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Title:
ELECTRICAL SOCKET
Document Type and Number:
WIPO Patent Application WO/2005/025012
Kind Code:
A1
Abstract:
An electrical socket (20) selectively receives a first plug pin configuration and a second plug pin configuration. The socket includes an electrical terminal receptacle (31) moveable within a body (21) between a first position for operably receiving the first plug pin configuration and a second position for operably receiving the second plug pin configuration. The receptacle (31) is releasably retained in the first position while no plug is inserted in the socket.

Inventors:
PABARI ALPHA SHANTILAL (GB)
PABARI HITEN SHANTILAL (GB)
Application Number:
PCT/GB2004/003783
Publication Date:
March 17, 2005
Filing Date:
September 03, 2004
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
PABARI ALPHA SHANTILAL (GB)
PABARI HITEN SHANTILAL (GB)
International Classes:
H01R13/453; H01R27/00; H01R31/06; (IPC1-7): H01R27/00; H01R13/453; H01R31/06
Domestic Patent References:
WO1993014540A11993-07-22
Foreign References:
US5885109A1999-03-23
US5758414A1998-06-02
US6247941B12001-06-19
US20030064630A12003-04-03
GB2326775A1998-12-30
US4518212A1985-05-21
US5641292A1997-06-24
Attorney, Agent or Firm:
Molyneaux, Martyn W. (40-43 Chancery Lane, London WC2A 1JA, GB)
Download PDF:
Claims:
CLAIMS
1. An electrical socket (20) for selectively receiving a first plug pin configuration and a second plug pin configuration, the socket comprising: a body (21), an electrical terminal receptacle (31) moveable within the body between a first position for operably receiving the first plug pin configuration and a second position for operably receiving the second plug pin configuration; and first retaining means (39) for releasably retaining the receptacle in the first position.
2. An electrical socket as claimed in claim 1, wherein the body includes a housing (22) within which the receptacle (31) is moveable between the first position and the second position.
3. An electrical socket as claimed in claims 1 or 2, wherein the first retaining means is latching means comprising shutter means (39) for shuttering pin receiving apertures of the receptacle such that inserting pins of a plug of the second pin configuration in the apertures unlatches the receptacle from the first position for movement to the second position.
4. An electrical socket as claimed in any of claims 1 to 3, wherein the shutter means (39) include cam means (391,392) for cooperation with the inserted pins of the second pin configuration whereby actuation of the cam means by the inserted pins cause shutters, otherwise preventing insertion of the pins, to open.
5. An electrical socket as claimed in any of the preceding claims, wherein the electrical socket further includes connector means (93,94, 95) for receiving electrical wiring from an electricity power supply for providing electrical connection to respective terminals in the electrical terminal receptacle at least at the first position for the first pin configuration and the second position for the second pin configuration.
6. An electrical socket as claimed in any of the preceding claims, wherein the first retaining means is a rotatable ring means (91) for engaging the receptacle when the ring means is in a first rotational position and releasing the receptacle when the ring means is in a second rotational position.
7. An electrical socket as claimed in any of the preceding claims, wherein second retaining means are provided for retaining the receptacle in the second position.
8. An electrical socket as claimed in any of the preceding claims, wherein there is provided releasing means operable by manually operable pushbutton means (71) for releasing the receptacle from the second position for movement to the first position.
9. An electrical socket as claimed in any of the preceding claims, wherein the second position is a recessed position and the body further includes a swipe electrical terminal (676) for receiving a plug having a peripheral swipe electrical connector.
10. An electrical socket as claimed in any of the preceding claims, wherein the body further includes biasing means (50) for biasing the receptacle (31) towards the first position.
Description:
ELECTRICAL SOCKET This invention relates to an electrical socket.

Adaptors for electrical plug sockets, to allow the use of plugs of more than one pin configuration in a same socket, are known. They are of particular use for travellers travelling between countries using different pin configurations. However, it is inconvenient for a traveller to carry such an adaptor for each device the traveller wishes to use, or for a traveller's host establishment to supply the traveller with appropriate adaptors. Moreover, travel adaptors are bulky in use and the combined weight of the plug and adaptor may cause the adaptor and plug combination to disengage from a socket.

It is an object of the present invention to at least ameliorate the aforesaid deficiencies in the prior art.

According to the present invention there is provided an electrical socket for selectively receiving a first plug pin configuration and a second plug pin configuration, the socket comprising: a body, an electrical terminal receptacle moveable within the body between a first position for operably receiving the first plug pin configuration and a second position for operably receiving the second plug pin configuration; and first retaining means for releasably retaining the receptacle in the first position.

Preferably, the body includes a housing within which the receptacle is moveable between the first position and the second position.

Conveniently, the first retaining means is latching means comprising shutter means for shuttering pin-receiving apertures of the receptacle such that inserting pins of a plug of the second pin configuration in the apertures unlatches the receptacle from the first position for movement to the second position.

Advantageously, the shutter means include cam means for cooperation with the inserted pins of the second pin configuration whereby actuation of the cam means by the inserted pins cause shutters, otherwise preventing insertion of the pins, to open.

Advantageously, the electrical socket further includes connector means for receiving electrical wiring from an electricity power supply for providing electrical connection to respective terminals in the electrical terminal receptacle at least at the

first position for the first pin configuration and the second position for the second pin configuration.

