly from the slant surface 113c are formed in the frame piece 113b of the plate frame 110 in the positions corresponding to the cutout portions 126 of the decoration plate 120. The tool inserted into the cutout portions 126 can come into the indentations 136, which makes it easy to impart a force when removing the decoration plate 120. Ribs 137 smaller in thickness than the extension portion 113d extend from the rear end portions of the indentations 136 in such a length as not to protrude beyond the cutout portions 126 of the decoration plate 120. There is a fear that the installation surface may be damaged, if the tool is forcefully moved using the contact portion of the tool as a fulcrum point with the installation surface. Provision of the ribs 137 ensures that the tool inserted into the cutout portions 126 makes contact with the ribs 137. This makes it possible to prevent the installation surface from being damaged by the tool when the decoration plate 120 is removed from the plate frame 110.

On the rear surface of the decoration plate 120, there are formed protrusion pieces 128a to 128c along a line. The protrusion pieces 128a to 128c are respectively inserted into the three slits 118a to 118c formed in the plate frame 110, when the decoration plate 120 is mounted to the plate frame 110. The dimension of the protrusion pieces 128a to 128c is such that, when the protrusion pieces 128a to 128c are into the slits 118a to 118c, only a small gap is left between the inner circumferential surfaces of the slits 118a to 118c and the protrusion pieces 128a to 128c. More specifically, when the decoration plate 120 is mounted to the plate frame 110 carrying the housing 1, the three protrusion pieces 128a to 128c are inserted into the slits 118a to 118c while leaving only a small gap between the inner circumferential surfaces of the slits 118a to 118c and the protrusion pieces 128a to 128c. This restrains movement (or bending) of the movable beam portion 115 of the plate frame 110. As a result, even if an impact is applied by, e.g., drawing out the plug 200 from the socket A with an exceptionally great force, the movable beam portion 115 is restrained from movement. Therefore, the mounting claws 3a of the housing 1 are seldom disengaged from the retaining grooves 114a and 115a of fixed beam portion 114 and the movable beam portion 115, which makes it possible to prevent unwanted removal of the housing 1.

As described above, the wiring device of the present embodiment includes the socket A and the plate unit 100 (or a frame member) . The socket A includes the housing 1 and the receptacle portion 20 complying with IEC Standards. The receptacle portion 20 is installed on the front surface of the housing 1. The plug 200 for a direct current power supply is removably coupled to the receptacle portion 20. The housing 1 of the socket A is attached to the plate frame 110. The plate unit 100 is fixed to the front opening of the flush-mount box with the rear portion of the housing 1 accommodated within the flush-mount box. The flush-mount box is embedded in the embedding pocket of the wall surface with the front opening thereof exposed to the outside. The socket A can be mounted in an embedded state using the plate unit 100. It is also possible to mount the socket A to the plate unit 100 together with other wiring instruments. For example, as illustrated in Fig. HA, the socket A can be mounted to the plate frame 110 together with an AC socket Bl having a single module dimension. As illustrated in Fig. HB, the socket A can be mounted to the plate frame 110 together with an AC socket B2 having a double module dimension and provided with a grounding electrode.

In this connection, the socket A of the present embodiment is formed to have a single module dimension. The transverse dimension of the boss portion of the housing 1

(namely, the portion of the housing 1 exposed through the window opening 111) is substantially equal to the single module dimension of large-square-boss-type interchangeable wiring instruments standardized in Japanese Industrial Standards (namely, equal to about 23 mm) . The longitudinal dimension of the boss portion of the housing 1 is set greater than the single module dimension of the large- square-boss-type interchangeable wiring instruments (namely, equal to about 36 mm) . In the plate unit 100 of the present embodiment, the longitudinal dimension of the window opening 111 is substantially equal to the dimension of the mounting frame for the large-square-boss-type interchangeable wiring instruments standardized in Japanese Industrial Standards . The transverse dimension of the window opening 111 is set greater than that of the large-square-boss-type interchangeable wiring instruments. The socket A and the plate unit 100 of this configuration are used in such countries and regions as the People's Republic of China, the Kingdom of Thailand, the Republic of Indonesia and the Republic of China. In the description made above, the housing 1 of the socket A is formed to have a single module dimension and one receptacle portion 20 is provided on the front surface of the housing 1. Alternatively, as shown in Figs. 12A and 12B, the housing 1 may be formed to have a double module dimension and one or two receptacle portion 20 may be provided on the front surface of the housing 1. As illustrated in Figs. 13A through 13C, the housing 1 may be formed to have a triple module dimension and one or two or three receptacle portion 20 may be provided on the front surface of the housing 1.

