GB2134723A

GB2134723A - Mounting push-in electricity supply devices

Info

Publication number: GB2134723A
Application number: GB08303272A
Authority: GB
Inventors: Long-River Lee
Original assignee: LEE LONG RIVER
Current assignee: LEE LONG RIVER
Priority date: 1983-02-07
Filing date: 1983-02-07
Publication date: 1984-08-15
Also published as: GB2134723B; GB8303272D0

Abstract

Electricity supply devices have a housing, comprising a panel 11 and a base plate 12 having an aperture through which a push-in electrical unit (e.g. a switch 2 or a power outlet 3) is inserted prior to location in a box 13', 13'' for connection to an electricity supply. The unit may be retained in the box by resilient lugs 242 which are moved inwardly on insertion and which can be moved inwardly when required to be removed by moving a push-key 91, 91' of control frame 9, 9' so that sloping edges 92' cooperate with the lugs 242. <IMAGE>

Description

SPECIFICATION Electricity supply devices This invention relates to electricity supply devices. Safety and practicability are two major factors to be considered for wall switches and power outlets. Taking repairs, a switch or outlet cannot usually be repaired or replaced before cutting off the main power supply. As a result, the power supply for other loads in the circuit will be interrupted. In that case, the power supply for the illuminating equipment will also usually be .interrupted and so any repair or replacing work would be very difficult to do during hours of darkness. In a conventional switch or outlet, when a switch or outlet is faulty, the whole base plate is often replaced and the rest of the switch or outlet in satisfactory condition will be wasted.After repeated repair, the base plate or the threads of the screws may be damaged so that the whole base plate is unable to be secured properly and it may be able to fall off its support.

In some newer conventional switches or outlets, a switch or outlet on a common base plate or base frame may be replaced by removing a panel. Since the power is directly connected to the switch or the outlet, the power supply has to be cut off and the power supply wire has to be removed before working on the back of the base plate to dismount the switch or outlet safely.

Thus, although the aforesaid conventional wall switch and outlet may be able to prevent electric shock because they are unable or difficult to be singly removed, this may also present disadvantages during repair.

It is a main object of the invention to overcome the aforesaid drawbacks.

According to the invention I propose an electricity supply device comprising one or more push-in electrical units each for location in each of one or more boxes for connection to an electricity supply each inserted via a respective one of one or more apertures in a panel and a base plate fastened together with control means therebetween for selectively releasing the electrical unit from the box.

According to this invention I also propose a push-in electrical unit for location in a power outlet housing and including a cover and a rear portion which houses contact means and has four external, resilient lugs, which are each confined in each of one of four channels on the outside of the cover upon insertion of the unit into the box and released after insertion to contact abutment means so as to engage the electrical unit in the box.

The push-in electrical unit may be in the form of a switch or an outlet or the like.

After simple wiring and working, a push-in switch or an outlet unit may respectively be inserted into a power outlet assembly having only one box or one of several boxes in a power outlet assembly. In other words, any required arrangement is possible and all the push-in units are interchangeable prior to wiring in so as to provide installers with more flexibility and choise.

Once the push-in switch unit and/or outlet units are inserted into the boxes they are fitted into these and the interchangeability will be lost, to ensure safety.

Under normal contact conditions, there are two retaining functions between the push-in unit and the power outlet assembly for sure fastening. The push-in unit will not spring just by being touched accidentally e.g. by a child.

In the case of a push-in unit being out of order, the unit may be sprung out by simple manipulation without using any tools, so as to replace it with a new one or to repair it as necessary.

Either the push-in switch unit or the push-in outlet unit can be provided with two fuse slots respectively for storing two fuse elements, of which one fuse element is used for providing protection function, while the other fuse is a spare one.

The power unit assembly may be furnished as protection against stealing and electrical shocks with fastening means from the rear of the assembly. Upon removing the screws on the panel of the power outlet assembly, the fastening means e.g. a thumbtack pin will easily be removed when required to restore the removable nature of the push-in unit so as to conduct repair or replacement.