Alternatively, the first retaining means is a rotatable ring means for engaging the receptacle when the ring means is in a first rotational position and releasing the receptacle when the ring means is in a second rotational position.

Advantageously, second retaining means are provided for retaining the receptacle in the second position.

Conveniently, there is provided releasing means operable by manually operable pushbutton means for releasing the receptacle from the second position for movement to the first position.

Advantageously, the second position is a recessed position and the body further includes a swipe electrical terminal for receiving a plug having a peripheral swipe electrical connector.

Conveniently, the body further includes biasing means for biasing the receptacle towards the first position.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is an exploded front perspective view of a first embodiment of a socket according to this invention; Figure 2 is an enlarged view of a first embodiment of an electrical terminal receptacle body of the socket of Figure 1; Figure 3 is a cut-away rear perspective view of the socket of Figure 1, with some internal features and components omitted for clarity, with the electrical terminal receptacle of the socket latched in an operable position for a first pin configuration; Figure 4 is the cut-away rear perspective view of the socket of Figure 3, with the receptacle of the socket unlatched in the operable position for the first pin configuration; Figure 5 is the cut-away rear perspective view of the socket of Figure 3, with the receptacle of the socket in an operable position for a second pin configuration of connectors;

Figure 6 is a front perspective view of the socket of Figure 1 with the receptacle in an operable position for the first pin configuration; Figure 7 is a front perspective view of the socket of Figure 1 with the receptacle in an operable position for the second pin configuration; Figure 8 is a front perspective view of a second embodiment of a socket according to the invention, with an electrical terminal receptacle in a first position for the first pin configuration; Figure 9 is the front perspective view of the embodiment of Figure 8 with the receptacle in a recessed second position for the second pin configuration; Figure 10 is a front perspective view of a third embodiment of a socket according to the invention, with an electrical terminal receptacle in a first position for the first pin configuration; Figure 11 is the front perspective view of the third embodiment of Figure 10 with the receptacle in a recessed second position for the second pin configuration; Figure 12 is an exploded front perspective view of a fourth embodiment of a socket according to this invention; Figure 13 is an enlarged view of a further embodiment of a terminal receptacle and of a socket housing of Figure 12; Figure 14 is an enlarged view of the connector block of Figure 12; Figure 15 is an enlarged view of the further electrical terminal receptacle body of the socket of Figure 12; and Figure 16 is an enlarged view of the connector block housing of the socket of Figure 12.

In the Figures like reference numerals denote like parts.

Referring to Figures 1 to 7, an electrical plug socket 10 has a body 20 and an electrical terminal receptacle 30 moveable along a longitudinal axis 11 within the body 20. The body 20 has a faceplate 21 and a right circular cylindrical housing 22 central of, and opening into, the faceplate, the housing having the axis 11 substantially perpendicular to major faces of the faceplate and being located on a rear side of the faceplate 21. As orientated in the Figures 1-7, an inner surface of the cylindrical housing 22 is provided with opposed substantially vertical first and second planar

faces 221,222, the substantially vertical planar faces 221,222 extending from a rear of the housing to a location proximate a front of the housing. The vertical first and second planar faces 221,222 of the housing are separated by substantially horizontal first and second elongate slots 223,224 respectively, extending, parallel to the housing longitudinal axis, from a front end of the planar faces to a position proximate a rear end of the planar faces such that the slots are open at the front of the housing 22 and closed at the rear of the housing 22. As shown in Figures 3 to 5, the inner surface of the housing 22 has opposed top and bottom electrically conducting elongate earth potential strips 226,227 respectively, radially extending inwards from the inner surface of the housing and parallel to the housing longitudinal axis 11 from the rear of the housing to the front of the housing, the strips being interconnected by a diametrically extending earth potential strip 225. At least one electrical connector, not shown, is provided for electrically connecting an earthing potential wire to the elongate earth potential strips 226,227.

As orientated in the Figures 1-7, the receptacle 30 includes a cylindrical, open- ended receptacle body 31, best seen in Figure 2, having on an outer cylindrical surface opposed substantially vertical receptacle faces 321,322 divided substantially horizontally by elongate radially outwardly extending rectangular projections 323, 324, parallel to a longitudinal axis of the cylindrical receptacle body 31, for sliding engagement of the vertical receptacle faces 321,322 with the vertical housing faces 221,222 respectively, and sliding engagement of the elongate rectangular projections 323,324 of the receptacle with the elongate slots 223,224 of the housing 22. The outer cylindrical surface of the receptacle body 31 is also provided with diametrically opposed top and bottom elongate slots 326,327 parallel with the longitudinal axis of the cylindrical receptacle body 31 for sliding engagement with the diametrically opposed top and bottom electrically conducting earth strips 226,227 of the housing, respectively. Therefore the receptacle body 31 may slide longitudinally in the housing 22 but is prevented from rotating with respect to the housing about the coaxial longitudinal axes of the housing and receptacle body.

Referring again to Figure 2, proximate the top elongate slot 326, the receptacle body 31 is provided on an inner surface thereof with a first elongate substantially cuboid housing 33 extending from a front to a rear of the receptacle body parallel to a longitudinal axis thereof, for receiving a rectangular cross-section earth potential connector of an electrical plug. With the receptacle assembled in the housing, the top

earth strip 226 of the housing extends through the top elongate slot 326 of the receptacle body 31 and into the first cuboid housing 33.