In the examples shown in Fig. 12A or Figs. 13A and 13B, a direct current of the same voltage is supplied from the plurality of (two or three) receptacle portions 20. Alternatively, different kinds of electric currents may be supplied from the plurality of receptacle portions 20. Fig. 14A is an internal block diagram of a socket A provided with three receptacle portions 20a through 20c. An alternating current AC of 48V is supplied to power input terminals Tl and T2 (formed of the terminal pieces 9c and the locking springs 10 mentioned earlier) . The alternating current AC of 48V inputted to the input terminals Tl and T2 is outputted to the receptacle portion 20a as it is. An alternating current having a voltage of 24V reduced by a transformer 15 is outputted to the receptacle portion 20b. A direct current of 48V converted by an AC/DC converter is outputted to the receptacle portion 20c. In other words, use of the socket A illustrated in Fig. 14A makes it possible to supply alternating currents having two kinds of voltage values (48V and 24V) and a direct current of one kind (48V) . Fig. 14B is a block diagram showing another example of the socket A. A direct current E of 48V is supplied to power input terminals Tl and T2. The direct current E of 48V inputted to the input terminals Tl and T2 is outputted to the receptacle portion 20a as it is. A direct current having a voltage of 24V obtained by converting the voltage value of the inputted current with a DC/DC converter 17a is outputted to the receptacle portion 20b. A direct current having a voltage of 12V obtained by converting the voltage value of the inputted current with a DC/DC converter 17b is outputted to the receptacle portion 20c. In other words, use of the socket A illustrated in Fig. 14B makes it possible to supply direct currents having three kinds of voltage values (48V, 24V and 12V) .

(Second Embodiment) A wiring device in accordance with a second embodiment of the present invention will be described with reference to Figs. 15 through 19. The wiring device of the present invention differs from that of the first embodiment in that the socket A includes a grounding terminal connection portion 27 provided in the receptacle portion 20, the grounding electrode pin terminal of the plug 200 being connected to the grounding terminal connection portion 27. Except for the provision of the grounding terminal connection portion 27, the wiring device of the present embodiment is the same as that of the first embodiment. The common elements will be designated by like reference characters and will be omitted from description.

As in the first embodiment, a receptacle portion 20, to which a plug 200 is removably inserted, is provided on the front surface of a housing 1 of the socket A. In the present embodiment, a plug 200 with a grounding electrode can be connected to the receptacle portion 20.

The plug 200 with a grounding electrode will be first described with reference to Fig. 17A. The plug 200 is connected to the end of an electric cable 210 extending from a load device. The plug 200 includes a generally rectangular hexahedral grip portion 201, one surface of which is rounded to have a semicircular cross section, and a coupling portion 202 formed at the front end of the grip portion 201, the coupling portion 202 being smaller in width than the grip portion 201. A coupling hole 203 recessed in a circular shape is opened at one side of the front surface of the coupling portion 202 (namely, at the side nearer to the semicircular curved surface) , and a coupling hole 207 recessed in a rectangular shape is opened at the other side of the front surface of the coupling portion 202. A specified gap is left between the coupling holes 203 and 207. A grounding electrode pin terminal 204c made of a conductive material and formed into a circular rod shape is arranged within the rectangular coupling hole 207 in an off- centered position. Two voltage electrode pin terminals 204a and 204b made of a conductive material and formed into a circular rod shape are arranged within the circular coupling hole 203. A reference rib 205 for indicating a reference position and an identification rib 206 for identifying a voltage protrude from the inner circumferential surface of the coupling hole 203. Since the positions of the pin terminals 204a and 204b, the reference rib 205 and the identification rib 206 are the same as those of the plug 200 described in connection with the first embodiment, no description will be made in that regard.