An embodiment of this invention is described by way of example, with reference to the drawings, in which; Figure 1 is a perspective view of a wall switch and wall outlet according to the present invention; Figure 2 is a perspective view, seen from the rear, of the device shown in Figure 1, in which one corner of the power outlet assembly is broken away to expose part of the push-in switch unit; Figure 3 is an exploded view of a "common" box employed in the present invention, wherein the box and one spring contact are partly broken away to expose the interior; Figure 4 is an exploded view of the push-in switch unit shown in Figure 1; Figure 5 is an exploded view of the spring contact assembly shown in Figure 4; Figure 6a is a perspective view from the rear of the cover and the switch button of the push-in switch unit shown in Figure 4;; Figure 6b is a perspective view of the spring contact assembly and the rear portion shown in Figure 4, in which a lug is partly cut away; Figure 7 is a rear perspective view of the pushin switch unit shown in Figure 1; Figure 8 is an exploded view of the push-in unit shown in Figure 1; Figure 9 is an exploded view of the socket contact assembly shown in Figure 8; Figure 1 Oa is a perspective view from the rear of the lid shown in Figure 8:: Figure lOb is a perspective view of the socket contact assembly and the rear portion shown in Figure 8, in which one lug partly cut away; Figure 11 is a perspective view from the rear of the push-in outlet shown in Figure 1; Figure 12 is a partial sectional view taken along section line B-B of Figure 2 looking in the direction of the arrows; Figure 1 3 is a partial sectional view taken along line A-A of Figure 2 looking in the direction of the arrows; Figure 14 is a perspective view of the power outlet assembly with the panel partly broken away to expose control frames therein; Figure 1 5 is a perspective view of the power outlet assembly with the panel removed;; Figure 1 6 shows three schematic diagrams illustrating the relationship between the movable latch and the control frame shown in Figure 14; Figure 1 7 is a schematic diagram illustrating an installed push-in switch unit; Figure 18 is a partial exploded view of the wall switch and the wall outlet shown in Figure 1, in which the push-in switch unit has been taken out, and a portion of the panel beside the push-in outlet has been broken away to show the lug of the push-in outlet unit under the panel; Figure 1 9 is a schematic diagram illustrating removal of the push-in switch unit; and Figure 20 is a schematic exploded diagram illustrating a protective mechanism on the base plate of the power outlet assembly shown in Figure 14.

Referring to Figure 1 and Figure 2, there is shown an embodiment of the present invention, in which a power outlet assembly 1 houses a push-in switch unit 2 and a push-in outlet unit 3.

The power outlet assembly 1 includes a panel 11 and a base plate 12 fixed together. Two boxes 13', 13" are located behind the base plate 12, of which one is for the push-in switch unit 2 and the other is for the push-in outlet unit 3. One the panel 11 , there are two rectangular apertures 111 for the push-in units 2 and 3 to pass through, two apertures 1 12 for the push keys 91 and 91' of control frames (sandwiched between the panel 11 and the base plate 12; shown in Figure 14) to project outwardly, and another aperture 1 13 for the head of the movable latch 10 to project outwardly. Two screw holes 1 4 are used for fixing the power outlet assembly 1 to the wall box with screws.The panel 11 and the base plate 12 may be fixed together by applying an adhesive between their edges or by any other method to prevent the parts (such as the control frame and movable latch) between the panel 11 and the base plate 12 from falling out during removal the power outlet assembly 1 on loosening the screws.

Before installing the push-in units 2 and 3 for the first time, the switch box 1 3' and the outlet box 13" may have a substantially identical structure based on one kind of box, here termed the "common" box 13 as shown in Figure 3.

Referring to Figure 2, there are shown four holes 1 31 in the four corners of the rear faces of the boxes 13' and 13", being used as the inserting holes for the power supply wires 4 (partly shown).

In the middle of the rear face of each box is a shallow hole 132 provided for installing a conical spring 5. Referring to Figure 3, there are shown two spring contacts 6 and 7 and another spring contact pair 8 being installed in the four corners inside the common box 13. In fact, the spring contact pair 8 is formed by a connection to two spring contacts which are identical with the spring contacts 6 and 7. An insulating piece 133 is used to separate and to fix the spring contacts 6 and 7, while another piece 134 projects from the rear face of the box for fixing the spring contact pair 8.

Referring to Figure 3, four slanting pegs 135 (only one being shown) on the rear of the box are used for fixing the spring contacts 6, 7 and 8.

Further, the spring contacts 6, 7 and 8 may be further fixed by means of feet 611,711 (shown in Figures 2 and 3), 811 and 811' (shown in Figure 2) which each pass through each of four apertures 136 (only one is shown) in the rear face and are then bent into four notches in the rear face.