Proximate each of the vertical receptacle faces 321,322, but offset therefrom, the inner surface of the receptacle body 31 is provided with second and third elongate substantially cuboid housings 34,35 extending from a front to a back of the receptacle body parallel to a longitudinal axis thereof for receiving respectively first and second electrical terminals 36,37 described herein. Vertical walls of the second and third housings 34,35 and inner surfaces of the receptacle body vertical faces are reduced at a front face of the receptacle body to form cutaways 341,351, 342 to receive a first slidable shutter 38 in a manner described herein.

As shown in Figure 1, a first electrical terminal 36 has a U-shaped portion 361, having a single-turn scroll-shaped portion 362 rising from an innermost edge, in use, of an upper leg of the U-shaped portion 361. Thus, as shown in Figure 1, the scroll portion is located vertically above the U-shaped portion with the parallel legs of the U- shaped portion and a longitudinal axis of the scroll-shaped portion parallel to the coaxial longitudinal axis 11 of the receptacle and housing, such that the terminals are open at a front end thereof to receive extremities of plug pins inserted in the socket.

The second electrical terminal 37 is a mirror image of the first electrical terminal 36.

The first and second electrical terminals are of resilient electrically conducting material and sized to form a friction fit in the second and third housings 34,35 respectively. However, other means of fixing the terminals in the housings 34,35 may be used, for example by welding, moulding or an adhesive. The first and second electrical terminals are provided with electrical connectors, not shown, for connecting electricity supply wires to the terminals.

The first shutter 38 is an elongate strip of electrically insulating material disposed, as shown in the Figures, with a longitudinal axis substantially horizontal and major faces substantially vertical and perpendicular to the longitudinal axis 11 of the receptacle. The shutter is provided on a front major face proximate opposed ends thereof with cam surfaces 381,382 such that the shutter may be driven upwards by inserted pins of a plug (not shown). An upper face of the shutter is provided with a centrally located recess having a central vertical locating pin 383 for receiving a first end of a first shutter compression spring 385. In use a second end of the first shutter compression spring 385 bears on an under outer face of the first elongate housing 33

such that the shutter is slideable upwards in the cutaways 341,351, 342 of the inner walls of the second and third housings and the inner vertical faces of the receptacle body against a bias of the first shutter spring bearing on the under face of the first housing 33 and the central recess 383 of the first shutter.

The receptacle is further provided with a receptacle faceplate 40 having a same transverse cross-section as the receptacle body, except that projections 423,424 corresponding with projections 323,324 on the receptacle body have further dog-leg projections 4231,4241 for engaging a rear surface of the faceplate 21 to limit forward movement of the receptacle 30. An inner surface of the receptacle faceplate is shaped to receive a slideable U-shaped second shutter 39, orientated in a parallel plane to the first shutter 38. An upper face of a base portion of the U-shaped second shutter 39 has a chamfered central projection and an opposed lower face of the base portion has a central recess 393 for receiving a first end of a second shutter compression spring 395.

The second shutter is provided on a front major face proximate opposed ends thereof with cam surfaces 391,392 such that the shutter may be driven downwards by inserted pins of a plug. Upper ends of the legs of the U-shaped shutter are inwardly tapered to conform substantially with the outer cylindrical surface of the receptacle body when the shutter is in a lowered position and to project above the outer surface when the shutter is in a raised position. In use the second shutter is biased upwards by the second shutter spring acting on the recess 393 and on the receptacle faceplate 40.

The receptacle faceplate 40 is provided with a top rectilinear recess 43 for alignment with the first housing 33 and with the top elongate slot 326. First and second rectangular apertures 441,451 are provided for alignment with the U-shaped portions 361,371 of the electrical terminals 36,37 located in the second and third housings 34,35 respectively. The faceplate is also provided with first and second circular apertures 442,452 for alignment with the scroll-shaped portions 362,372 of the electrical terminals 36,37 located in the second and third housings 34,35 respectively. The receptacle faceplate is provided with a bottom recess 427 for alignment with the bottom elongate slot 327.

Referring to Figures 3 to 5, the housing 22 is provided with two opposed apertures 228 (only one of which is shown for clarity) proximate an inner surface of the faceplate 21 for receiving upper extremities of the legs of the U-shaped second shutter 39, when the second shutter is in an uppermost position.

Referring to Figures 1 and 3 to 5, a receptacle compression spring 50 is located axially within the housing 22 bearing on a wall, not shown in the interests of clarity, inwards of the earth potential strip 225 and an inner face of the body 31 to urge the receptacle to a location in which the dogleg projections 4231,4241 on the receptacle faceplate 40 engage a rear surface of the faceplate 21 and in which a front face of the receptacle faceplate 40 is substantially planar with a front face of the faceplate 21.

