GB2274210A - Electrical fitting or plug with casing joint, i.d.c. contact and cable clamp/stripper - Google Patents

Abstract

A housing of an electrical fitting, such as a plug, comprises halves with a male member (14A) extending from one half towards the other half of the assembled housing and a female member (16) formed in the other half. The male member (14A) has a deformable portion (112A, 112B) and the female member (16) has a complementally interengageable portion (114). A passage extends axially through the male member, and a locking pin (not shown) is axially slidable within the passage between a locked position, in which it allows disengagement of the two portions. The housing may include an integral cable retaining and stripping device (fig. 10A) embodied as a single piece having a blade (142) and flaps (136, 138) for retaining a cable. An insulation piercing contact (80, 82) both pierces a cable core at each terminal of the plug and clamps the core. The housing may be assembled and conductors connected thereto without the use of tools. <IMAGE>

Description

BACKGROUND TO THE INVENTION THIS invention relates to an electrical plug, and in particular to an electrical plug which does not require the use of external tools for wiring the plug.

Plug housings for conventional rewirable electrical plugs have a base and a lid which are connected to one another by means of at least one screw. A drawback of this arrangement is that a screwdriver is necessary to open the plug housing for enabling the plug to be rewired.

The electrical plug described in South African Patent No. 76/4206 is provided with a base and a lid having first and second respective projecting members which are releasably interengageable to secure the lid to the base. The base has a slot formed in it so that a suitable flat-bladed tool, such as a screwdriver, may be inserted into the slot and operated to disengage the interengaged formations. Although this plug avoids a need for screws, it still requires the use of a tool to disengage the base from the lid.

The connection of the individual insulated electrical wires to the pin terminals of an electrical plug can be a laborious and time-consuming process. The insulation has to be stripped from the ends of each of the individual wires using a suitable tool such as an insulation stripper or a knife. The multistrand conductor cores then have to be twisted and inserted into suitable apertures at the head of each pin, where they are clamped into position by means of screws. During the stripping process, the conductive core is prone to damage, as several strands of the core may inadvertently be cut while the insulation is being stripped from the end of the insulated wire. Moreover, a stripping tool is required to strip the insulation from the core, and a screwdriver is also needed to tighten the end of the screw up against the core in order to trap it in the aperture at the end of each pin.

A separate knife or cable stripper is also required to remove the sheath from a multi-core cable in cases where an unprepared length of cable is being used.

It is clear from the above that two or three separate tools are required to rewire a conventional electrical plug.

In the case of fuse-protected plugs, the fuse is often mounted externally of the plug housing, so as to avoid the step of having to remove the plug lid from the plug base in order to change the fuse. While externally mounted fuses are easier to replace, they are prone to moisture and damage.

SUMMARY OF THE INVENTION According to the first aspect of the invention there is provided a housing for an electrical fitting comprising two mateable halves, a male member extending from one half towards the other half of the assembled housing, a female member being formed in the other half, the male member having a deformable portion and the female member having a complemental portion which is interengageable therewith, a passage extending axially through the male member, and a locking pin being axially slidable within the passage between a locked position, in which it causes locking together of the deformable portion and the complemental portion, and a retracted position, in which it allows disengagement of the deformable portion and the complemental portion.

Preferably, the deformable portion is located towards the free end of the male member and is transversely deformable relative to the passage.

In a preferred form of the invention, the male member is in the form of a spigot having a radially expandable head portion, and the female member is in the form of a complemental socket having an expanded recess which is complementally shaped to accommodate the head portion.

Conveniently, the deformable head and part of the spigot is divided by a channel into a pair of deformable tongues, the tongues being dimensioned to be deformed inwardly towards one another by the socket walls as the spigot is inserted into the socket, and to engage against the expanded recess on full insertion of the spigot.

Advantageously, the locking pin has a manually grippable head, and a recess is formed in an outer face of one half of the housing for seating the head flush with or recessed relative to the outer face when the locking pin is fully inserted.

In a preferred form of the invention, the passage and the fully inserted locking pin extend completely through the assembled housing, with the end of the locking pin standing proud of the outer face of the other half of the housing.