As shown in Figs. 15 and 16, the receptacle portion 20 of the socket A has a plug insertion hole 21 identical in shape and size with the front surface of the coupling portion 202 of the plug 200. The plug 200 is removably inserted into the plug insertion hole 21. A cylindrical columnar protrusion portion 22 for insertion into the coupling hole 203 of the plug 200 and a prismatic columnar protrusion portion 26 for insertion into the coupling hole 207 protrude forwards from the bottom surface of the plug insertion hole 21. The prismatic columnar protrusion portion 26 has a width (i.e., the vertical dimension in Fig. 15B) equal to about one half of the width of the coupling hole 207.

Terminal insertion holes 23a and 23b, into which the voltage electrode pin terminals 204a and 204b are inserted, are opened on the front surface of the cylindrical columnar protrusion portion 22. As in the first embodiment, pin- receiving members 9 are arranged inside the protrusion portion 22 so that the pin-receiving members 9 can be electrically connected to the pin terminals 204a and 204b inserted through the terminal insertion holes 23a and 23b. A terminal insertion hole 26a, into which the grounding electrode pin terminal 204c is inserted, is opened on the front surface of the protrusion portion 26. A grounding electrode pin-receiving member (not shown) having the same shape as the afore-mentioned pin-receiving members 9 is arranged inside the protrusion portion 26 so that the pin terminal 204c inserted through the terminal insertion hole 26a can be electrically connected to the grounding electrode pin-receiving member.

A coupling groove 24 indicating a reference position is formed on the outer circumferential surface of the protrusion portion 22 to extend along the plug insertion- and-removal direction. The terminal insertion holes 23a and 23b are arranged on a straight line passing through the central axis of the protrusion portion 22 and orthogonal to the line segment linking the central axis of the protrusion portion 22 and the coupling groove 24. An identification groove 25 for prevention of erroneous coupling is formed on the outer circumferential surface of the protrusion portion 22, the identification rib 206 of the plug 200 being fitted to the identification groove 25. The position of the identification groove 25 depends on the kinds of power supply (such as a direct current, an alternating current and a rated voltage) . Since the positions of the terminal insertion holes 23a and 23b and the identification groove 25 are the same as those of the socket A described in connection with the first embodiment, no description will be made in that regard.

Three pairs of wire insertion holes 2b (see Fig. 3D) are opened in the rear wall of the body 2. Within the body 2, there are arranged quick-coupling terminals (not shown) to which are connected the electric wires inserted through the wire insertion holes. Two of the three pairs of wire insertion holes are used for connection of external power supply wires, the remaining one for connection of a grounding wire.

As described above, the socket A of the present embodiment includes both the power supply terminal connection portion and the grounding terminal connection portion 27. The power supply terminal connection portion includes the protrusion portion 22 having the terminal insertion holes 23a and 23b opened on the front surface thereof and the pin-receiving members 9 arranged inside the protrusion portion 22. The grounding terminal connection portion 27 includes the protrusion portion 26 having the terminal insertion hole 26a opened on the front surface thereof and the grounding electrode pin-receiving member arranged inside the protrusion portion 26. Thanks to this feature, if the plug 200 having the grounding electrode pin terminal 204c is coupled to the socket A, the voltage electrode pin terminals 204a and 204b of the plug 200 are connected to the power supply terminal connection portion while the grounding electrode pin terminal 204c is connected to the grounding terminal connection portion 27. Therefore, a load device can be electrically grounded by merely coupling the plug 200 to the socket A. This assists in saving the labor required in wiring. Since the power supply terminal connection portion of the socket A complies with IEC Standards, it is possible to couple any type of plug to the socket A so long as the plug is the one complying with IEC Standards . Inasmuch as the grounding terminal connection portion 27 is provided outside the power supply terminal connection portion, it is possible to couple a plug 200 having no grounding electrode pin terminal 204c to the socket A insofar as the plug 200 is the one complying with IEC Standards .

Although the housing 1 of the socket A is formed to have a single module dimension and one receptacle portion 20 is provided on the front surface of the housing 1, one or two receptacle portion 20 may be provided on the front surface of the housing 1 having a double module dimension as shown in Figs. 18A and 18B. As a further alternative, one or two or three receptacle portion 20 may be provided on the front surface of the housing 1 having a triple module dimension as shown in Figs. 19A through 19C. In the socket A provided with a plurality of receptacle portions 20, it may be possible to arrange a transformer, an AC/DC converter and a DC/DC converter within the socket A in order to transform or convert an electric current. The resultant direct current or alternating current may be outputted from the receptacle portions 20.

