GB2298973A

GB2298973A - Terminal structure for a wiring device

Info

Publication number: GB2298973A
Application number: GB9604984A
Authority: GB
Inventors: Masami Hayafune; Manabu Yano; Yasuhiro Sumino; Masashi Sakabe; Hideaki Ujihara
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1995-03-15
Filing date: 1996-03-08
Publication date: 1996-09-18
Anticipated expiration: 2016-03-08
Also published as: GB9604984D0; JPH08315871A; JP3605923B2; GB2298973B; CN1080002C; CN1141518A; MY112036A

Abstract

A terminal structure for detachably connecting a plurality of cords to a common terminal member 22 included in a wiring device. The terminal structure comprises a housing 10 with a plurality of cord insertion holes leading to a common compartment 12 formed within the housing and a plurality of lock springs 30 disposed within the compartment together with the common terminal member 22 to hold wires of the cords in engagement with the terminal member. Separators 27, 29 are disposed in the compartment for separating the lock springs from each other in order to prevent the jamming of the wires inserted into the compartment through the individual cord insertion holes, thereby facilitating the connection of the plural cords to the wiring device. The lock springs 30 each include a cord 5 engagement portion 31 and a cord holding pawl 32 releasable from the cord 5 by a tool operated release button 40. Insulating or grounded mounting frames, covers and a shutter 62 are provided for an outlet having an indicating lamp 58 and a switch in which contact 57 is closed and opened by a sprung member 52 pivoting on a support 54 (see figure 8)

Description

WIRING DEVICE The present invention is directed to a wiring device, for example, an electrical receptacle and switch box having a terminal structure for connecting a plurality of cords to a common terminal member.

In order to facilitate wire connection, prior wiring devices have been proposed to include a rapid connection structure which includes lock springs for engaging wires of cords with a terminal member mounted in a housing. With the use of the lock springs, the wires can be engaged with the terminal member simply by inserting the cords into between the lock springs and the terminal member through cord insertion holes in the housing. In the wiring device which requires a plurality of the cords to be connected commonly to the one terminal member, it is usual to arrange a plurality of the lock springs equal in number to the cords in a single compartment together with the terminal member.In this consequence, even if the cords are guided through the separate cord insertion holes, the cord reaching the single compartment may be led to adjacent, i.e., wrong lock spring or springs, which gives rise to jamming of the cords to thereby prolong the connecting operation or even fails to connecting the wires to the terminal member. This is particularly true when the wire of the cord comprises twisted filaments.

The above problem has been solved in the present invention which provides a terminal structure of a wiring device capable of facilitating correct connection of the cords to the common terminal member. The terminal structure in accordance with the present invention comprises a housing provided with a plurality of cord insertion holes leading to a common compartment formed within the housing, and a plurality of lock springs disposed within the compartment together with the common terminal member to hold wires of the cords in engagement with the terminal member. Separators are disposed within the compartment for separating the lock springs from each other.

Accordingly, the wires guided into the compartment can be successfully led to the associated lock springs for correct and easy connection to the terminal member.

Preferably, the separators are formed integrally with the terminal member. For instance, the separators are formed as integral parts which are bent from a main portion of the terminal member. Additional separators may be formed integrally with the terminal member.