The housing may be in an electrical plug housing, in which case one half of the housing from which the male member extends is the plug base and the other half within which the female member is formed is the plug lid.

Preferably, a plurality of terminal pins extend from the base, and the locking pin is insertable through the axial passage via the outer face of the base, so that the pin cannot be pulled out while the terminal pins are plugged into a socket.

The relative length of the locking pin and the depth of the plug housing are preferably such that, in the event of the pin being pushed out while the plug is plugged into a socket, the terminal pins are disconnected from the electrical supply before the locking pin has been sufficiently retracted to allow removal of the plug lid from the plug base.

According to a further aspect of the invention there is provided a cable retaining and stripping device for an electrical plug comprising a cable retainer for retaining in position an insulated electrical cable which is connectable to the plug, a stripping blade for stripping an insulating sheath from the electrical cable located on the cable retainer, and mounting means being provided within a housing for the electrical plug for accommodating the cable retainer.

Preferably, the cable is a multi-core cable surrounded by the insulating sheath.

The mounting means is preferably located adjacent a cable opening in the plug housing.

The blade is preferably mounted within the supporting cable retainer so as to have an effective cutting depth which variably matches the thickness of the insulating sheath it is designed to cut.

The mounting means conveniently comprises a pair of opposed slots located adjacent an opening in the plug housing, the opening being adapted to accommodate the insulated electrical cable.

The plug housing may be formed from a base and a lid, and pairs of slots may be provided in both the base and the lid for holding the cable retainer and the blade in position.

Conveniently, the cable retainer is movable within the mounting means between an exposed position, in which the blade is able to sever the sheath from the insulated electrical cable, to a safe position in which the cutting edge of the blade is concealed and the cable retainer is positioned to hold the cable in position.

The cable retainer may be in the form of a support having a substantially Hshaped cut-out formed therein so as to define a pair of adjacent resiliently deformable flaps separated by a gap.

The flaps may have contact edges adjacent the gap with cable-engaging jaws to prevent retraction of the cable once it has been inserted.

According to a still further aspect of the invention there is provided an electrical connector for forming an electrical connection between a conductive terminal and an insulated electrical wire comprising a channel sized to accommodate an end portion of the insulated electrical wire, piercing means arranged to be positioned over the channel in electrical contact with the terminal, clamping means for urging the piercing means towards the channel, and causing the piercing means to pierce through the insulation of the wire so as to provide electrical contact between the terminal and the conductive core of the insulated electrical wire, and actuating means for tightening and loosening the clamping means, the actuating means being carried on a housing which houses the electrical connector.

Preferably, the clamping means comprises a threaded shaft extending axially from a fixed end of the terminal, and a complementally threaded nut which screws onto the shaft.

The actuating means conveniently comprises a socket which is complemental with the nut and which is formed integrally with the housing.

The piercing means advantageously comprises an annular washer having a plurality of axially extending spikes spaced around the washer.

The terminal may comprise an electrically conductive pin which forms part of an electrical plug.

In a preferred form of the invention, the channel is annular in form, and extends around the outer periphery of the terminal.

Preferably, the channel is defined by the conductive terminal and a recess in a base to which one end of the conductive terminal is mounted.

The conductive terminal advantageously comprises a pin having a platform towards the fixed end of the pin which locates within a lower complemental portion of the recess and a threaded shaft of lesser cross sectional area than the platform extending therefrom, the channel being defined by the upper surface of the platform, the shaft and an upper portion of the recess.

Alternatively, the channel may be formed integrally with and of the same material as the pin.

The invention extends to an electrical plug comprising a housing having a base, a lid, first and second pins extending from the base and connection means for connecting first and second corresponding leads to the respective first and second pins, the connection means comprising a channel sized to accommodate the ends of the lengths of insulated wire, piercing means being in electrical contact with each pin, and clamping means for urging the piercing means towards the channel and for causing the piercing means to pierce through the insulation of each wire.

The first and second pins are typically live and neutral pins, and the first and second leads are live and neutral leads.

In a three pin electrical plug, an earth pin and a corresponding earth lead is naturally provided.