(Third Embodiment)

A wiring device in accordance with a third embodiment of the present invention will be described with reference to Figs. 20 through 21. The wiring device of the present invention differs from that of the second embodiment in that the socket A includes a signal terminal connection portion provided in the receptacle portion 20, the signal- transmitting pin terminal of the plug 200 being removably connected to the signal terminal connection portion. Except for the provision of the signal terminal connection portion, the wiring device of the present embodiment is the same as that of the second embodiment. The common elements will be designated by like reference characters and will be omitted from description. Fig. 2OB shows a plug 200 with a grounding terminal and a signal terminal. A grounding electrode pin terminal 204c made of a conductive material and formed into a circular rod shape is arranged within the coupling hole 207 of the coupling portion 202 in an upper position in Fig. 2OB. Two signal-transmitting terminal pieces 208a and 208b made of a conductive material and formed into a band plate shape are arranged side by side in a lower position in Fig. 2OB. In other words, the signal-transmitting terminal pieces 208a and 208b are arranged outside the coupling hole 203 in which the voltage electrode pin terminals 204a and 204b are disposed (namely, inside the coupling hole 207) , so that they can extend in the plug insertion-and-removal direction.

As in the second embodiment, a prismatic columnar protrusion portion 26 to be inserted into the coupling hole 207 of the plug 200 is arranged within the plug insertion hole 21 of the receptacle portion 20 of the socket A to protrude forwards. The protrusion portion 26 is formed to have substantially the same size as that of the coupling hole 207. Opened on the front surface of the protrusion portion 26 are a terminal insertion hole 26a into which the grounding electrode pin terminal 204c is inserted and rectangular terminal insertion holes 26b and 26c into which the signal-transmitting terminal pieces 208a and 208b are respectively inserted. Pin-receiving members (not shown) having the same shape as the afore-mentioned pin-receiving members 9 are arranged inside the protrusion portion 26. The pin terminal 204c inserted through the terminal insertion hole 26a is electrically connected to the grounding electrode pin-receiving member, while the terminal pieces 208a and 208b inserted through the terminal insertion holes 26b and 26c are electrically connected to the signal- transmitting pin-receiving members.

In this connection, a signal terminal connection portion 28 is constructed from the protrusion portion 26, the terminal insertion holes 26b and 26c, and the pin- receiving members electrically connected to the terminal pieces 208a and 208b inserted inside the protrusion portion 26 through the terminal insertion holes 26b and 26c. The signal terminal connection portion 28 is arranged in a different position than the power supply terminal connection portion and is electrically connected to the signal- transmitting terminal pieces 208a and 208b of the plug 200. Moreover, a grounding terminal connection portion 27 is constructed from the protrusion portion 26, the terminal insertion hole 26a, and the pin-receiving member electrically connected to the pin terminal 204c inserted inside the protrusion portion 26 through the terminal insertion hole 26a.

As described above, the socket A of the present embodiment includes the power supply terminal connection portion, the grounding terminal connection portion 27 and the signal terminal connection portion 28. The power supply terminal connection portion includes the protrusion portion 22 having the terminal insertion holes 23a and 23b opened at the front surface thereof and the pin-receiving members 9 arranged inside the protrusion portion 22. Thanks to this feature, if the plug 200 with a grounding terminal and signal terminals is coupled to the socket A, the voltage electrode pin terminals 204a and 204b of the plug 200 are connected to the power supply terminal connection portion while the grounding electrode pin terminal 204c is connected to the grounding terminal connection portion 27. Furthermore, the terminal pieces 208a and 208b serving as signal terminals are connected to the signal terminal connection portion 28. By merely coupling the plug 200 to the socket A, therefore, it is possible to electrically connect the signal-transmitting terminals of a load device to the signal line connected to the socket A and also to electrically ground the load device whose plug 200 is coupled to the receptacle portion 20. This assists in saving the labor required in wiring connection. Since the power supply terminal connection portion of the socket A complies with IEC Standards, it is possible to couple any type of plug to the socket A so long as the plug is the one complying with IEC Standards. Inasmuch as the signal terminal connection portion 28 is provided outside the power supply terminal connection portion, it is possible to couple a plug having no signal-transmitting terminal pieces 208a and 208b to the socket A insofar as the plug is the one complying with IEC Standards .