The spring contacts 6, 7 and the spring contact pair 8 each have at least one outer leaf spring and one inner leaf spring. Each outer leaf spring can at least provide one contact point to contact with the corresponding spring contact on the push-in unit 2 or 3. For example, in Figure 3, the spring contact pair 8 includes a longer outer leaf spring 81 and two inner leaf springs 82, 82' at the both ends of the outer leaf spring 81. The spring contacts 6 and 7 comprise two outer springs 61, 71 and two inner springs 62, 72 respectively.

Each of the inner leaf springs 62, 72, 82 and 82' is a bent leaf spring with one extending out of the opening of the outer leaf spring.

Referring to Figure 3, there is shown the outer leaf spring 81 of the spring contact pair 8 having two contacts 81 2 and 812' bent downwards so as to contact with corresponding contacts of the push-in unit 2 or 3.

Referring to Figures 2 and 3 and taking the spring contact pair 8 for example, the power supply wire 4 is inserted in to the hole 131, and is fastened between the inner leaf spring 82 and the outer leaf spring 81. By means of the elastic force of the extended end of the inner spring 82, the bare portion of the wire out of the outer leaf spring 81 is fastened firmly so that the power supply wire 4 is almost unable to be pulled out once inserted. Further, beside the position where the extended end of each of the inner leaf spring extends out, a window 138 is provided for pulling out the power supply wire 4, if necessary, by using a screwdriver to penetrate therethrough and to push aside and hold the inner leaf spring.

Referring to Figure 4, there is shown the pushin switch unit 2, which includes a cover 22 for mounting the switch button 21 and a rear portion 24 for housing the spring contact assembly 23. At the rear of top cover 22, there are two hooks 221, which are to be hooked together with the two grooves 241 on the rear portion 24 respectively. On each of the two opposite sides of the top cover 22, there are two channels 222 which can be dovetailed with two corresponding lugs 242 of the rear portion. Each lug 242 extends from the rear face of the rear portion 24 toward the top cover 22 at a suitable given angle so as to allow elasticity. Upon the lugs 242 being pressed inwards, they will be completely tucked into the corresponding channels 222.

Referring to Figure 4 and 5, there is shown a spring contact assembly 23 including one movable spring contact 231 and two fixed spring contacts 232, 233 which form a double-throw switch, and one fixed leaf spring 234 that connects the movable spring contact 231 to the outside of the rear of the base 24.

Referring to Figure 6, the movable spring contact 231 may be actuated by means of its movable end being engaged with the notch 211 at the bottom of the switch button 21.

The fixed spring contacts 232 and 233 each have a foot bent downwardly as shown in Figure 6(b). Referring to Figure 7, there is shown the foot of the movable spring contact 231 passing through the rear face of the rear portion 24 and extending into one of the two fuse slots on the bottom of the base 24. Through the fuse element 25 stored in this fuse slot, the foot of the movable spring contact can connect electrically with the foot of the fixed leaf spring 234 at the other end of the fuse, while a spare fuse element 25' is stored in the other fuse slot which has no metallic contact with any spring contacts. Two ribbons 26 and 26' each have an end fixed in the two fuse slots for the purpose of removing the fuse element 25, 25' easily.Between the two fuse slots, a conical hole 244 is provided in the rear face of for engaging with the top of the conical spring 5 shown in Figures 2 and 3 upon the push in switch unit 2 being inserted into the switch box 13'.

Referring to Figure 4, there are shown a guide groove 245 on one side of the rear portion 24, and a small groove 246 on the opposite side of the rear portion. Referring back to Figure 3, there are shown a guide rail 1 39 corresponding to the guide groove 245 and upper and lower locating members 13a, 13b inside the box 13, wherein the upper locating member 1 3a is at the position corresponding to the small groove 246.