Conveniently, a connection piece is provided for connecting the live lead to the live pin via a fuse, the connection piece carrying the connection means at one end thereof and a first fuse cradle at the opposite end thereof, and the live pin terminating in a second fuse cradle, the first and second fuse cradles being arranged to accommodate a fuse within the plug housing, and the connection means comprising a channel sized to accommodate the ends of the lengths of insulated wire, piercing means being in electrical contact with each terminal pin, and clamping means for urging the piercing means towards the channel and for causing the piercing means to pierce through the insulation of each wire.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a top plan view of the base of a first embodiment of a three-pin electrical plug of the invention; Figure 2 shows an underplan view of a plug lid arranged to fit over the base of Figure 1; Figure 3 shows a top plan view of a base of a second embodiment of a three-pin electrical plug; Figure 4 shows an underplan view of a lid which is arranged to fit over the base of Figure 3; Figure 5 shows an exploded cross-sectional view along the lines 5-5 of Figures 3 and 4 incorporating a neutral pin and an exploded detail of a pin connector; Figure SA shows a detail of the exploded pin connector of Figure 5; Figures 6A and 6B show respective side and top plan views of an Lr piece carrying a cradle and arranged to fit within the base of Figure 3;; Figure 7 shows a partly cross-sectional side view of a connection piece of Figure 1 carrying a fuse cradle; Figure 8 shows part of a cross-section on the lines 8-8 of Figures 1 and 2 showing the plug base of Figure 1 mounted fast to the plug lid of Figure 2; Figure 8A shows respective top plan and side views of a locking pin which is used to lock the plug base to the plug lid; Figure 9 shows a section on the lines 9-9 of Figures 1 and 2 when the base and lid are assembled; Figure 10A shows a rear view of the base of Figure 1 with a cable retainer and wire stripper mounted in an operative position within the plug base; and Figure 10B shows a cross-sectional top plan view of a three core cable clamped in position within the cable retainer.

DESCRIPTION OF EMBODIMENTS Referring to Figures 1 and 2, a three-pin domestic electrical plug housing comprises a base 10 and a lid 12. A central spigot 14 extends upwardly from the interior of the base 10, and a complemental socket 16 is formed in the roof 18 of the lid 12. An oblong passageway 20 extends axially through the centre of the spigot. The precise manner in which the spigot 14 and the socket 16 interengage will be described further on in the specification.

Rectangular neutral and earth pin apertures 24 and 26 are formed through the base of the plug, and are bounded by respective part-circular turrets 28 and 30 which have openings 32 formed therein. A similar rectangular aperture (not shown) is provided for a live pin 34, and is partly bounded by a crescentshaped insulating spacer 36 extending upwardly from the base 10. A live connector 38 is mounted within a similar part circular turret 39. Both the live connectors 38 and the live pin 34 terminate in fuse cradles comprising respective pairs of prongs 40 and 42 which are arranged to carry a fuse 44, which may be in a range of differing amperages.

A semi-circular depression 46 is formed in the rear of the plug base, and a similar semi-circular depression 48 is formed in the rear of the plug lid 12, the depressions combining to form a circular aperture through which a three-core cable 50 is able to pass. A transverse slot or channel 52 is formed in the base 10 of the plug adjacent the semi-circular depression 46, and a similar transverse slot 54 is formed in the lid of the plug 12, and is arranged to cooperate with the slot 52 when the lid 12 is mated to the base 10. Housed within the elongate slot 52 is a cable retaining and stripping device 56, which will be described in more detail further on in the specification.

Referring now to Figures 3 and 4, a second embodiment of a plug base 58 is shown, which is similar to the first embodiment, with the exception that both the spigot 14A and the complemental socket 16A in the lid 60 are off-centre.

The reason for this is that the plug base 58 has a L-shaped recess 62 formed therein for accommodating an L-shaped connection piece 64 illustrated in Figures 6A and 6B, carrying a fuse cradle 66 formed from a pair of prongs 68 at one end, and terminating at its opposite end in a threaded spigot 70 arranged to carry a clamping arrangement for clamping the live wire in position.