The above and other advantageous features will become apparent from the following description of the preferred embodiments which are described by way of example only with reference to the attached drawings in which: FIG. 1 is an exploded perspective view of a wiring device in accordance with a preferred embodiment of the present invention; FIG. 2 is an exploded perspective view illustrating an internal structure of the wiring device; FIG. 3 is a top view of the wiring device; FIG. 4 is a bottom view of the wiring device; FIG. 5 is a top view of a body of the wiring device; FIGS. 6 to 9 are vertical sections of the wiring device; FIG. 10 is a perspective view of a release button utilized in the wiring device; FIG. 11 is a sectional view of illustrating the release button and a lock spring utilized in the wiring device;; FIGS. 12A, 12B, and 12C are explanatory views illustrating operation of the release button; FIG. 13 is a fractional perspective view of a portion of a cover of the wiring device; FIGS. 14A and 14B are explanatory views respectively illustrating structures of engaging the cover to a mount frame; FIG. 15 is an exploded perspective view illustrating another mount frame and associated face plate utilized for mounting the wiring device; FIG. 16 is a sectional view of the wiring device supported to the mount frame of FIG. 15; FIG. 17 is a top view illustrating the wiring device supported to the mount frame of FIG. 15; FIGS. 18A and 18B are explanatory views illustrating an operation of fixing the wiring device to the mount frame of FIG. 15; FIG. 19 is an exploded perspective view of a modified wiring device;; FIG. 20 is an exploded perspective view illustrating a mount frame and a fact plate for use with the wiring device of FIG. 19; FIG. 21 is a sectional view of the wiring device with the mount frame; FIGS. 22A, 22B, and 22C are explanatory views illustrating an operation of connecting a ground prong to the mount frame; FIG. 23 illustrates a modified mount frame adapted to carry two wiring devices; FIG. 24 illustrates a further modified mount frame adapted to carry two wiring devices; and FIG. 25 illustrates a still further modified mount frame and an associated face plate for the wiring device.

Referring now to FIGS. 1 to 4, there is shown a wiring device in accordance with a preferred embodiment of the present invention. The wiring device in this embodiment is an electrical receptacle of grounded type with three slots made in conformity with the British Standard (BS), although the present invention is not limited to this specific structure.

The receptacle is of the type permitting a plurality of cords to be connected to each one of the terminals. The receptacle 1 further includes a switch and is installed to a wall by the use of a mount frame 80 and a face plate 90. The receptacle 1 has a rectangular housing composed of a top-open body 10 and a cover 70 which are made of electrically insulative plastic material and are fastened by means of screws 2.

As shown in FIG. 2, the body 10 is formed with three cells 11 accommodating therein three sockets 21 into which prongs of a plug (not shown) are inserted through slots 71 in the cover 70. Also formed in the body 10 are three compartments 12 accommodating therein three terminal members 22 for connection with external cords by the use of lock springs 30. The two left and center terminal members 22 as seen in FIG. 2 are integrally connected respectively to the two sockets 21 by way of bridge members 23. The remaining one right terminal member 22 is connected to the right socket 21 through a switch mechanism the detail of which will be discussed later. In this embodiment, the center terminal 22 is defined as a grounding terminal to be connected to a grounding cord or cords.

Each of the terminal members 22 comprises three pairs of opposed terminal legs 24 and 25 which depend integrally from a common web 26 to receive each one of the lock springs 30 between each opposed pair of the terminal legs 24 and 25. Also depending from the web 26 are a pair of separator legs 27 which extend into the compartment 12 to divide the interior of the compartment into three separate spaces each receiving each of the three lock springs 30. Further, two adjacent terminal legs 24 are formed with auxiliary separators 29 bent towards the separator legs 27 and arranged in alignment therewith for holding each of the lock springs 30 into each separate space in cooperation with the separator legs 27. A slit is formed in a bent portion of the separator 29 for facilitating the bending of the separator from the terminal leg 24.

The lock spring 30 is utilized for rapid connection of wire of the cord to the terminal member 22. The cords are introduced through individual insertion holes 13 formed in the body 10 to extend from the compartment 12 and open to the bottom of the body, as shown in FIGS.

4, 6, and 7. The lock spring 30 is configured to have a pressing segment 31 and a barb extension 32 at opposite ends thereof, as best shown in FIG. 11. The pressing segment 31 and the barb extension 32 are urged towards the terminal leg 25 so as to engage with the wire 6 of the cord 5 introduced into the compartment 12 along the terminal leg 25. In this condition, the barb extension 32 bites into the wire to prevent the disengagement of the wire. The inner end of each insertion hole 13 is tapered to have a generally square configuration in order to facilitate the insertion of the wire 6 of the cord 5 into the compartment 12 for engaging the wire between the terminal leg 25 and the lock spring 30.