Although the socket A of the present embodiment includes the grounding terminal connection portion 27 in addition to the signal terminal connection portion 28, it may be possible to eliminate the grounding terminal connection portion 27 so that, as shown in Fig. 2IA, the socket A includes only the power supply terminal connection portion and the signal terminal connection portion 28. In this case, as shown in Fig. 21B, the plug 200 provided with the signal-transmitting terminal pieces 208a and 208b as well as the voltage electrode pin terminals 204a and 204b can be coupled to the socket A. (Fourth Embodiment)

A wiring device in accordance with a fourth embodiment of the present invention will be described with reference to Figs. 22 through 25. The wiring device of the present embodiment includes a socket A and a mounting frame 60 (or a frame member) used in arranging the socket A within an embedding pocket formed on a wall surface. The socket A includes a housing 1 of generally- rectangular hexahedral shape. A protuberance Ia having a circular shape when seen in a plan view is formed on the front surface of the housing 1. The same receptacle portion 20 as described in connection with the first embodiment is provided in the protuberance Ia. On the left and right surfaces of the housing 1, there are arranged screw terminals 18 for connection of electric wires extending from an external power source. The housing 1 of the socket A is formed into a shape and size complying with Section W6D of NEMA Standards (Standards of National Electric Manufacturers Association, U.S.A.). Therefore, the socket A has the same shape as that of the sockets used in U.S.A. or like other countries . The mounting frame 60, which is made of a metal, includes a generally U-shaped portion 61 making contact with the upper and lower surfaces and the rear surface of the housing 1 of the socket A and bracket pieces 62 respectively protruding outwards (or upwards and downwards) from the tip ends of upper and lower pieces of the U-shaped portion 61. The U-shaped portion 61 is continuously and integrally formed with the bracket pieces 62. Each of the bracket pieces 62 has a box hole 63 into which to insert a box screw for fixing the mounting frame 60 to a flush-mount box (not shown) attached to a wall surface and a screw hole 64 into which to insert a plate screw 66 to threadedly fix a decoration plate 65 to the front surface of the mounting frame 60. The decoration plate 65 includes a major portion 65a of flat rectangular shape and a rim portion protruding rearwards from the periphery of the major portion 65a. At the central area of the major portion 65a, there is formed a circular window opening 65b through which to expose the protuberance Ia of the housing 1 of the socket A.

As described above, the housing 1 of the socket A of the present embodiment is formed into a shape and size complying with NEMA Standards. This means that the socket A can be mounted in an embedded state by use of the mounting frame 60 suitable for use with a flush-mounted wiring instrument complying with NEMA Standards . If the decoration plate 65 is attached to the front surface of the mounting frame 60, the protuberance Ia of the socket A is exposed from the window opening 65b of the decoration plate 65. Thus, the plug 200 can be removably coupled to the receptacle portion 20 of the socket A.

Although the socket A shown in Fig. 22 includes only the power supply terminal connection portion, the grounding terminal connection portion 27 described in connection with the second embodiment may be added to the receptacle portion 20 as illustrated in Fig. 23. The signal terminal connection portion 28 set forth in respect of the third embodiment may be added to the receptacle portion 20. Both the grounding terminal connection portion 27 and the signal terminal connection portion 28 may be added to the receptacle portion 20.

Although the afore-mentioned socket A includes only one receptacle portion 20, it may be possible to install two receptacle portions 20 in the socket A as illustrated in Fig. 24. The socket A shown in Fig. 24 includes a housing 1 of transversely-elongated rectangular hexahedral shape. On the upper and lower sides of the front surface of the housing 1, there are formed protuberances Ia having a generally elliptical shape when seen in a plan view. The receptacle portion 20 described with regard to the first embodiment is installed in each of the protuberances Ia. Attached to the front surface of the mounting frame 60 is a decoration plate 65 which includes a major portion 65a having window openings 65b formed in the positions corresponding to the protuberances Ia. The respective protuberances Ia are exposed through the window openings 65b.