Upon installing the wall switch in the working site, the lower member 1 3b is cut off (e.g. with a pair of pliers). Then, the push-in switch unit 2 is inserted into the box along the guide rail 139 and the upper locating member 13a. After being inserted, the two fixed spring contacts 232 and 233 of the push-in switch unit 2 will directly contact with the spring contacts 6 and 7 in the box 13' respectively. Also, the movable spring contact 231 of the switch unit 2 will indirectly contact with the spring contact pair 8 in the box 13' by means of the fuse 25 and the fixed leaf spring 234, as shown in Figure 2.In other words, the common box 1 3 shown in Figure 3 may be used as the switch box 13' shown in Figure 2 when adapted by the lower locating member 1 3b being removed, Referring to Figures 8 and 11, there is shown the push-in outlet unit 3, which includes a lid 31 and a rear portion 33 to be installed in the socket contact assembly 32. The lid 31 has two hooks 311 which are identical to the hooks 221 of the cover 22 of the push-in switch unit 2. The rear portion 33 is similar to the rear portion 24 of the push-in switch unit 2 except that an insulating piece 331 is installed therein to insulate the two socket contacts 321 and 322, and the outer left side groove 332 corresponds to the lower locating member 1 3b in the common box 1 3 shown in Figure 3.The base 33 also has four symmetrically disposed lugs 333. The socket contact 321 has two feet bent between the bottom and the outside of the rear portion 33, as shown in Figure 1 Ob. And another socket contact 322 has a foot passing through the rear face of the rear portion 33, appearing at one end of a fuse slot in the rear face so as to come into contact with the fuse element 25 stored in that fuse slot, as shown in Figure 11. The two feet of the fixed leaf spring 323 are bent over in the opposite position of the feet of the socket contact 321, and one of the feet appears at the other end of the fuse slot, having metallic contact with the fuse element 25.

Therefore, with the upper locating member 1 3a in the common box 1 3 (shown in Figure 3) removed, the push-in outlet unit 3 shown in Figure 11 may be inserted into the box as shown in Figure 12 so as to have the feet of the socket contact 321 directly in contact with the spring contacts 6 and 7 in the box 13", and to have another socket contact 322 indirectly contacted with the spring contact pair 8 by means of the fuse element 25 and the fixed leaf spring 323, as shown in Figure 13. In other words, once the upper locating member 1 3a inside the common box 13 shown in Figure 3 is removed, the common box may be used as the outlet box 13" shown in Figure 2.

The first function of the fixed leaf spring 234 in the push-in switch unit 2 and the fixed leaf spring 323 in the push-in outlet unit 3 is, by means of the fuse 25, to connect one terminal of the power supply to the movable spring contact 231 and the socket contact 322 respectively. The second function of the fixed leaf spring 234 or 323 is to provide extra contact by means of one of its two feet, together with the spring contact pair 8 inside the box 13' or 1 3", so as to transmit the power supply at one terminal incoming from a given spring contact in a box to the rest switch box or outlet box. Referring back to Figure 2, there is shown the power supply wire 4 connecting the switch box 13' and the outlet box 13".

The locating member 1 3a and 1 3b may be made thin (e.g. under 1 mm) so as to be cut off easily and preventing the push-in unit 2 or 3 from being inserted into the wrong box. In other words, it will assure the correct insertion for safety's sake. During the first installation, even if the bottom of the locating members 1 3a or 1 3b is not cut off clearly, it will not affect the insertion because the push-in units 2 and 3 include respectively rear portions 24 and 33 tapering off slightly toward the bottom.

Thus, the push-in switch unit 2 and the push-in outlet units 3 are interchangeable during installation (i.e. the box 1 3 is adaptable to either the push-in unit 2 or 3) so as to provide the electrical engineer or the electrician with considerable flexibility. However, once the installation is done, the interchangeable feature will be removed so as to assure safety.

Referring to Figure 14, there are shown two control frames 9 and 9' sandwiched between the panel 11 and the base plate 1 2 of the power outlet assembly 1. Each of the frames 9 and 9' has, at one end, one push key 91 and 91' projecting out of the aperture 112 on the panel 11 as shown in Figure 1 so as to facilitate operation. Along the edges of the windows of the control frames 9 and 9', four symmetrically disposed recesses having a slanting edge 92 and 92' are furnished respectively, so that the space between two opposed recesses 92 and 92' is wider than that of the aperture 111 on the panel 11.

Referring to Figure 15, there are shown two projecting guide rails 122 at both sides of each opening 121 on the base plate 1 2 for positioning each of the control frames 9 and 9'. The two rails 122 between the two openings 121 are each divided by a groove 1 23 into a lower portion and an upper portion. The lower portions are connected at the top and the upper portions are also connected with the result that a slot 124 is formed. Figure 1 5 also shows the marks (shown with dotted line) left by removing the locating members 1 3a or 1 3b upon modifying a common box 13 into a switch box 13' or an outlet box 13".