That is, as the cord is inserted through the hole 13, the wire can be aligned ready for being engaged between the lock spring 30 and the terminal leg 25. This is particularly advantageous when the wire is made of twisted filaments.

Associated with each of the terminal members 22 is a release button 40 which is movable from a lock position of keeping the engagement of the wire by the lock springs 30 and a release position of allowing the wire or wires to be disengaged from the lock springs 30. As best shown in FIG. 10, the release button 40 comprises a base 41 with an enlarged head 42 and is disposed adjacent to the lock springs 30 with the enlarged head 42 extending into the compartment 12 and with the base 41 retained in a buttonhole 14 formed adjacent to the cord insertion holes 13 and separated therefrom, as shown in FIGS. 4, 6, 7, 11, and 12A to 12C.The enlarged head 42 has its front end engaged with the barb extensions 32 of the all three lock springs 30 in the same compartment 12 so as to slacken the three lock springs 30 simultaneously, thereby allowing the wires to be pulled away from the receptacle 1 when the release button 40 is moved inwardly, as shown in FIGS. 12A to 12C. The base 41 has an arcuate surface 43 which is in sliding engagement with a correspondingly curved wall surface 15 of the buttonhole 14 so as to allow the sliding movement of the release button 40 between the lock position and the release position. The base 41 is formed on its opposite side edges with rims 44 which are fit into corresponding grooves for guiding the sliding movement of the release button 40.

Further, the enlarged head 42 is kept in contact with edges 28 of the two adjacent separator legs 27 during the movement of the release button 40 between the lock and release positions. In this sense, the edges 28 serves as an additional guide for the release button 40. The wires can be disengaged from the lock springs 30 simply by inserting a blade 8 of a screwdriver into a slot formed in the buttonhole 14 between the base 41 and the wall of the buttonhole, as shown in FIGS. 12A to 12C. As the blade 8 is advanced inwardly from the position of FIGS.

12A to the position of FIG. 12B, the barb extension 32 is resiliently deformed inwardly to release the wire 6, thereby allowing the wire 5 to be pulled away, as show in FIG. 12C. In this condition, the barb extension 32 gives a counter spring force to urge the release button 40 in the direction indicated by an arrow in FIG. 12C, thereby holding the blade 8 against the wall of the buttonhole 14. Consequently, the release button 40 is kept in the release position until the blade of the screwdriver is removed intentionally from the receptacle, thereby avoiding the barb extension 42 from springing back to bite again the wires being pulled and therefore facilitating the disengagement of the wires from the receptacle.

When assembling the terminal structure, the release button 40 is firstly inserted into the compartment 12 with the base 41 extending into the buttonhole 14 after which the lock springs 30 and the terminal member 22 are put into the compartment 12. In order to prevent the terminal legs 25 from interfering with the release button 40 when assembling the terminal member 22 into the body 10, a pair of notches 45 are formed in the front edge of the head 42 in registration with the terminal legs 25. The terminal legs 25 extending past the head 42 of the release button 40 are fitted into catches 16 formed in the body 10, as shown in FIG. 11, for exact positioning of the terminal legs 25.As shown in FIGS. 10 and 11, the release button 40 is formed on the end of the base 41 with a stopper 46 which projects into a clearance formed between the base 41 and the wall of the buttonhole 14 opposite of the slot for receiving the blade of the screwdriver. With the presence of the stopper 45, wrong insertion of the screwdriver into the clearance can be avoided.

Turning back to FIG. 2 and 8, the switch comprises a switch handle 50 pivotally supported within an opening 72 in the cover 70 and connected through an overcenter spring 51 to a cradle 52 with a movable contact 53. The cradle 52 is held on a fulcrum 55 formed at the end of a conductor lead 54 extending from the right socket 21 in FIG. 2. Thus, the cradle 52 is responsive to the swinging movement of the handle 50 for closing and opening the movable contact 53 to and from a fixed contact 57 formed on the end of another conductor lead 56 extending from the right terminal member 22. A pilot lamp 58 is connected between the conductor lead 54 of the right socket 21 and left socket 21, as shown in FIG. 2. The pilot lamp 58 is visible through a transparent cap 59 fitted in the cover 70.