In Figure 5, a neutral pin 72 is shown mounted in position within the rectangular aperture 24. A threaded shaft 74 extends axially from a platform 76 at the fixed end of the pin 72. A recess 78 is formed adjacent the turret 28. A piercing element, in the form of an annular spiked washer 80 has four equi-spaced spikes 82 protruding from its lower surface, as can be seen more clearly in Figure SA. Each spike has an arcuate cutting edge 84. The annular washer is sized to fit over the threaded shaft 74. Clamping means are provided by a threaded hex-nut 86 which is able to screw down onto the threaded shaft 74. A neutral insulated lead 88 is fed around the threaded shaft via the opening 32 illustrated in Figure 3, as is shown in broken outline.

Once the neutral lead is in position on the platform, the spiked washer 80 is brought down over the threaded shaft. The hex-nut 86 is then screwed down onto the shaft 74, thereby urging the spikes downwards against and then through the insulation 90 of the neutral lead 88.

As can be seen in Figure 4, the lid 60 has a pair of hex sockets 92 moulded into the upper surface thereof. The hex sockets are sized to fit the hex-nut 86, and are used to tighten the nut down over the shaft 74. It is clear from the assembled view of Figure 5 how tightening of the nut will cause the spikes 82 to pierce the insulation 90 of the neutral lead and to make electrical contact with the core 94 of the lead. The effectiveness of the electrical contact is ensured both by the number of spikes 82 and by the length of the arcuate cutting edges 84 of each spike. The hex sockets 92 are positioned towards the outer front edges of the lid 60, thereby allowing the rear end of the lid 12, when gripped, to serve as a lever arm to achieve sufficient tightening of the nut 86.

The outer periphery of the washer 80 is dimensioned to locate snugly within a round cylindrical portion 96 of the recess 78, and the extent of downward travel of the washer is limited by the depth of the cylindrical portion 96, as well as the floor of the platform 76, thereby preventing over-tightening of the nut 86. The earth pin is connected to the earth lead 98 in exactly the same manner.

The threaded shaft 70 carried by the L-piece of Figures 6A and 6B is designed to be fitted with a similar spiked washer 80 and a hex-nut 86. The end of a live lead 100 is fed through the opening 32 and around a channel defined between a part-circular turret 102 and the threaded shaft 70.

Turning now to Figure 7, the connection piece 38 of Figure 1 is shown carrying a fuse cradle comprising the pair of prongs 40. The connection piece 38 is mounted detachably within a recess 104 in the plug base 10. In order to connect the live lead 100 to the connection piece, the connection piece is withdrawn from the socket, and the hex-nut 86 and spiked washer 80, which are identical to those illustrated in Figure 5, are removed from the threaded shaft 106 of the connection piece 38. In order to facilitate the connecting operation, a pair of indents 108 may be provided in the base of the recess 104, the indents being sized to accommodate the free ends of the prongs 40 so as to allow the connection piece 38 to be firmly mounted in the inverted position. The live lead 100 is fed around a channel 110 formed within a central platform portion 111 of the connection piece.The spiked washer 80 is then passed over the threaded shaft 106, and the nut 86 is then screwed down tightly over the threaded shaft so as to urge the spikes 82 of the washer through the insulation of the live lead 100 thereby to establish electrical contact with the conductive core. One of the hex-sockets 92 is used to tighten the nut 86. Once the nut has been suitably tightened, the connection piece 38 is inverted back to its original position indicated in Figure 7, in which it fits snugly within the recess 104 and the turret 39.

Once the neutral, earth and live leads 88, 98 and 100 have been connected in the manner described, the lid 12 of the plug is then mounted to the base 10.

As can be seen in Figures 5 and 8, the spigot 14 which extends upwardly from the interior of the base has an enlarged head 112 which is arranged to nest snugly within a complemental expanded recess 114 formed towards the upper end of the socket 16. The passageway 20 which extends axially through the spigot is designed to accommodate a locking pin 116, which is illustrated in side and top plan views in Figure 8k The locking pin 116 is square cylindrical in form and is rectangular in cross-section, in order to prevent rotation thereof within the passage. A diametrically extending slot 117, which represents a diametric extension of the passage 20, divides the enlarged head portion 112 into inwardly deformable tongues 112A and 112B.