Referring to Figure 14, there is shown a movable latch 10 furnished in the groove 123.

The head of the movable latch 10 extends out of the aperture 113, as shown in Figure 1, so that the movable latch 10 can be moved laterally. In the slot 124, a small rubber roller 20 having a diameter bigger than the depth of the slot is fitted to press against the movable latch 10 in a stationary condition so as to have the latch always maintained in the central position unable to move freely, no matter how the power outlet assembly 1 is installed (horizontally or vertically) in a wall box on the wall.

Referring to Figure 14 and 16a, the two control frames 9 and 9' each have a slot 93 and 93' adjacent both ends of the movable latch 1 0, so that the ends of the movable latch 10 are entered into the slots 93 and 93' a little way respectively under the aforesaid stationary condition. Under this condition, pressure applied to any one of the push keys 91 and 91' in a direction toward the bow springs 1 5 and 15', will be prevented from moving the control frames 9 and 9' downwards along the rails 122.

Referring to Figure 16b, there is shown a schematic diagram in which the movable latch 10 has been removed toward the slot 93. Under this condition, the control frame 9' can be moved downwards as shown in Figure 16c, and will be moved back to its original position with the force of the bow spring 1 5' upon the pressure being removed.

Since the width of the aperture 121 of the base plate 12 is slightly bigger than that of the aperture 111 of the panel 11 (referring to Figure 1 2 and 15, and assuming that the push-in outlet unit 3 shown in Figure 12 is a push-in switch unit 2), and since the positions of the four resilient lugs 242 on the push-in switch unit 2 exactly correspond to the four slanting recesses 92 on the control frame 9 as shown in Figure 1 7 upon insertion of push-in switch unit 2 into the switch box 13' through the panel aperture 111, the four lugs 242 will be pressed gradually through the edges of the aperture 111 until the lugs 242 are behind the panel 11 upon the push-in switch unit 2 being fully inserted into the box 13', the four lugs 242 will spring out immediately with their free ends being caught behind the panel 11 so as to have the push-in switch unit 2 fixed in the box 13', without being forced out by the conical spring 5 on the rear face of the box.

The aforesaid applies similarly to the push-in outlet unit 3. Referring to Figure 12 and 18, there is shown the lugs 333 of the push-in outlet 3 caught under the panel 11. Referring to Figures 3 and 18, the four sloping pieces 1 35 (partly shown) in both the switch box 13' and the outlet 13" have fixing function to the push-in unit 2 and 3 because, upon the push-in units 2 and 3 being inserted respectively into the boxes 13' and 13", their rear portions 24 and 33 will be exactly located between the four sloping pegs 1 35.

As mentioned above, when the movable latch 10 is positioned in the central position, the control frames 9 and 9' are stopped by the movable latch 10 and are unable to be moved.

The control frame 9 and 9' can thus prevent the relevant push-in units 2 and 3 respectively from being taken out directly. Therefore, each of the push-in units 2 and 3 has two latching means for better fixing so as to prevent it from springing out e.g. upon being touched accidentally or being played with by a child.

Referring to Figure 18, there is shown the movable latch 10 moved to the outlet side. When pressure is applied to the push key 91 the control is moved downwardly against the bow springs 1 5 so as to have the four lugs 242 pressed by the slanting edges 92 into the four small channels 222 (shown in Figure 4) of the cover 22, as shown in Figure 19, the lugs 242 are not caught by the panel 11, and the push-in switch unit 2 may be taken out under the influence of the conical spring 5 in the rear of the box 1 3'. By the same token, if the movable latch 10 is moved to the switch side, and the push key 91' is pushed downwards, the push-in outlet unit 3 can be removed.

Should protection against stealing or electrical shocks be important (for example, in a lobby, a public stair-way, and a public hall), the present invention has a special tamper-proof feature, which is described, by referring to Figures 1 and 20, as follows: Referring to Figure 20, there is shown a schematic diagram in which a shallow hole 125 is furnished in the back of the base plate 12 opposite to the movable latch 10. In the centre of the shallow round hole 125, there is a small through hole 126. The shallow hole 125 is used for fitting a thumb-tack pin 30 that passes through the small through hole 126 and the small hole 101 on the bottom of the movable latch 10.