Although the socket A shown in Fig. 24 includes only the power supply terminal connection portion, the grounding terminal connection portion 27 described in connection with the second embodiment may be added to the receptacle portion 20 (see Fig. 25) . The signal terminal connection portion 28 set forth in respect of the third embodiment may be added to the receptacle portion 20. Both the grounding terminal connection portion 27 and the signal terminal connection portion 28 may be added to the receptacle portion 20. (Fifth Embodiment)

A wiring device in accordance with a fifth embodiment of the present invention will be described with reference to Figs. 26 through 34. The wiring device of the present embodiment includes a mounting frame 190 fixed to a BS box 300 predominantly used in the United Kingdom and the Middle and Near East or a GB box 310 mainly used in the People's Republic of China and a socket A attached to the mounting frame 190. As shown in Fig. 261, the BS box 300 has a generally box- like shape with an open front surface. Tongue pieces 302 each having a screw hole 301 protrude from the medial portions of the upper, lower, left and right sides of the rim of the BS box 300. As illustrated in Fig. 26H, the GB box 310 has a generally box-like shape with an open front surface. Tongue pieces 312 each having a screw hole 311 protrude from the medial portions of the left and right sides of the rim of the GB box 310.

Referring to Figs. 26E and Figs. 28A and 28B, the mounting frame 190 has a generally rectangular shape. A window opening 191, into which a flush-mounted wiring instrument is inserted, is formed in the generally central area of the mounting frame 190. The mounting frame 190 includes four frame pieces having screw insertion holes 192 into which to insert box screws threadedly engaging with screw holes 301 or 311 of the BS box 300 or the GB box 310. Step portions 193 recessed from the front surface of the mounting frame 190 are formed in the upper and lower frame pieces to extend along the peripheral edges of the window opening 191.

As can be seen in Figs. 27A and 27B, the socket A includes a housing 1 of generally rectangular hexahedral shape. A flange Ib protrudes sidewise from the frontal periphery of the housing 1. On the upper and lower surfaces of the housing 1, there are formed elastic locking pieces Ic for gripping the frame pieces of the mounting frame 190 between themselves and the rear surface of the flange Ib. The same receptacle portion 20 as described in respect of the first embodiment is provided on the front surface of the housing 1. The receptacle portion 20 is the same as that of the first embodiment and, therefore, will be omitted from description.

The housing 1 of the socket A shown in Figs. 26A, 27A and 27B has a vertical dimension of 42 to 46 mm and a transverse dimension of 22 to 23 mm which is equal to about one half of the transverse dimension of the window opening 191. This makes it possible to attach two sockets A to the mounting frame 190 side by side. The socket A includes only one receptacle portion 20. In contrast, the housing 1 of each of the sockets A shown in Figs. 26B through 26D has a vertical dimension substantially equal to the transverse dimension of the window opening 191. The sockets A include one or two or three receptacle portion 20. The sockets A shown in Figs. 26 and 27 do not include any grounding terminal connection portion to which the grounding electrode pin terminal of a plug is connected nor any signal terminal connection portion to which signal-transmitting pin terminals are connected. Alternatively, as shown in Figs. 3OA through 3OC, the grounding terminal connection portion 27 described in connection with the second embodiment may be added to the receptacle portion 20. The signal terminal connection portion 28 set forth in respect of the third embodiment may be added to the receptacle portion 20. Both the grounding terminal connection portion 27 and the signal terminal connection portion 28 may be added to the receptacle portion 20.