As shown in FIGS. 2, 5, 7 and 9, a shutter 60 is provided in the body 10 to normally close the slots 71 of the cover 70. The shutter 60 comprises a center member 61 formed at one end thereof with a door 62 and with an inclined guide 63 at the other end. The shutter 60 is biased by a spring 65 into a close position where the door 62 is positioned over the adjacent sockets 21 and the inclined guide 63 is positioned over the remaining socket 21, as best shown in FIG. 5. When the prongs of the plug are inserted into the slots 71 of the receptacle, one of the prongs abuts first against the inclined guide 63 to thereby apply a force of moving the shutter 60 against the spring 65 to expose all the three sockets 71, enabling the connection of the plug to the receptacle.

The cover 70 is formed on each of opposite front and rear ends with two pairs of joints for connection with the mount frame 80. As shown in FIGS. 1 and 13, the first pair of joints on each of the front and rear ends of the cover 70 comprise latches 73 projecting from the upper edge of the cover and having inclined top surfaces. The pair of the latches 73 on the front end are staggered horizontally with respect to those on the rear end of the cover. The second pair of joints on the front end of the cover comprise hooks 75 positioned downward and outwardly of the latches 73. Cavities 77 are formed in the front end of the cover 70 immediately adjacent to the upper end of each hook 75. As shown in FIG. 13, the second pair of joints on the rear end of the cover 70 comprise notches 76 formed inwardly of the adjacent latches 73.

The mount frame 80 is made of an electrically insulative plastic material and is formed with a center opening 81 for receiving therein the cover 70 of the receptacle 1, as shown in FIG. 1. For connection with the cover 70, the mount frame 80 is formed in each of its front and rear edges on opposite of the opening with a pair of dents 83 into which the latches 73 of the cover 70 engage, as shown in FIGS. 14A and 14B.

A pair of cuts 85 are formed in the front edge of the mount frame 80 for engagement with the hooks 75 of the cover 70, as shown in FIGS. 8 and 14A. Further, a tongue 86 projects on the rear inner edge of the mount frame 80 to engage into the notches 76 in the rear end of the cover 70, as shown in FIG. 14B. The cover 70 is secured to the mount frame 80 by snap connection into a unitary assembly so as to be mounted to a wall surface simply by fixing the mount frame 80 to a wiring box (not shown) embedded in the wall. For this purpose, the mount frame 80 is formed with elongated holes 82 through which screws extends for connection with the wiring box. The elongated holes 82 permits easy and exact registration of the mount frame 80 to the wiring box.

The above snap connection can be made by use of resilient deformation capability given to the front inner edge of the mount frame 80 by provision of two parallel slits 87 in the frame. That is, the snap connection is easily effected firstly by connecting the rear end of the cover 70 to the rear inner edge of the frame 80 by engagement of the latches 73 and tongue 86 respectively with the dents 83 and the notches 76, and then pressing the front inner edge of the frame against the front end of the cover 70. Whereby, the front inner edge is allowed to flex outwardly to permit the latches 73 and hooks 75 on the front end of the cover 70 to cam over the front inner edge of the frame 80, after which the front inner edge returns inwardly to engage respectively with the dents 83 and cuts 85 in the front inner edge of the frame 80.It is noted in this connection that the staggered arrangement of the latches 73 on opposite front and rear ends of the cover is advantageous for easy and correct registration of the cover 70, i.e., receptacle 1 to the mount frame.