The thumb-tack pin 30 will prevent the movable latch 10 from moving, thus preventing the push-in units 2 and 3 from being removed. In case of faults in the assembly the screws are removed from the screw holes 14 on the panel 11, and the thumb-tack pin 30 is removed from the slot over the shallow hole 1 25. Then, the aforesaid procedures are followed to remove the push-in units 2 and 3. If such protection is not necessary the thumb-tack pin 30 may be removed upon installing the power outlet assembly 1.

Since the common box 1 3 is adaptable to both the push-in switch unit 2 and the push-in outlet unit 3 during installation, a power outlet assembly 1 with one or more than one common boxes 13 may, matching with the push-in unit(s), provide one or more than one wall switch or wall outlet, or provide same number of wall switch(es) and wall outlet(s) after the first installation. When a power outlet assembly 1 contains "N" (N > 1) boxes arranged next to each other, "N-1" movbale latches 10 may be provided, each of them to be installed between two conical frames.

When a power outlet assembly 1 includes only one box, one movable latch 10 should be installed. In case of the "N" boxes not being arranged next to each other, the number of the movable latches 10 may be determined in accordance with the arrangement of the individual case.

It will be apparent that various arrangement employing the apparatus herein described may be made which fall within the scope of the claims.

Claims

1. An electricity supply device comprising one or more push-in electrical units each for location in each of one or more boxes for connection to an electricity supply each box inserted via a respective one of one or more apertures in a panel and a base plate fastened together with control means therebetween for selectively releasing the electrical unit from the box.

2. An electricity supply device according to claim 1, wherein the push-in electrical unit includes a cover and a rear portion which houses contact means and has four external, resilient lugs, which are each confined in each of one of four channels on the outside of the cover upon insertion of the unit into the box and released after insertion to contact abutment means so as to engage the electrical unit in the box.

3. An electricity supply device according to claim 2, wherein the push-in electrical unit further includes guide means cooperable with guide means on the box to further locate the unit in the box and to ensure cooperation of the electrical contacts of the box and the unit.

4. An electricity supply device according to any one of claims 1, 2 or 3, wherein the control means comprises a manually movable stop cooperable with a control frame, which is located between the panel and the base plate and which is slidable by manual means on guide means on the base plate from a first position to a second position so as to selectively allow or prevent movement of the control frame and release or retention of the push-in electrical unit from the box.

5. An electricity supply device according to claim 4, wherein the or each aperture comprises a first aperture in the panel face-to-face with a second aperture in the base plate and the first aperture is smaller than the second and wherein the control frame has an aperture face-to-face with the first and second apertures in a peripheral member, the internal edge of which has four recesses, in positions corresponding to the positions of the resilient lugs of the electrical unit and having sloping edges cooperable with the stationary lugs on manually sliding control frame along the guide means from the first position to the second position so that the resilient lugs are movable into the channels on the cover of the electrical unit and the electrical unit can be removed from the box.

6. An electricity supply device according to claim 4 or 5, with a spring for returning the control frame from the second position to the first position.

7. An electricity supply device according to any preceding claim, wherein the box for receiving the electrical unit includes a spring for urging the electrical unit out of the box and internal guide means for cooperating with the electrical unit so as to locate the electrical unit in the box.

8. An electricity supply device according to claim 7, wherein the guide means of the box includes a locating member selectable from a pair of locating members of which each is adapted to be employed for either an electrical switch unit or an electrical power outlet unit and the unwanted locating member is removable, so as to allow the same box to be adapted for either an electrical switch unit or an electrical power outlet unit.

9. An electricity supply device according to any preceding claim, wherein the box houses contact means comprising two discrete spring contacts and a spring contact pair mounted at the four corners, the spring contact pair including two spring contacts, which are identical to the discrete spring contacts, connected each other along an inner surface of the box, the spring contacts each having a foot extending out of the box and bent over onto a notch on the outside of the box.

1 0. An electricity supply device according to any preceding claim, wherein the push-in electrical unit is a switch, the cover housing a switch button and wherein the contact means comprises a movable spring contact having a foot extending out of the rear face of the rear portion and disposed at one end of a fuse slot in the rear face, a fixed leaf spring having two feet projecting from the rear face and bent to be disposed at the other end of the fuse slot so as to connect electrically with the foot of the movable spring contact by means of a fuse element therebetween, and two fixed spring contacts each having a foot projecting out of the rear face.