In use without a plug inserted in the socket, the receptacle 30 is urged forward by the receptacle biasing spring 50 so that a front face of the receptacle faceplate 40 is substantially coplanar with a front face of the faceplate 21. The second shutter 39 is urged upwards by the second shutter spring 395 so that extremities of the legs thereof enter the housing apertures 228 to latch the receptacle in position with respect to the housing 22 and faceplate 21. The cam surfaces 391,392 thereby close the circular apertures 442,452 respectively. Similarly, the first shutter 38 is urged downwards by the first shutter spring so that the first shutter cam surfaces 381,382 close the rectangular apertures 441, 451.

When rectangular cross-section pins of a British Standard three-pin plug having an earth and first and second current carrying pins are inserted in the apertures 43, 441,451 the earth pin engages the top electrically conducting earth potential strip 226 and extremities of the current-carrying plug pins bear on the first shutter cam surfaces 381,382 to slide the first shutter upwards, opening the shuttered rectangular apertures 441,451 allowing the current-carrying plug pins to contact the U-shaped portions 361, 371 of the terminals 36,37 by passing between the respective legs thereof.

When, alternatively, circular cross-section pins of a two-pin plug having a peripheral earth potential strip contact are inserted in the circular apertures 442,452 of the receptacle faceplate 40 the extremities of the plug pins act on the cam surfaces 391,392 of the second shutter 39 forcing the second shutter to move downwards against the bias of the second shutter spring 395 thereby opening the shuttered circular apertures 442,452 and disengaging the extremities of the legs of the U-shaped second shutter 39 from the housing apertures 228, whereupon the receptacle moves against the bias of the receptacle compression spring 50 further into the housing 22 under the force of insertion of the two-pin plug, so that the wiping earth potential contact of the two-pin plug engages at least one of the top and bottom electrically conducting earth

potential strips 226,227, while the current-carrying pins engage and pass partially into the scroll portions 362,372 of the electrical terminals 36,37.

It will be understood that in this embodiment friction between a cylindrical two- pin plug and the housing 22 must be sufficient to hold the receptacle 30 in a recessed position with the two-pin plug inserted in the socket against the force exerted by the receptacle compression spring 50, in order for the swipe earth potential contact of the housing to remain in electrical contact with the swipe earth potential contact of the plug. However, friction between the receptacle and the housing must be sufficiently small that on extraction of the two-pin plug the receptacle 30, under a combined plug- retracting force and a force exerted by the receptacle compression spring 50 returns the receptacle 30 to the latching position with the faceplate of the receptacle substantially coplanar with the faceplate 21 of the socket. On returning the receptacle to the latching position, the second shutter spring 395 forces the extremities of the legs of the U- shaped second shutter 39 back into the housing apertures 228, to latch the receptacle 30 in the coplanar position.

A second embodiment 200 of the invention is shown in Figures 8 and 9, which is substantially the same as the first embodiment 10 except that additionally a mechanism, not shown, is provided for latching the receptacle in the recessed position with a second latching mechanism and releasing the receptacle from the recessed position by operation of a manually operable push button 71 operating on the second latching mechanism.

A third embodiment 300 of the invention is shown in Figures 10 and 11 which is substantially the same as the first embodiment 10 but without the facility for the second shutter to latch the receptacle in the coplanar position. Instead, the receptacle is lockable in the coplanar position by a rotatable ring 91 which engages the receptacle in a first rotational position and releases the receptacle in a second rotational position rotated with respect to the first rotational position. The ring is provided with opposed peripheral indentations 92 to accommodate a finger and thumb of a user to facilitate rotation of the ring. As in the first embodiment, no mechanism is provided for latching the receptacle in the recessed position.

Referring to Figures 12 to 16, a fourth embodiment of the invention 600 has a body 620 and an electrical terminal receptacle 630 moveable within the body 620 along a common longitudinal axis 11 thereof. As seen in Figure 13, the body 620

comprises a cuboid housing having a faceplate 621 and a right circular cylindrical open-ended housing 622 central of, and opening into, the faceplate 621, the cylindrical housing having a longitudinal axis substantially perpendicular to major faces of the faceplate and being located on a rear side of the faceplate 621. As orientated in Figures 12 to 16, an inner surface of the cylindrical housing 622 is provided with opposed substantially vertical first and second planar faces 61,62, the substantially vertical planar faces 61,62 extending from a rear of the housing to a location proximate a front of the housing. The vertical first and second planar faces 61,62 of the housing are separated by substantially horizontal first and second elongate slots 63,64 respectively, extending, parallel to the housing longitudinal axis, from a front end of the planar faces to a position proximate a rear end of the planar faces such that the slots are open at least at the front of the cylindrical housing 622. As orientated in the Figures, the cylindrical housing 622 has opposed top and bottom slots 623 piercing a wall of the cylindrical housing wall and extending parallel to the common longitudinal axis 11 substantially from the rear of the housing to the front of the housing. The faceplate 621 has two circular apertures 624 located one on each side of the central cylindrical housing on an imaginary horizontal line, as orientated in Figure 12, through a centre of the faceplate 621, for receiving bolts for fixing the socket to a socket box and thereby fixing a connector block insert 670, to be described herein, at least partially within the housing 620.