In order to increase waterproofing of the electrical plug when in an assembled position, an annular seat 118 is formed on the lower face of the plug lid 12, and a corresponding annular seat 120 is formed within the interior of the base 10 for accommodating an O-ring 122.

The locking pin 116 has a frusto-conical head 124 from which a shaft 126 extends, the shaft 126 terminating in a broadened paddle portion 128. A stepped portion 130 between the paddle 128 and the remainder of the shaft 126 locates against a seat (not indicated) within the passage 20 in order to prevent complete withdrawal of the locking pin 116. As can be seen in Figure 8, the end of the paddle 128 stands proud of the upper surface of the plug lid 12 when fully inserted. In the fully inserted position, it is also clear from Figure 8 that the head 124 of the locking pin 116 nests snugly within a complemental recess 130 formed in the lower face of the plug base 10, with the outer surface of the head 124 lying flush with the lower face.

When the plug needs to be disassembled for the purposes of rewiring, for instance, the pin 116 is removed by merely depressing that portion of the paddle 128 which stands proud of the upper surface of the plug lid 12. Once the pin 116 has been partly dislodged, the exposed pinhead 124 can then be gripped by the fingers and the pin can be retracted to the position in which the tongues 112A and 112B are able to deform inwardly into the vacant slot 117, thereby allowing the plug lid 12 to be separated from the plug base 10.

It is clear that when the electrical plug is plugged into a wall socket or the like, the pin 116 is held captive, with the head 124 of the pin locating against the face plate of the socket.

The only way in which the plug lid may be removed from the plug base while the electrical plug is still plugged in is by pushing down on the exposed portion 128 of the pin 116 and simultaneously withdrawing the plug from the wall socket. The length of the pin 116 and the axial displacement of the interengaging portions of the head 112 and expanded portion 114 of the socket is such that the terminal pins are disconnected from the electrical supply before the locking pin has been sufficiently retracted to allow removal of the plug lid from the plug base. For instance, a conventional three-pin domestic plug is disconnected from the electrical mains once it has been withdrawn a short distance from the face plate of the wall socket. The pin 116 has to extend by more than that distance before the tongues 1 12A and 112B are able to deform sufficiently so as to facilitate removal of the plug lid from the plug base.

Turning now to Figures 9 and 10A, the cable retaining and stripping device 56 has a body 132 formed from a plastics material such as reinforced nylon.

An H-shaped cutout 134 is formed in the body 132, and defines opposed resilient flaps 136 and 138. The gap 140 between the flaps is sized to accommodate the three-core cable 50 in a firm grip, with the flaps 136 and 138 being deformed inwardly and the flap ends serving as jaws which bite into the sheath of the cable 50, so as to prevent retraction thereof in the direction of arrow 141, as is clear from Figure 10B.

A blade runs along the upper portion of the body 132 The blade may be moulded integrally with the body, or may preferably be a separate steel razortype blade 142 which is embedded within the body. Referring to Figure 9, it can clearly be seen how the cable retaining and stripping device is housed within the complemental channels 52 and 54 of the respective plug base 10 and plug lid 12, with the blade 142 being housed within a complemental recess 144 at the base of the channel 52. If the sheath 146 of the three-core cable 50 has to be stripped away so as to expose the live, neutral and earth leads to permit them to extend individually to their respective pins, the lid 12 of the plug is removed, and the cable clamping and stripping device 136 is moved from the inverted position indicated in Figure 9 to an upright position indicated in Figure 10A in which the blade 142 is exposed.An end portion of the sheath 146 is severed from the remainder of the sheath by pressing the cable 50 downwards onto the blade 142.

The depth "h" of the blade 142 from the blade edge to the shoulder 147 of the body from which the blade 142 protrudes is such that it ensures that only the insulating sheath 146 is severed and, not the insulation surrounding the three central cores 148. In a preferred more versatile embodiment, the body is trapezoidal in shape, with a slanted shoulder, as is indicated in broken outline at 147A This slanted shoulder provides the protruding blade with a variable cutting depth. A sheathed cable can thus be moved to a selected position along the blade, depending on the thickness of the sheath.