When fixing the socket A to a wall surface, the housing 1 of the socket A is first inserted from the front side into the window opening 191 of the mounting frame 190 with the flange Ib of the housing 1 facing forwards. If the rear surface of the flange Ib comes into contact with the step portions 193 of the periphery of the window opening 191, the elastic locking pieces Ic make contact with the upper and lower frame pieces of the mounting frame 190 from the rear side. Thus, the mounting frame 190 is gripped between the flange Ib and the elastic locking pieces Ic, as a result of which the housing 1 is attached to the mounting frame 190 (see Fig. 29) . Thereafter, if the box screws (not shown) inserted into the screw insertion holes 192 of the mounting frame 190 are threadedly engaged with the screw holes 301 or 311 of the BS box 300 or the GB box 310, the mounting frame 190 holding the housing 1 of the socket A is mounted to the BS box 300 or the GB box 310. The housing 1 of the socket A set forth just above can also be mounted to a C box 320, i.e., a flush-mount box used in the German Federal Republic, the French Republic, the Republic of Indonesia and other countries. A mounting frame 140 is used in mounting the housing 1 to the C box 320. As shown in Fig. 26J, the C box 320 is of closed-bottom cylindrical shape with an open front surface. In the opening of the C box 320, tongue pieces 322 each having a screw hole 321 protrude in a symmetrical relationship with respect to the axis of the C box 320. Referring to Fig. 26F, the mounting frame 140 is of rectangular shape. A window opening 141, into which a flush-mounted wiring instrument is inserted, is formed in the generally central area of the mounting frame 140. The mounting frame 140 includes left and right frame pieces having screw insertion holes 142 into which to insert box screws threadedly engaging with screw holes 321 of the C box 320. The mounting frame 140 further includes upper and lower frame pieces having step portions 143 which are recessed from the front surface and extend along the peripheral edges of the window opening 141. When arranging the housing 1 of the socket A within the C box 320 in an embedded state, the housing 1 of the socket A is first inserted from the front side into the window opening 141 of the mounting frame 140 with the flange Ib of the housing 1 facing forwards . If the rear surface of the flange Ib comes into contact with the step portions 143 of the periphery of the window opening 141, the elastic locking pieces Ic make contact with the upper and lower frame pieces of the mounting frame 140 from the rear side. Thus, the mounting frame 140 is gripped between the flange Ib and the elastic locking pieces Ic, as a result of which the housing 1 is attached to the mounting frame 140. Thereafter, if the box screws (not shown) inserted into the screw insertion holes 142 of the mounting frame 140 are threadedly engaged with the screw holes 321 of the C box 320, the mounting frame 140 holding the housing 1 of the socket A is mounted to the C box 320.

The housing 1 of the socket A set forth just above can also be mounted to an A box 330, i.e., a flush-mount box used in such countries and regions as Japan, U.S.A. and Republic of China. A mounting frame 150 is used in mounting the housing 1 to the A box 330. As shown in Fig. 26K, the A box 330 is of substantially box-like shape with an open front surface. In the opening of the A box 330, tongue pieces 332 each having a screw hole 331 protrude from the medial portions of the upper and lower sidewalls. Referring to Fig. 26G, the mounting frame 150 is of generally rectangular shape. A window opening 151, into which a flush-mounted wiring instrument is inserted, is formed in the generally central area of the mounting frame 150. The mounting frame 140 includes upper and lower frame pieces having screw insertion holes 152 into which to insert box screws threadedly engaging with screw holes 331 of the A box 330. The A box 330 refers to a flush-mount box of the type used in U.S.A. and complies with NEMA Standards.

When arranging the housing 1 of the socket A within the A box 330 in an embedded state, the housing 1 of the socket A is first inserted from the front side into the window opening 151 of the mounting frame 150 with the flange Ib of the housing 1 facing forwards. If the rear surface of the flange Ib comes into contact with the step portions 153 of the periphery of the window opening 151, the elastic locking pieces Ic make contact with the left and right frame pieces of the mounting frame 150 from the rear side. Thus, the mounting frame 150 is gripped between the flange Ib and the elastic locking pieces Ic, as a result of which the housing 1 is attached to the mounting frame 150. Thereafter, if the box screws (not shown) inserted into the screw insertion holes 152 of the mounting frame 150 are threadedly engaged with the screw holes 331 of the A box 330, the mounting frame 150 holding the housing 1 of the socket A is mounted to the A box 330. Although the housing 1 of the socket A is formed independently of the mounting frame in the present embodiment, it may be possible to integrally form the housing 1 of the socket A and the mounting frame as a unit. For example, the housing 160 of the socket A illustrated in Fig. 31A is formed by unifying the housing 1 of the socket A shown in Figs. 26A to 26K and the mounting frame 190 designed to be mounted to the BS box 300 or the GB box 310. More specifically, the housing 160 includes a box- like body portion 161 having a receptacle portion 20 on its front surface and a flange portion 163 protruding sidewise from the frontal periphery of the body portion 161, wherein the body portion 161 and the flange portion 163 are formed as a unit. Screw insertion holes 162 are formed in the medial areas of the respective sides of the flange portion 163. A decoration plate 170 having a window opening 171 through which to expose the front surface of the body portion 161 is removably attached to the front side of the housing 160. The receptacle portion 20 of the body portion 161 is exposed through the window opening 171. Since the housing 160 is unified with the mounting frame as mentioned above, it is possible to attach the housing 160 to the flush-mount box (namely, the BS box 300 or the GB box 310) without having to use any independent mounting frame, which assists in reducing the number of parts. The BS box refers to a flush- mount box complying with BS Standards of the United Kingdom. The GB box refers to a flush-mount box complying with GB Standards stipulated by the National Standardization Management Committee of the People's Republic of China.