The face plate 90 also made of a like plastic material is fitted over the mount frame 80 to conceal a peripheral portion thereof and, as shown in FIG. 1, has openings 91, 92, and 93 for exposing therethrough the slots 71 of the cover 70, the switch handle 50, and the cap 59 of the pilot lamp 58, respectively. The face plate 90 is formed with integral hooks 94 projecting on the rear side thereof for snap-in engagement with holes 84 in the corners of the mount frame 80. In order to make an easy detachment of the face plate 90, the mount frame 80 is formed with a recess 89 which appears in the mating surface with the face plate 90 and is adapted in use to receive a jig such as the blade of a screwdriver or the like. With the use of the jig, the hooks 94 can be disengaged from the mount frame 80 due to resiliency inherently given to the face plate 90.The recess 89 may be alternately formed in the face plate 90.

FIGS. 15 to 17 illustrates the use of another mount frame 180 with associated face plate 190 for mounting the receptacle as disclosed in the above. The mount frame 180 is made of an electrically conductive metal to have a pair of displaceable projections 187 on the front inner edge and have a pair of fixed projections 186 on the rear inner edge. A grounding prong 188 projects from the rear inner edge for insertion into a grounding hole 121 formed in an extension 120 of the terminal member 22 (shown in FIG. 2) so that the mount frame 180 is grounded.

The face plate 190 is also made of an electrically conductive metal and is connected to the mount frame 180 by means of metal screws 194 engaging into threaded holes 184 in the mount frame 180 so that the face plate 190 is also grounded. The mount frame 180 has like elongated holes 182 for fixing the mount frame to the wiring box by screws.

As best shown in FIGS. 18A and 18B, the displaceable projections 187 are each supported to the mount frame 180 through a pair of integral arms 183 of narrow width in a manner as to leave a cut 185 behind the arms 183 and the projection 187. Connection of the receptacle 1 to the mount frame 180 is made by firstly inserting the projections 186 on the rear inner edge of the mount frame 180 into the notch 76 in the rear end of the cover 70 followed by forcing the projections 187 on the front inner edge of the frame 180 into the cavities 77 in the front end of the cover 70 by use of the blade of a screwdriver as shown in the figures.That is, the blade of the screwdriver inserted in the cut 185 behind the projection 187 is twisted as indicated by arrows in FIG. 18A to displace the projection 187 toward the cavity 77 and is then shifted into the cut behind the arm 183 where it is again twisted as indicated by arrows in FIG. 18B to deform the arm 183 for further displacing the projection 187 into the cavity 77.

FIGS. 19 to 21 illustrate a modification of the above receptacle which is identical in structure to the above embodiment except that a grounding prong 122 projects from a terminal member 22A for insertion into a grounding hole 189 in a like mount frame 180A for grounding the mount frame 180A. Like parts are designated by like numerals with a suffix letter of "A". No duplicate explanation is deemed necessary for the sake of simplify.The grounding prong 122 is bifurcated to have a pair of fingers 123, as shown in FIG. 22A, and is secured the mount frame 180A through the steps of inserting the prong 122 into the grounding hole 189, shifting the mount frame 180 in the direction as indicated by an arrow X in FIG. 22A to engage the projection 186A with the corresponding notches in the rear end of the cover 170A, and bending the fingers 123 away from each other for engagement with the periphery of the grounding hole 189, as shown in FIGS. 22B and 22C.

FIG. 23 illustrates a modified mount frame 80B configured to support the two receptacles 1 of the above embodiment in side-by-side relation. The mount frame 80B is made of an electrically insulative plastic material and have the same structural configurations as the mount frame 80 shown in FIG. 1 except that the frame 80B has a center opening 81A dimensioned to receive the two receptacles 1 and has two mounting structures each identical to that shown in FIG. 1 for the individual receptacles 1. Like parts are designated by like numerals with a suffix letter of "B" for easy reference purpose.

FIG. 24 illustrates another modified mount frame 180C configured to support the receptacles 1 of the above embodiment in side-by-side relation. The mount frame 180C is made of an electrically conductive metal and have the same structural configurations as the mount frame 180 shown in FIGS. 15 to 17 except that the frame 180 has a center opening 181C dimensioned to receive the two receptacles 1 and has two mounting structures each identical to that shown in FIGS. 15 to 17 for the individual receptacles 1. Like parts are designated by like numerals with a suffix letter of "C" for easy reference purpose.

FIG. 25 illustrate a modified cover 70D for a like receptacle as shown in the above embodiment. The cover 70D is formed to have integral flange 80D serving as the mount frame for mounting the receptacle on the wall surface and to the wiring box. For this purpose, the flange 80D is formed with elongated holes 82D through which screws extends for fixing the cover 70D, i.e., the receptacle to the wiring box. Also, holes 84D are formed in the flange 80D for receiving hooks 94D of an associated face plate 90D. Like parts are designated by like numerals with a suffix letter of "D" for easy reference purpose.

It will be appreciated that the term "cord" used throughout this specification should be construed to include a "cable" or other electrical lead.

LIST OF REFERENCE NUMERAlS 1 receptacle 2 screw 5 cord 6 wire 8 blade of screwdriver 10 body 11 cell 12 compartment 13 cord insertion hole 14 buttonhole 15 curved wall surface 16 catch 21 socket 22 terminal member 23 bridge member 24 leg 25 leg 26 web 27 separator leg 28 edge 29 auxiliary leg 30 lock spring 31 pressing segment 32 barb extension 40 release button 41 base 42 enlarged head 43 arcuate surface 44 rim 45 notch 46 stopper 50 switch handle 51 overcenter spring 52 cradle 53 movable contact 54 conductor lead 55 fulcrum 56 conductor lead 57 fixed contact 58 pilot lamp 59 cap 60 shutter 61 center member 62 door 63 inclined guide 70 cover 71 slot 72 opening 73 latch 75 hook 76 notch 77 cavity 80 mount frame 81 opening 82 elongated hole 83 dent 84 hole 85 cut 86 tongue 87 slit 89 recess 90 face plate 91 opening 92 opening 93 opening 94 hook 120 extension 121 grounding hole 122 grounding prong 123 finger LIST OF REFERENCE NUMERALS 180 mount frame 183 arm 184 hole 185 cut 186 projection 187 projection 188 grounding projection 189 grounding hole

Claims

CLAIMS: 1. A terminal structure for detatchably connecting a plurality of cords to a common terminal member of a wiring device, said structure comprising: a housing having a plurality of cord insertion holes leading to a common compartment formed within said housing; a plurality of lock springs disposed within said compartment together with said common terminal member to hold wires of said cords in engagement with said terminal member; separator means disposed within said compartment for separating said lock springs from each other.
2. The terminal structure as set forth in claim 1, wherein said separator means is formed integrally with said terminal member.
3. The terminal structure as set forth in claim 2, wherein said separator means comprises at least one segment which extends integrally from said terminal member through a bent portion, said bent portion being formed with a slit.
4. The terminal structure as set forth in claim 1, wherein said cord insertion holes is shaped to have a rectangular cross section at least in an inward end portion terminating at the interior of said housing.
5. The terminal structure as set forth in claim 1, wherein a release button is movably received in said housing with a front end of said release button engageable with the lock spring, said release button having an arcuate surface in sliding contact with a correspondingly curved wall formed in said housing so that said release button is movable from a lock position of allowing said lock spring to hold said wire to a release position where said front end causes pushes said lock spring to slacken it for disengaging the wire.
6. The terminal structure as set forth in claim 5, wherein said release button is slidably received in a buttonhole formed in said housing and communicating with said compartment, said release button forming a release slot between a rear end of said release button and a wall of said buttonhole for receiving a blade of a screwdriver, said release button being pushed by the blade of said screwdriver inserted in said release slot to said release position where the lock spring is resiliently deformed to disengage said wire as well as to give a counter spring force for biasing said release button in a direction of pressing the blade of the screwdriver against the wall of said buttonhole.
7. The terminal structure as set forth in claim 5 or 6, wherein said separator means includes guide means for guiding said release button for movement between said lock position and said release position.
8. The terminal structure as set forth in claim 6, wherein each said release button formed with a stopper which projects on the rear end of said release button at a portion opposite of said release slot for preventing the entry of said screwdriver into a clearance formed on opposite of said release slot between the rear end of the release button and the wall of said buttonhole, said wall of the button hole formed with a groove for receiving said stopper.
9. An electrical receptacle having the terminal structure of claim 1, wherein said receptacle includes at least two said terminal members each connected to each one of sockets provided in said housing for receiving prongs of a plug, and includes a switch inserted between at least one of said sockets and the associated terminal members.
10. An electrical receptacle having the terminal structure of claim 1, wherein said receptacle includes at least two said terminal members each connected to each one of sockets provided in said housing for receiving prongs of a plug through slots in top of said housing, said receptacle further including a shutter which is movably supported in said housing between an open position of opening all said slots and a close position of closing at least one of said slots, said shutter being formed with an actuator which is exposed through one of said slots in said closed position and receives a force from the corresponding prong when inserted in said slot to thereby move said shutter towards open position, and said housing including spring means for biasing said shutter towards said closed position.
11. A wiring device having said terminal structure of claim 1, wherein said housing comprises a body having said compartment and a cover fitted on said body, one of said body and said cover being formed with a plurality of first joints engageable with second joints formed on a mount frame, said mount frame being given resiliency which allows said first joints to engage with said second joints.
12. The wiring device as set forth in claim 11, wherein said mount frame has an opening into which a portion of said cover extends, said second joints being formed on each of opposed edges of said opening and arranged such that said second joints on one of said opposed edges are staggered with said second joints on the other edge along the length of said edge, said mount frame being formed with a slit immediately adjacent to at least one of said second joints to give the resiliency which allows said at least one second joint to engage with said first joint.
13. The wiring device as set forth in claim 11, wherein a pair of said first joints are formed on each of opposed ends of said cover, the pair of said first joints on one of the opposed ends of said cover being staggered with respect to the pair of said first joint on the other of said opposed ends along a length of said opposed ends.
14. A wiring device having said terminal structure of claim 1, wherein said housing comprises a body having said compartment and a cover fitted on said body, said cover having a mount flange extending beyond said body for mounting said housing to an object surface.
15. A wiring device having said terminal structure of claim 1, wherein said housing comprises a body having said compartment and a cover fitted on said body, one of said body and said cover being formed with a plurality of first joints engageable with a plurality of second joints formed on a mount frame, said second joints being allowed to deform for engagement with said first joints.
16. The wiring device as set forth in claim 12 or 15, wherein a plurality of said housings are supported to a single said mount frame.
17. The wiring device as set forth in any one of claims 12 to 15, wherein said mount frame is made of an electrically conductive material and is integrally formed with an grounding prong which is press-fitted into a grounding hole in said terminal member so that said mount frame is grounded.
18. The wiring device as set forth in any one of claims 11 to 17, wherein said mount frame is connected to a box embedded in a wall on which said wiring device is installed, said mount frame being formed with an elongated hole through which a screw extends for fixing said mount frame to said box.
19. A wiring device having the terminal structure of claim 1, wherein said housing is supported to a separate mount frame and wherein a face plate is placed over said housing and said mount frame, said face plate being formed with a plurality of studs which extend from a rear surface of said face plate for engagement into corresponding catches formed in said mount frame.
20. The wiring device as set forth in claim 19, wherein at least one of said mount frame and said face plate is formed with a recess at a mating surface therebetween, said recess being adapted to receive a jig for disengaging said face plate from said mount frame.
21. A wiring device having the terminal structure of claim 1, wherein a face plate is placed over said housing and is formed with a plurality of studs which extend from a rear surface of said face plate for engagement into corresponding catches in said housing.
22. A wiring device substantially as hereinbefore described with reference to the accompanying drawings.