11. An electricity supply device according to claim 10, wherein the rear portion has a guide channel on its one outer surface dovetail correspondingly to a guide rail inside the switch box and a guide groove dovetailed correspondingly to a rail inside the switch box so as to permit the push-in switch unit being inserted into the switch box and to have the two feet of the fixed spring contacts come into contact with the two discrete spring contacts mounted in the rear face of the rear portion and simultaneously to have the two feet of the fixed leaf spring come into contact with the spring contact pair mounted thereon.

1 2. A electricity supply device according any preceding claim, wherein the push-in electrical unit is a power outlet, the cover having means to accommodate the pins of a plug and the rear portion housing a pair of socket contacts and a fixed leaf spring, wherein the first socket contact has a foot extending out of the rear face of the rear portion and disposed at one end of a fuse slot in the rear face and the fixed leaf spring has two feet projecting from the face being bent as to be disposed at the other end of the fuse slot so as to connect electrically with the foot of the first socket contact by means of a fuse element therebetween and the second socket contact has two feet projecting out of the rear face.

1 3. An electricity supply device according to claim 12, wherein the rear portion has a guide channel on its one outer surface dovetailed correspondingly to a guide rail inside the outlet box and a guide groove dovetailed correspondingly to a rail inside the outlet box so as to permit the push-in outlet unit being inserted into the outlet box and to have the two feet of the second socket contact come into contact with the two discrete spring contacts mounted in the rear face of the rear portion of the outlet box, and simultaneously to have the two feet of the fixed leaf spring come into contact with the spring contact pair mounted thereon.

14. An electricity supply device according to any preceding claim, wherein the base plate further includes means for fastening the movable stop for preventing it from being moved along the groove on the base plate.

1 5. A push-in electrical unit for location in a power outlet housing and including a cover and a rear portion which houses contact means and has four external, resilient lugs, which are each confined in each of one of four channels on the outside of the cover upon insertion of the unit into the box and released after insertion to contact abutment means so as to engage the electrical unit in the box.

1 6. A push-in electrical unit, according to claim 15, wherein the push-in electrical unit is a switch, the cover housing a switch button and wherein the contact means comprises a movable spring contact having a foot extending out of the rear face of the rear portion and disposed at one end of a fuse slot in the rear face, a fixed leaf spring having two feet projecting from the rear face bottom and bent to be disposed at the other end of the fuse slot so as to connect electrically with the foot of the movable spring contact by means of a fuse element therebetween, and two fixed spring contacts each having a foot projecting out of the rear face.

1 7. A push-in electrical unit according to claim 16, wherein the rear portion has a guide channel on its one outer surface dovetail correspondingly to a guide rail inside the switch box and a guide groove dovetailed corresponding to a rail inside the switch box so as to permit the push-in switch unit being inserted into the switch box and to have the two feet of the fixed spring contacts come into contact with the two discrete spring contacts mounted in the rear face of the rear portion and simultaneously to have the two feet of the fixed leaf spring come into contact with the spring contact pair mounted thereon.

1 8. A push-in electrical unit according to claim 17, wherein the push-in electrical unit is a power outlet, the cover having means to accommodate the pins of a plug and the rear portion housing a pair of sockets contacts and a fixed leaf spring, wherein the first socket contact has a foot extending out of the rear face of the rear portion and disposed at the other end of a fuse slot in the rear face and the fixed leaf spring has two feet projecting from the rear face being bent as to be disposed at the other end of the fuse slot so as to connect electrically with the foot of the first socket contact by means of a fuse element therebetween and the second socket contact has two feet projecting out of the rear face.

19. A push-in electrical unit according to claim 18, wherein the rear portion has a guide channel on its one outer surface dovetailed correspondingly to a guide rail inside the outlet box and a guide groove dovetailed correspondingly to a rail inside the outlet box so as to permit the push-in outlet unit being inserted into the outlet box and to have the two feet of the second socket contact come into contact with the two discrete spring contacts mounted in the rear face of the rear portion of the outlet box, and simultaneously to have the two feet of the fixed leaf spring come into contact with the spring contact pair mounted thereon.

20. An electricity supply device constructed and arranged substantially as herein described with reference to any of the Figures of the drawings.

21. A push-in electrical unit constructed and arranged substantially as herein described with reference to any of the Figures of the drawings.