After a portion of the sheath 146 has been removed, the cable clamping and stripping device 56 is moved back to the inverted concealed position shown in Figure 9 and the cable 50 is inserted through the gap 140 in the manner indicated in Figure 10B. An advantage of this aspect of the invention is that a separate blade or insulation stripper is not required when connecting an insulated cable to a plug. Furthermore, by combining the blade and cable retainer into a single removable component, very little modification to an existing plug housing is required. The blade is normally mounted in an unexposed, safe position, and it does not present a safety hazard.

In addressing the shortcomings of conventional plugs, the invention provides not only a significantly enhanced measure of convenience in both wiring and re-wiring an electrical plug, but also a number of concomitant safety benefits.

The principal advantage of the electrical plug of the invention is that no external tools are required to rewire the plug. The deformable spigot socket and locking pin assembly allows the base and lid of the plug to be manually locked together and separated. The integral stripping blade provides for stripping of the cable sheath, and the electrical connector in combination with the integral hex socket allows the individual leads to be connected without having to strip them.

Claims (36)

1. A housing for an electrical fitting comprising two mateable halves, a male member extending from a first half towards a second half of the assembled housing, a female member being formed in the second half, the male member having a deformable portion and the female member having a complemental portion which is interengageable therewith, a passage extending axially through the male member, and a locking pin being axially slidable within the passage between a locked position, in which it causes locking together of the deformable portion and the complemental portion, and a retracted position, in which it allows disengagement of the deformable portion and the complemental portion.

2. A housing according to claim 1 wherein the deformable portion is located towards the free end of the male member and is transversely deformable relative to the passage.

3. A housing according to either claim 1 or claim 2 wherein the male member is in the form of a spigot having a radially expandable head portion, and the female member is in the form of a complemental socket having an expanded recess which is complementally shaped to accommodate the head portion.

4. A housing according to claim 3 wherein the deformable head and part of the spigot is divided by a channel into a pair of deformable tongues, the tongues being dimensioned to be deformed inwardly towards one another by the socket walls as the spigot is inserted into the socket, and to engage against the expanded recess on full insertion of the spigot.

5. A housing according to any one of the preceding claims wherein the locking pin has a manually grippable head, and a recess is formed in an outer face of one half of the housing for receiving the head flush with, or recessed relative to, the outer face of said one half when the locking pin is fully inserted.

6. A housing according to any one of the preceding claims wherein the passage and the fully inserted locking pin extend completely through the assembled housing, an end of the locking pin standing proud of the outer face of one half of the housing.

7. A housing according to any one of the preceding claims wherein the housing is an electrical plug housing.

8. A housing according to claim 7 wherein the first half of the housing is the plug base and the second half is the plug lid.

9. A housing according to claim 8 wherein a plurality of terminal pins extend from the plug base, and the locking pin is insertable through the axial passage via the outer face of the plug base, so that the pin cannot be pulled out while the terminal pins are plugged into a socket.

10. A housing according to claim 9 wherein the relative length of the locking pin and the depth of the plug housing are such that, in the event of the pin being pushed out while the plug is plugged into a socket, the terminal pins are disconnected from the electrical supply before the locking pin has been sufficiently retracted to allow removal of the plug lid from the plug base.

11. An electrical plug including a plug housing and mounting means attached thereto, and a cable retaining and stripping device wherein the cable retaining and stripping device comprises a cable retainer for retaining in position an insulated electrical cable which is connectable to the plug, and a stripping blade for stripping an insulating sheath from the electrical cable locatable in the cable retainer, the cable retaining and stripping device being located in the mounting means of the electrical plug.

12. A plug according to claim 11 wherein the cable retainer is adapted to retain in position a multi-core cable surrounded by the insulating sheath.

13. A plug according to either claim 11 or claim 12 wherein the mounting means is located adjacent a cable opening in the plug housing.

14. A plug according to any one of claims l l to 13 wherein the blade has a cutting depth which varies along its length so that, in use, the depth of the blade may be selected to match the thickness of the insulating sheath to be cut.

15. A plug according to any one of claims 11 to 14 wherein the mounting means comprises a pair of opposed slots located adjacent an opening in the plug housing, the opening being adapted to accommodate the insulated electrical cable.

16. A plug according to any one of claims 11 to 15 wherein the plug housing is formed from a base and a lid, and pairs of slots are provided in both the base and the lid for holding the cable retainer and the blade in position.

17. A plug according to any one of claims 11 to 16 wherein the cable retainer is movable within the mounting means between an exposed position, in which the blade is able to sever the sheath from the insulated electrical cable, to a safe position in which the cutting edge of the blade is concealed and the cable retainer is positioned to hold the cable in position.

18. A plug according to any one of claims 11 to 17 wherein the cable retainer is in the form of a support having a substantially H-shaped cut-out formed therein so as to define a pair of adjacent resiliently deformable flaps separated by a gap.

19. A plug according to claim 18 wherein the flaps have contact edges adjacent the gap, and further have cable-engaging jaws to prevent retraction of the cable once it has been inserted.

20. An electrical connector for forming an electrical connection between a conductive terminal and an insulated electrical wire comprising a channel sized to accommodate an end portion of the insulated electrical wire, piercing means arranged to be positioned over the channel in electrical contact with the terminal, clamping means for urging the piercing means towards the channel, and causing the piercing means to pierce through the insulation of the wire so as to provide electrical contact between the terminal and the conductive core of the insulated electrical wire, and actuating means for tightening and loosening the clamping means.

21. An electrical connector according to claim 20 wherein the clamping means comprises a threaded shaft extending axially from a fixed end of the terminal, and a complementally threaded nut which screws onto the shaft.

22. An electrical connector according to claim 21 wherein the connector is located within a housing and the actuating means is carried on the housing.

23. An electrical connector according to claim 22 wherein the actuating means comprises a socket which is complemental with the nut and which is formed integrally with the housing.

24. An electrical connector according to any one of claims 20 to 23 wherein the piercing means comprises an annular washer having a plurality of axially extending spikes spaced around the washer.

25. An electrical connector according to any one of claims 20 to 24 wherein the terminal comprises an electrically conductive pin which forms part of an electrical plug.

26. An electrical connector according to any one of claims 20 to 25 wherein the channel is annular in form, and extends around the outer periphery of the terminal.

27. An electrical connector according to any one of claims 20 to 26 wherein the channel is defined by the conductive terminal and a recess in a base to which one end of the conductive terminal is mounted.

28. An electrical connector according to any one of the claims 20 to 27 wherein the conductive terminal comprises a pin having a platform towards the fixed end thereof, the pin being located within a lower complemental portion of the recess and a threaded shaft of lesser cross sectional area than the platform extending therefrom, the channel being defined by the upper surface of the platform, the shaft and an upper portion of the recess.

29. An electrical connector according to any one of claims 20 to 28 wherein the channel is formed integrally with and of the same material as the pin.

30. An electrical plug comprising a housing having a base, a lid, first and second pins extending from the base and connection means for connecting first and second corresponding leads to the respective first and second pins, the connection means comprising a channel sized to accommodate the ends of the lengths of insulated wire, piercing means being in electrical contact with each pin, and clamping means for urging the piercing means towards the channel and for causing the piercing means to pierce through the insulation of each wire.

31. An electrical plug according to claim 30 wherein the first and second pins are respectively live and neutral pins, and the first and second leads are respectively live and neutral leads.

32. An electrical plug according to either claim 30 or claim 31 wherein the plug further includes a third pin which is adapted to be an earth pin.

33. An electrical plug according any one of claims 30 to 32 wherein a connection piece is provided for connecting the live lead to the live pin via a fuse, the connection piece carrying the connection means at one end thereof and a first fuse cradle at the opposite end thereof, and the live pin terminating in a second fuse cradle, the first and second fuse cradles being arranged to accommodate a fuse within the plug housing, and the connection means comprising a channel sized to accommodate the ends of the lengths of insulated wire, piercing means being in electrical contact with each terminal pin, and clamping means for urging the piercing means towards the channel and for causing the piercing means to pierce through the insulation of each wire.

34. A housing for an electrical fitting substantially as herein described and illustrated.

35. An electrical connector for forming an electrical connection between a conductive terminal and an insulated electrical wire, substantially as herein described and illustrated.

36. An electrical plug substantially as herein described and illustrated.