As orientated in the Figures, the terminal receptacle 630 includes a cylindrical, open-ended receptacle body 631, best seen in Figure 15, having on an outer cylindrical face opposed substantially vertical receptacle faces 321,322 divided substantially horizontally by elongate radially outwardly extending rectangular projections 323, 324, respectively parallel to a longitudinal axis of the cylindrical receptacle body 631, for sliding engagement of the vertical receptacle faces 321,322 with the vertical housing faces 61,62 respectively, and sliding engagement of the elongate rectangular projections 323,324 of the receptacle with the elongate slots 63,64 respectively of the cylindrical housing 622. The outer cylindrical surface of the receptacle body 631 also has a bottom elongate slot 327 parallel to the longitudinal axis of the cylindrical receptacle body 631 for sliding engagement with a lower leg of a U-shaped electrically conducting earth strip 676 to be described. Therefore the receptacle body 631 may slide longitudinally in the housing 622 but is prevented from rotating with respect to the housing about the coaxial longitudinal axes of the housing and receptacle body.

Referring again to Figure 15, proximate a top of the receptacle 630, the receptacle body 631 has a top elongate slot 633 extending from a front to a rear of the receptacle body parallel to a longitudinal axis thereof, for receiving a rectangular cross-section earth potential connector of an electrical plug. With the receptacle assembled in the housing, an upper leg of the earth strip 676 extends into the first elongate slot 633, to make electrical contact with an inserted earth potential pin of an electrical plug.

An inner volume of the receptacle body 631, between the top elongate slot 633 and the bottom elongate slot 327, is divided by spaced apart upper and lower horizontal dividers 610,611 extending from substantially a front of the receptacle body 631 to a rear of the receptacle body 631. Joining the upper horizontal divider 610 to the lower horizontal divider 611 are two spaced apart vertical walls 613,614, also extending from substantially the front of the receptacle body to the rear of the receptacle body. Volumes defined between the vertical walls 613,614 and the outer walls are further substantially centrally divided by further horizontal dividers 615, 616. The dividers and vertical walls thereby form, proximate each of the vertical receptacle faces 321,322, elongate substantially cuboid upper neutral and live housings 641,642 and lower neutral and live housings 651,652 extending from the front to the rear of the receptacle body parallel to a longitudinal axis thereof for receiving respectively first and second pairs of electrical terminals 647,646, 671,661 described herein. Coplanar with the further horizontal dividers 615,616 a bridging member 617 joins the spaced apart vertical walls 613,614 proximate a front of the receptacle body 631. Vertical walls 613,614 of the terminal housings 641,642, 651, 652 and inner faces of the receptacle body vertical faces are inset at a front face of the receptacle body to form cutaways similar to those shown for the first embodiment in Figure 2, to receive a first slidable shutter 38 in a manner described for the first embodiment.

As best shown in Figure 13, a lower live electrical terminal 636 has a U-shaped portion 661, and an L-shaped portion 662 rising from an outermost edge, in use, of an upper leg of the U-shaped portion 661. Thus, as shown in Figure 12, the L-shaped portion 662 is located generally above the U-shaped portion 661 with a first portion of the L-shaped portion parallel the longitudinal axis and a second portion of the L- shaped portion substantially perpendicular to the longitudinal axis and outward of the U-shaped portion and with the parallel legs of the U-shaped portion one above the

other parallel to the common longitudinal axis 11 of the receptacle 631 and housing 630, such that the lower live and neutral terminals 636,637 are open at a'front end thereof to receive extremities of plug pins inserted in the socket. The lower neutral electrical terminal 637 is a mirror image of the lower live electrical terminal 636. The lower live and neutral electrical terminals 636,637 are of resilient electrically conducting material and sized to form a friction fit in the lower neutral and live housings 651,652 respectively. In assembly the lower live and neutral electrical terminals are inserted through the rear of the terminal receptacle into the respective lower live and neutral housings 652,651. The lower legs of the U-shaped portions 661,671 are provided with downward perpendicular terminations for latching onto ridges, not shown, across bases of the lower live and neutral housings 652,651 for latching the U-shaped portions 661,671 in the live and neutral housings 652,651 to retain the terminals in the housings against an insertion force of pins of a plug being inserted therein. Outer slots, not shown, are provided in the further dividers 615,616 to accommodate the vertical portion of the L-shaped portion 662 of the lower neutral and live terminals such that a majority of the vertical portion of the L-shaped portion 662 is located in the corresponding upper live and neutral housing 642,641 respectively. However, other means of fixing the terminals in the housings 651,652 may be used, for example by welding, moulding or an adhesive.

As in the first embodiment shown in Figures 1 to 7, the first shutter 38 is an elongate strip of electrically insulating material disposed, as shown in the Figures, with a longitudinal axis substantially horizontal and major faces substantially vertical and perpendicular to the common longitudinal axis 11. The shutter is provided on a front major face proximate opposed ends thereof with cam surfaces 381,382 such that the shutter may be driven upwards by inserted pins of a plug (not shown). An upper face of the shutter is provided with a centrally located recess having a central vertical locating pin 383 for receiving a first end of a first shutter compression spring 385. In use the first shutter compression spring 385 passes through a cut-out 618 in a front edge of the upper horizontal divider 610 with a second end of the first shutter compression spring 385 bearing on an under outer face of a base of the upper elongate slot 633 such that the shutter is slideable upwards in the cutaways of the inner walls of the upper and lower terminal housings and the inner vertical faces of the receptacle body against a bias of the first shutter spring bearing on the under face of the first

elongate 33 and the central vertical locating pin 383 in the central recess of the first shutter.

As in the first embodiment shown in Figure 1, the receptacle is further provided with a receptacle faceplate 40 having a same transverse cross-section as the receptacle body, except that projections 423,424 corresponding with projections 323,324 on the receptacle body have further dog-leg projections 4231,4241 for engaging a rear surface of the faceplate 21 to limit forward movement of the receptacle 30. Also, as in the first embodiment, an inner surface of the receptacle faceplate is shaped to receive a slideable U-shaped second shutter 39, orientated in a parallel plane to the first shutter 38. An upper face of a base portion of the U-shaped second shutter 39 has a chamfered central projection and an opposed lower face of the base portion has a recess 393 for receiving a first end of a second shutter compression spring 395. The second shutter is provided on a front major face proximate opposed ends thereof with cam surfaces 391, 392 such that the shutter may be driven downwards by inserted pins of a plug. Upper ends of the legs of the U-shaped shutter are inwardly tapered to conform substantially with the outer cylindrical surface of the receptacle cylindrical housing 622 when the shutter is in a lowered position and to project above the outer surface when the shutter is in a raised position. In use the second shutter is biased upwards by the second shutter spring acting on the recess 393 and on the receptacle faceplate 40.

The receptacle faceplate 40 is provided with a top rectilinear recess 43 for alignment with the upper elongate slot 633. Live and neutral rectangular apertures 441, 451 are provided for alignment with the U-shaped portions 661,671 of the electrical terminals 636,637 located in the lower live and neutral housings 652,651 respectively. The faceplate is also provided with first and second circular apertures 442,452 for alignment with the upper live and neutral housings 642,641 respectively.

The receptacle faceplate is provided with a bottom recess 427 for alignment with the bottom elongate slot 327.

A rear face of the faceplate is further provided with two quadrant-shaped locating projections 46 for locating in generally quadrant-shaped volumes in the terminal receptacle 631 on both sides of the first elongate slot 633 respectively.

Referring to Figures 3 to 5, the housing 622 is similarly provided with two opposed apertures 228 (only one of which is shown for clarity) proximate an inner

surface of the faceplate 621 for receiving upper extremities of the legs of the U-shaped second shutter 39, when the second shutter is in an uppermost position.

The socket 600 is further provided with a connector block 670 for location in the housing 620, as best shown in Figures 14 and 16. The connector block 670 comprises a substantially cuboid connector block housing 671 for fitting at least partially within the socket housing 620 having a substantially central cylindrical housing 672 projecting from a rear face thereof for receiving the open-ended socket cylindrical housing 62. There is further provided a longitudinal channel 6721 on a side of the connection block containing a live terminal housing 673, offset from a base of the cylindrical housing 672, providing communication between the rear plate of the cylindrical housing 672 and the cuboid connection block housing 671. An upper wall of the connector block is provided with spaced apart live and neutral connector housings 673,674 parallel to the longitudinal axis having substantially semicircular transverse cross-sections and having connecting channels to the substantially central cylindrical connector block housing 672 projecting from a rear face of the connector block 671. Between the live and neutral connector housings 673,674, and parallel thereto, is a earth third connector housing 675 of inverted rounded U-shaped cross- section such that the earth connector housing projects further above the upper face of the connector block 671 than the first and second connector housings 673,674. As shown in Figure 16, each of the connector housings 673,674, 675 is in communication with the interior of the connector block housing, the earth connector housing 675 being open at its base, the neutral connector housing 674 being open across substantially all of its base and the live connector housing 673 being provided with a longitudinal slot 6731 in a base thereof. Each of the connector housings 673,674, 675 is further provided with a cut-out upper portion 6732,6742, 6752 at a rear end of the respective housing to permit access to a connector screw in connectors 93,94, 95 in each of the connector housings 673,674, 675 in an assembled socket. The earth connector housing 675 is also provided with a cut-out upper portion 6751 in a front end of the housing 675 so that in an assembled socket the earth connector housing 675 is in communication with a volume of the socket body 620 above the connector block housing 671.

As shown in Figure 16, a rear internal face of the cylindrical housing 672 of the connector block is provided with a central locating pin 51 for receiving a first end of a compression spring 50. On each side of the central locating pin 51 are diametrically

opposed live and neutral arcuate locating projections 641,642 convex towards the pin 51 for locating a live and a neutral terminal 646,647 for electrical connection to round pins of a plug respectively. Radially outwards of the arcuate locating projections are live and neutral connector locating pins 643 respectively. Proximate a top and a bottom of the rear plate of the connector block cylindrical housing are top and bottom rectangular apertures 644 for receiving legs 6761,6762 of a U-shaped earthing strip 676, to be described herein, the legs 6761,6762 being substantially parallel to the common longitudinal axis 11.

As shown in Figure 16, aligned with the apertures 624 on the socket housing faceplate there are provided on the rear face of the cuboid housing 672 of the connector block 670 opposed cylindrical projections 645,646 having central bores 6451,6461 respectively for receiving bolts, not shown, passed through the face plate apertures 624 to secure the socket to a socket box, not shown, and thereby secure the connector block 670 at least partially within the socket body 620.

Generally below the live connector housing 673, the rear face of the connector block cuboid housing 671 has first and second pairs of projections 681,682 of rectangular transverse cross-section aligned one above another for receiving between each pair of projections a respective fuse connector 71,72. Between each of the pair of projections there is provided on the rear plate a locating pin 683,684 for locating the respective fuse connector 71,72. A side of the cuboid housing of the connector block is provided with an inward dog-leg 69 to provide support for a fuse holder plate 73 on which the fuse connectors 71,72 are mounted.

As shown in Figure 14, the fuse holder plate 73 is rectangular and is provided with first and second fuse clip connectors 71,72 each comprising a generally U- shaped resilient metal strip at least one leg of which is inwardly concave for receiving a cylindrical terminal of a cylindrical cartridge fuse 74.

There is further provided a cylindrical earth connector 95 joined to an inverted U-shaped bolt earthing strip 951 by an L-shaped connecting metal strip 952 joined perpendicularly to a base of the inverted U-shaped earthing strip 951 with the earth connector 95 perpendicular to legs of the U-shaped earthing strip 951. The cylindrical earth connector is provided with a threaded aperture 953 in a cylindrical wall thereof for receiving a bolt of securing an earthing wire therein. The extremities of the legs of inverted U-shaped bolt earthing strip are provided with annular terminations 954 in a

plane of the inverted U-shaped bolt earthing strip, having central circular apertures for each receiving a respective bolt therethrough and making electrical contact therewith.

There is provided a live connector 93 similar to the earth connector 95, connected by a longitudinal portion of an electrically conducting live connecting strip 931 to a portion 932 inclined to the vertical terminating in a horizontal portion 933 for electrically contacting the upper fuse connector 71.

There is provided a neutral connector 94 similar to the earth and live connectors 95,93 connected to a vertical portion 941 of a live connecting strip which is connected at an end opposed to the neutral connector 94 to a base of a substantially U-shaped portion 942 the legs of which are parallel, as illustrated, to the common longitudinal axis, an inner of the legs being a right circular hollow cylinder 647 formed from a scroll with a single turn for forming a terminal for a circular cross-section neutral pin of a plug. The extremity of the outer leg of the U-shaped portion is provided with a transverse inward portion for contacting on the inner face thereof the transverse portion of the L-shaped portion of the U-shaped neutral terminal 637 for connection to a rectangular cross-section plug pin.

There is provided a hollow right circular cylindrical live terminal 646, also formed from a scroll with a single turn, forming an inner leg of a live terminal U- shaped portion 962 of a connecting strip, the outer leg being a mirror image of the outer leg of the U-shaped portion 942 of the neutral terminal connecting strip, for connecting to the L-shaped portion of the live U-shaped terminal 636 for connection to a rectangular cross-section plug pin. The base of the live terminal U-shaped portion 962 of the connecting strip is connected to an upper end of a vertical portion 963 which is connected at an opposed lower end to an L-shaped portion 964 for connection to the lower fuse connector 72.

The U-shaped earthing strip 676 has inwardly convex terminal portions 677 of the legs thereof. An upper end, as illustrated, of the base of the U-shaped earthing strip is provided with an L-shaped plate 678 having a first portion parallel and joined to the base and a second portion substantially parallel to the upper leg, for electrical connection to the earth connector 95.

Referring to Figures 14 and 16, the connector block 670 is assembled with the fuse holder 70 mounted on an inner face of the dog-legged portion 69 of the wall of the connector block housing 671 with the upper and lower fuse connectors 71,72

located on the corresponding locating pins 683,684. The live connector 93 is located in the live connector housing 673 the inclined portion 932 of the live connecting strip passing thorough the slot 6731 in the base of the live connector housing 673 to make electrical contact by the transverse portion 933 with the upper fuse connector 71. The neutral connector 94 is located in the neutral connector housing 674 with the vertical portion 941 of the neutral connecting strip passing through the base of the neutral connector housing 674 such that the cylindrical neutral terminal 647 is located against the concave surface of the neutral arcuate projection 642 and the neutral connecting strip is located on the neutral locating pin, not shown. The outer leg of the U-shaped portion 942 of the neutral connecting strip passes between an inner wall of the connecting block cylindrical housing 922 and an outer wall of the cylindrical housing 622 such that the transverse portions at the extremities of the outer legs of the U- shaped portions 942 protrudes through the slot 64. The live terminal connecting strip is located such that the cylindrical live terminal 646 is located against the concave surface of the live arcuate projection 641 and the live connecting strip is located on the live locating pin 643, a longitudinal portion of the L-shaped portion 964 passes through the channel 6721 and a transverse portion of the L-shaped portion 964 is in electrical contact with the lower fuse terminal 72. The outer leg of the U-shaped portion 962 of the live connecting strip passes between an inner wall of the connecting block cylindrical housing 922 and an outer wall of the cylindrical housing 622 such that the transverse portions at the extremities of the outer legs of the U-shaped portions 962 protrudes through the slot 63. The earth connector 95 is located in the earth connector housing 675 such that a vertical portion of the L-shaped portion 952 of the earth connecting strip passes through the notch 6751 in the front face of the earth connector housing 675 and legs of the earth connector strip 951 pass through respective opposed notches 692,693 in the inner edge of the upper face of the connector block cuboid housing 671 with the apertures in the terminal annular portions 954 of the strip aligned with the bores 6451,6461 in the cylindrical projections 645, 646 in the rear plate of the cuboid housing, for riveting the earth connector strip 951 thereto with hollow rivets, not shown. It will be understood that in the assembled socket, bolts may therefore pass through the apertures 624 in the faceplate 621 and through the hollow rivets to fix the socket to a socket box which is, for example, affixed to or in a wall. Legs of the U-shaped earthing strip 676 are passed through the upper and lower opposed rectangular apertures 644 in the rear plate such that the legs

protrude into the cylindrical housing 672 of the connector block 670 and the longitudinal portion of the L-shaped plate 678 makes electrical contact with the earth connector 95.

Referring to Figure 12, a receptacle compression spring 50 is located axially within the housing 622 bearing on the rear face of the cylindrical housing 672 of the connector block 671 and an inner face of the receptacle body 631 to urge the receptacle 630 to a location in which the dogleg projections 4231,4241 on the receptacle faceplate 40 engage a rear surface of the faceplate 621 and in which a front face of the receptacle faceplate 40 is substantially planar with a front face of the faceplate 621.

In use without a plug inserted in the socket, the receptacle 630 is urged forward by the receptacle biasing spring 50 so that a front face of the receptacle faceplate 40 is substantially coplanar with a front face of the faceplate 621. The second shutter 39 is urged upwards by the second shutter spring 395 so that extremities of the legs thereof enter the housing apertures 228 to latch the receptacle in position with respect to the housing 622 and faceplate 621. The cam surfaces 391,392 thereby close the circular apertures 442,452 respectively. Similarly, the first shutter 38 is urged downwards by the first shutter spring so that the first shutter cam surfaces 381,382 close the rectangular apertures 441, 451. In this position, the transverse portions of the L-shaped portions of the lower terminals 636,637 bear on inner faces of transverse portions at extremities of outer legs of the U-shaped portions 962,942 of the live and neutral connecting strips respectively, to make electrical contact therewith.

As in the first embodiment, when rectangular cross-section pins of a British Standard three-pin plug having an earth and live and neutral current carrying pins are inserted in the apertures 43,441, 451 the earth pin engages the top leg of the electrically conducting earth potential strip 676 and extremities of the current-carrying plug pins bear on the first shutter cam surfaces 381,382 to slide the first shutter upwards, opening the shuttered rectangular apertures 441,451 allowing the current- carrying plug pins to contact the U-shaped portions 661,671 of the terminals 636,637 by passing between the respective legs thereof.

As in the first embodiment, when, alternatively, circular cross-section pins of a two-pin plug having a peripheral earth potential strip contact are inserted in the circular apertures 442,452 of the receptacle faceplate 40 the extremities of the plug

pins act on the cam surfaces 391,392 of the second shutter 39 forcing the second shutter to move downwards against the bias of the second shutter spring 395 thereby opening the shuttered circular apertures 442,452 and disengaging the extremities of the legs of the U-shaped second shutter 39 from the housing apertures 228, whereupon the receptacle moves against the bias of the receptacle compression spring 50 further into the housing 622 under the force of insertion of the two-pin plug, so that the wiping earth potential contact of the two-pin plug engages at least one of the top and bottom legs of the U-shaped electrically conducting earth potential strip 676, as the terminal receptacle moves towards the rear plate of the cylindrical housing 62, the cylindrical upper live and neutral terminals 646,647 enter the rear of the upper live and neutral housings 642,641 respectively. As the terminal receptacle moves toward the rear plate the transverse portions of the L-shaped portions of the lower connectors 636,637 move along the slots 63,64 respectively. Extremities of round pins then enter the scrolled cylindrical terminals causing the scrolls to enlarge and bear on the walls of the upper live and neutral housings respectively to hold the receptacle substantially against the rear plate of the cylindrical housing 62.

It will be understood that in the fourth embodiments friction between the scroll portion of the terminals in the upper live and neutral housings with round plug pins inserted therein must be sufficient to hold the receptacle 630 in a recessed position with the two-pin plug inserted in the socket against the force exerted by the receptacle compression spring 50, in order for the swipe earth potential contact of the housing to remain in electrical contact with the swipe earth potential contact of the plug.

However, friction between the scroll portion of the terminals and the upper live and neutral housings with the plug pins removed and between the receptacle and the housing must be sufficiently small that on extraction of the two-pin plug the receptacle 630, under a combined plug-retracting force and a force exerted by the receptacle compression spring 50 returns the receptacle 630 to the latching position with the faceplate of the receptacle substantially coplanar with the faceplate 621 of the socket.

On returning the receptacle to the latching position, the second shutter spring 395 forces the extremities of the legs of the U-shaped second shutter 39 back into the housing apertures 228, to latch the receptacle 630 in the coplanar position.

Although sockets have been described for clarity in a particular orientation illustrated in the drawings, it will be understood that the sockets may be used in any

convenient orientation, for example with the faceplate angled to the vertical, or with the face plate horizontal.

Moreover, although sockets have been described in which the electrical terminal receptacle is moveable in a housing, it will be understood that the receptacle may be guided between the first position and the second position by other means, for example by guide rails.