Although the housing 160 of the socket A shown in Fig. 31A is unified with the mounting frame, it may be possible to employ a housing 165 unified with the mounting frame and the decoration plate 170 as shown in Fig. 3IB. Reference numeral 166 in Fig. 31B designates screw insertion holes into which to insert box screws. Since the housing 165 is unified with the mounting frame and the decoration plate in the socket A mentioned just above, it is possible to attach the housing 165 to the flush-mount box (namely, the BS box 300 or the GB box 310) without having to use any independent mounting frame and decoration plate, which assists in further reducing the number of parts. The sockets A shown in Figs. 31A and 31B do not include any grounding terminal connection portion to which the grounding electrode pin terminal of a plug is connected nor any signal terminal connection portion to which signal-transmitting pin terminals are connected. Alternatively, as shown in Figs. 33A and 33B, the grounding terminal connection portion 27 described in connection with the second embodiment may be added to the receptacle portion 20. The signal terminal connection portion 28 set forth in respect of the third embodiment may be added to the receptacle portion 20. Both the grounding terminal connection portion 27 and the signal terminal connection portion 28 may be added to the receptacle portion 20. Although the housing is unified with the mounting frame 190 to be mounted to the BS box 300 or the GB box 310 in the socket A shown in Figs. 31 and 33, it may possible to employ a housing 180 unified with the mounting frame 140 to be attached to the C box 320 as illustrated in Fig. 32A. The housing 180 includes a box-like body portion 181 having a receptacle portion 20 on its front surface and a flange portion 183 protruding sidewise from the frontal periphery of the body portion 181, wherein the body portion 181 and the flange portion 183 are formed as a unit. Screw insertion holes 182 are formed in the medial areas of the respective sides of the flange portion 183. A decoration plate 170 having a window opening 171 through which to expose the front surface of the body portion 181 is removably attached to the front side of the housing 180. The receptacle portion 20 of the body portion 181 is exposed through the window opening 171. Since the housing 180 is unified with the mounting frame as mentioned above, it is possible to attach the housing 180 to the flush-mount box (namely, the C box 320) without having to use any independent mounting frame. The C box refers to a flush- mount box complying with Standards of European countries such as the German Federal Republic, the French Republic and so forth. Although the housing 180 of the socket A shown in Fig. 32A is unified with the mounting frame, it may be possible to employ a housing 185 unified with the mounting frame and the decoration plate 170 as shown in Fig. 32B. Reference numeral 186 in Fig. 32B designates screw insertion holes into which to insert box screws. Since the housing 185 is unified with the mounting frame and the decoration plate in the socket A mentioned just above, it is possible to attach the housing 185 to the flush-mount box (namely, the C box 320) without having to use any independent mounting frame and decoration plate, which assists in reducing the number of parts. The sockets A shown in Figs. 32A and 31B do not include any grounding terminal connection portion to which the grounding electrode pin terminal of a plug is connected nor any signal terminal connection portion to which signal- transmitting pin terminals are connected. Alternatively, as shown in Figs. 34A through 34C, the grounding terminal connection portion 27 described in connection with the second embodiment may be added to the receptacle portion 20. The signal terminal connection portion 28 set forth in respect of the third embodiment may be added to the receptacle portion 20. Both the grounding terminal connection portion 27 and the signal terminal connection portion 28 may be added to the receptacle portion 20.

In the first through fourth embodiments, the housing of the socket may be formed by unifying the socket body and the frame member as is the case in the present embodiment. This makes it possible to mount the housing within the flush-mount box in an embedded state without having to use a frame member formed independently of the housing of the socket, which assists in reducing the number of parts.

While the invention has been shown and described with respect to the embodiments, it will be understood by those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims .