Background Art Typically, rooms in buildings are fitted with a limited number of electrical power outlet sockets. An alternative is the installation of an electrical power distribution busbar system as illustrated and described in Australian Patent 721095. This system is designed to be mounted to the skirting board surrounding a room to receive adaptors anywhere along the length of the skirting board. Thereafter, a plug can be inserted into each of the adaptors. A major problem with this patent is that the aperture in the track is so large that children may insert a finger into it. The prongs of the plug also have proved to be vulnerable to damage.

Disclosure of Invention In a first aspect, the invention is an electrical plug for releasable connection to an electrical power and/or communications distribution busbar system, the plug comprising a housing and at least two prongs for electrical connection to respective conductors of the busbar; wherein: the housing has a body and a platform for insertion into the busbar system, the prongs being movable between a first retracted position within or against the platform, and a second deployed position in which they extend out of the platform, and the prongs are mounted to the platform such that they are spaced from each other along the platform.

At least two of the prongs also may be spaced from each other laterally across the platform.

The prongs may be rotated between the first and second positions. The angle of rotation between the first and second positions may be less than 90 degrees, conveniently between forty-five and seventy-five degrees, preferably substantially sixty degrees.

There may be three prongs; there may be more than three prongs, for instance for three phase.

The ends of the prongs may be angled or tapered. This aids insertion of the prongs into

the conductor.

Each of the prongs may be connected to a respective shaft that may extend through the platform into the body of the housing where it is connectable to a respective electrical circuit.

The platform may be thin, i. e. not substantially greater than 5mm, and preferably about 5 mm or less, preferably 3.5 mm or less.

The plug may comprise a cable connector for connecting a cable to the plug and a release mechanism for moving the prongs to their first position if the cable so connected is pulled.

The or each shaft may have an additional laterally extending formation that is engaged by a bolt, such that back and forth motion of the bolt translates into movement of the prong between the first and second positions.

The bolt may be biased to extend out of the housing when the prongs are in the first position, and the bolt is moved against the bias to engage a latching mechanism which retains it in the second position.

The latch mechanism may be releasable by manual operation of a switch or by the release mechanism to cause the bias on the bolt to move the prongs back to the first position.

The manually operable switch may be biased into the position in which it engages the bolt, and be manually operable to disengage it from the bolt.

The release mechanism may comprise a bell crank lever connected to a pivotable cable anchor.

The release mechanism may have a movable part that includes an appliance cable receiving port through which the appliance cable passes into the housing. The movable part may be biased to a resting position and be movable, by pulling on the appliance cable, to an extended position in which it automatically releases the latch mechanism.

The movable part may include a tongue between the bolt and the switch, the tongue being apertured so the switch can engage the bolt through the aperture, and the tongue moving with the movable part to drive the switch away from the bolt as it moves.

There may be a mechanism for preventing deployment of the prongs unless a cable has been attached to the plug. The preventing mechanism may operate to prevent movement of the bolt.

The electrical plug may comprise a socket for the insertion of a conventional plug and be adapted to connect the conventional plug to the electrical power and/or communications system.

In a related aspect the invention provides a busbar system comprising elongate housing structure having therein at least two elongate conductors laterally spaced from each

other and extending lengthwise of the housing structure, the housing having a slot extending parallel to the conductors to receive an electrical plug as set forth above, the width of the slot being not substantially greater than 5mm.

In a second aspect, the invention is an elongate electrical conductor which comprises two longitudinally extending panels disposed side by side and interconnected by a series (preferably loop-shaped) strap sections between a respective longitudinal edge of each panel, the panels either converging or extending parallel to each other from the interconnected edges throughout their extent.

The panels may be biased towards each other by the loops. The loops permit the bending of the conductors to allow the distribution system to be placed around corners, and shaped to fit a room without the need for the conductors to be cut and reconnected at the corners.

The construction is such that it enables the conductor to be wound on to a drum for storage before use.

A said panel may have a region of weakness near its unconnected edges to enable a portion of the panel adjacent that edge to be flared outward, when the conductor is installed in a channel of an insulating housing. Preferably both edges of the panel have such a region of weakness.

Preferably the panels are approximately equal in extent, in particular the conductor may be symmetrical about a longitudinal plane passing through the mid-point of the loops.

This flare, which is present after installation, helps to receive the prongs of a conductor. The flare also increases the rigidity of the conductor.

In use, the platform is inserted adjacent the conductors with the prongs retracted, subsequent extension of the prongs causes them to be inserted into the conductors. Each conductor receives a respective prong inserted first between the flared ends and then between the panels, forcing the panels apart so that electrical contact is established along opposed side surfaces of the prong and along the corresponding opposed inside surfaces of each panel.

The platform may be inserted below the conductors.

Insertion of the prong forces the panels apart so that electrical contact is established along two parallel lines of contact.

An electrical power and/or communications distribution busbar system may include a plurality of conductors according to the second aspect of the invention, and may also include a first insulating housing to receive two or more of the conductors in separate channels.

The busbar system may also include a second insulating housing which is able to be

fixed to a wall, and to receive the first insulating housing such that a small gap extending along the busbar is left between the two housings for the entry of the platform of a plug.

Advantageously, this gap is typically designed to be smaller than a child's finger. The gap is governed by the thickness of the platform, which is advantageously as thin as possible.

A said housing (preferably the second housing) may comprise a flexible lip or flange which covers at least one of the conductors in a first position and may be flexed to a second position to allow access to the conductor.

The flexible lip may cover the horizontally extending gap in the first position.

Preferably the flexible lip is integral with the housing and preferably is continuous along the length of the housing.

The width of the horizontally extending gap may be relatively small, i. e. less than the width of an adult's finger, most preferably being less than the width of a child's finger e. g.

5mm or less, as mentioned in the context of the first aspect of the invention.

The housing may have only two components.

The busbar system may further comprise a terminal block, suitable for connecting the system to a conventional system, comprising at least two flanged connectors arranged spaced apart side by side, for insertion into a respective said conductor each flanged connector being electrically connected to a conventional terminal.

In a third aspect the invention provides an elongate insulating housing for a busbar system, comprising parallel channels to receive at least two elongate conductors, adapted to be fixed to a wall and to provide a gap extending longitudinally of the housing for the entry of a platform of a plug, and comprising a flexible lip which covers at least one of the conductors in a first position and may be flexed to a second position to allow access to the at least one conductor.

The insulating housing may comprise a first elongate housing in which the parallel channels are disposed and a second elongate housing which is adapted to be fixed to a wall and to receive the first housing, the two housings providing the longitudinally extending gap.

The flexible lip preferably is provided on the second housing.

The flexible lip may be integral with the housing, and may cover the horizontally extending gap. The flexible lip is preferably continuous along the length of the housing.

There may be a recess in a said housing into which the lip is deflected when flexed.

The flexible lip may extend parallel to the parallel channels in its first position.

In a further aspect of the invention, there is provided an insertion tool for inserting a conductor into a housing for an electrical power and/or communications distribution busbar

system, the housing having a channel for receiving the conductor, the conductor comprising two longitudinally extending panels disposed side by side, the insertion tool comprising means for flaring at least one of the panels of the conductor. This can enable more efficient installation of the busbar system.

The flaring means may comprise a flaring member having a tapered edge. The flaring member may comprise a thin rib extending outwardly from the edge. This may enable the conductor to be flared more accurately.

The flaring member may be rotatable, and may be a disc having a tapered outer portion. This may make the tool easier to operate.

For more accurate and reliable operation, the insertion tool may comprise two adjacent rollers for clamping the conductor and guiding it past the flaring member. The rollers may have tapered portions corresponding to the tapered edge of the flaring member so as to define two separate paths between the flaring member and the tapered portions of respective rollers through which portions of respective panels of the conductor may pass, thereby flaring the panels.

The panels of the conductor may be joined at respective first edges, in which case the flaring means may be adapted to flare a panel along its opposing second edge to a predetermined depth. The predetermined depth may correspond to a region of weakness near the second edge of the panel. In this way, the conductor can be flared more accurately.

The insertion tool may be adapted to insert a plurality of conductors simultaneously into the housing, the tool comprising a plurality of such flaring means.

The insertion tool may further comprise: an insertion block having a passage for receiving the housing; and insertion means arranged adjacent to the passage for receiving the conductor and guiding it into the housing.

The insertion means may be movable with respect to the insertion block to enable access to the passage. In this way, the insertion process may be started manually.

The insertion tool may further comprise means for supporting a drum for supplying the conductor to the insertion tool, and may comprise a roller for feeding the conductor from the drum to the flaring means.

The insertion block may be pivotally mounted on a base, which can simplify operation of the tool, especially when the tool is used in confined spaces.

This feature is also provided independently. Accordingly, in a further aspect of the invention, there is provided an insertion tool for inserting a conductor into a housing for an electrical power and/or communications distribution busbar system, comprising an insertion

block having a passage for receiving the housing, and wherein the orientation of the insertion block is reversible.

The insertion block may be pivotable between opposite first and second orientations.

The insertion tool may further comprise complementary retaining formations on the base and insertion block for retaining the insertion block in either of the first and second orientations.

This can prevent the insertion block being moved accidentally while in use.

In a further aspect of the invention, there is provided a method of inserting a conductor into lengths of housing for an electrical power and/or communications distribution busbar system, using an insertion tool having an insertion block with a passage for receiving the lengths of housing, the method comprising: passing a first length of housing through the insertion block, thereby inserting the conductor into the first length of housing; inverting the orientation of the insertion block; and passing a second length of housing through the insertion block, thereby inserting the conductor into the second length of housing.

This can make the insertion process easier and more efficient, for example when carried out in confined spaces.

The method may further comprise passing the first length of housing alongside the insertion block as the second length of housing is passed through the insertion block. The insertion block may be pivotally mounted on a base, and reversing the orientation of the insertion block may comprise pivoting the insertion block between opposite first and second orientations. Lengths of housing may exit the insertion block at the head of the insertion block after insertion of the conductor, in which case the insertion block may be pivoted about the head. This can make the insertion process easier to carry out.

Brief Description of Drawings Non-limiting examples of the invention will now be described with reference to the accompanying drawings; in which: Fig. 1 is an expanded view of a plug; Fig. 2 is a perspective view of the plug in its compact form from the front; Fig. 3 is a perspective view of a cable-receiving block within the plug from the rear; Fig. 4 is a horizontal sectional view through the plug; Fig. 5 is a perspective view of a prong; Fig. 6 is a perspective view of the plug from the rear when not in use; Fig. 7 is a perspective view of the plug from the rear in the tripped position ; Fig. 8 is a cut away perspective view of the housing from the rear in a mid trip

position; Fig. 9 is a cut away perspective view of the housing from the side in a mid trip position; Fig. 10 is a perspective view of the front housing part of the plug from the rear; Fig. 11 is a perspective view of the front housing and cable receiving block; Fig. 12 is a further cut away perspective view of the plug in a mid trip position; Fig. 13 is a cut away perspective view of the plug in the tripped position; Fig. 14 is a front view of a busbar electrical conductor; Fig. 15 is an end view of a busbar electrical conductor; Fig. 15a is an end view of an alternative embodiment of a busbar electrical connector; Fig 15b is a view of an alternative embodiment of a busbar electrical connector; Fig 15c is a front view of a further embodiment of a busbar electrical connector; Fig. 16 is an expanded side view of the first and second insulated housings containing the conductors of Fig. 15a ; Fig. 16a is a side view of the first insulating housing within the second insulating housing of Fig. 16; Fig. 16b is an expanded view of alternative forms of the insulating housings; Fig. 17 is a side view of the electrical conductor of Fig. 15 with a prong inserted; Fig. 17a is a perspective view of the electrical conductor of Fig. 15 with its edges flared; Fig. 18 is a perspective view of the flexible nature of the electrical conductors; Fig. 19 is a perspective view of the plug and electrical power and communications busbar system in use; Fig. 20 is a cross sectional view of the plug and electrical power and communications busbar system of figure 19; Fig. 20a is a cross-section corresponding to Fig. 20 of the system using different versions of the conductors and the housings; Fig. 20b is a perspective view of a busbar system and two different types of plug, one being as in Fig. 20a; Fig. 21 is a perspective view of a terminal block for an electrical power and communications system; Fig. 22 is a side view of the terminal block; Fig. 23 is a side view of the terminal block when connected to the system; Fig. 24 is a perspective view of a second type of plug with prongs in a first position;

Fig. 25 is a perspective view of the plug of Fig. 24 with the prongs in a second position; Fig. 26 is a perspective view of the plug of Fig. 24 with its cover removed; Fig. 27 is a side view of the plug with its cover removed; Fig. 28 is a top view of the plug with its cover removed; Fig. 29 is an exploded view of the plug of Fig. 24, showing detail of the cable attachment; Fig. 30 is a perspective view of the cable attachment; Fig. 30a provides an end view of the housing; Fig. 30b shows a perspective view of the housing from below; the housing being partly cut away; Fig. 30c provides an upper perspective view of the housing having its cover and some elements removed; Fig. 30d is a perspective view of a bolt 40; Fig. 31 is a perspective view of a third type of plug with the prongs in the first position; Fig. 32 is a perspective view of the plug of Fig. 31 with the prongs in the second position; Fig. 33 is a front view of the prongs in the second position; Fig. 34 is a side view of the prongs in the second position; Fig. 35 is a perspective view of a prong; Fig. 36 shows a perspective view of a rear and a front insulating housing for a corner piece; Fig. 37 shows a perspective view of a flexible plastic cover; Fig. 38 shows a perspective view of the cover and the rear housing in situ; Fig. 39 is a perspective view of an insertion tool; Fig. 39a is a close-up view of part of the insertion tool; Fig. 40 is a perspective view of a flaring assembly; Fig. 41 is a close-up view of part of the flaring assembly; Fig. 42 is a perspective view of an insertion head; Fig. 43 is a side view of the insertion head; Fig. 44 is a view of the insertion tool with the insertion block pivoted away from the base; Fig. 45 is a perspective view of an alternative embodiment of the insertion tool; Fig. 46 is a view of the insertion tool folded up;

Fig. 47 is a perspective view of an alternative embodiment of the flaring assembly; Fig. 48 is a front view of a flaring unit; Fig. 49a is a perspective view of a mechanism for releasably mounting a drum; Fig. 49b is a view of the mechanism of Figure 49a when activated; Fig. 50 is a perspective view of a mounted drum; Fig. 51 is a perspective view of the insertion tool with the insertion head slid partially out of the insertion block; and Fig. 52 is a view of the alternative embodiment of the insertion tool with the insertion block pivoted away from the base.

Description of Embodiments Figures 1 and 2 show an expanded view and compact view respectively of an electrical plug 10 illustrating some of its components. The plug 10 includes a housing 12, an electrical connector block 14, a cable receiving block 16 and a housing front 18. The housing front 18 has a cable port opening 20 in which to receive a plug and cable, a swinging plate 22 and a tongue 24. The cable-receiving block 16 has a cable port 26 and a series of tortuous paths 28. The cable receiving block 16 attaches to the rear of the swinging plate 22 of the front housing 18 such that the cable port 26 extends through the cable port opening 20.

A cable having insulated electrical wires pass through the cable port opening 20 in the housing front 18 and the cable port 26 in the associated cable receiving block 16.

The individual wires of the cable are then threaded through respective tortuous paths 28 to be passed through respective openings 30 in the upper face of the electrical 20 connector block 14. Each of the wires terminates at the connector block 14 by being secured to the connector block 14 by respective screws 32. This forms the respective electrical circuits. The electrical connector block 14 is fitted into the interior of the housing 12 such that the electrical wires can make an electrical connection to a first end 52 of respective prongs 34 in the housing 12.

The housing 12 includes a thin platform 36 for insertion into a busbar system. Each of the prongs 34 is mounted to the thin platform 36. Each prong 34 is connected to a respective shaft that extends through the platform 36 and into the interior of the housing 12.

The housing 12 further includes a switch 38 which operates in conjunction with a spring loaded bolt 40 to readily enable a user to operate the plug to power the electrical circuits.

The plug 10 in its assembled form is shown in figure 2. The spring loaded bolt 40 is illustrated. On the front side of the bolt 40 is a retaining notch 41.

The path of the insulated electrical wires through the cable-receiving block 16 is in part schematically illustrated in figure 3. The cable passes through the cable port 26 where it is firmly gripped by a pair of cable grippers 42 and a clamp (not shown). The electrical wires are then separated and each of the wires is fed through one of the tortuous paths 28.

Figure 4 shows a horizontal sectional view through the housing 10 as shown by the dashed line A-A in figure 1. An insulator 44 insulates each of the screw ends 32 mounted in the electrical connector block 14. An electrical connector 46 is positioned over the end 52 of each of the prongs 34. Each electrical wire, and its associated screw 32 and electrical connector 46 are all at the same electrical potential.

Figure 5 details the configuration of a prong 34. The prong 34 is cylindrical in section and the first end 52 is necked to enable the electrical connector 46 shown in figure 4, to be securely fastened to it, whilst permitting the prong to rotate. The first end 52 of the prong 34 extends generally in the direction defined by axis 58. The second end 54 of the prong 34 is generally transverse to axis 58 and shaped to facilitate easy insertion into the conductor of a busbar. A serpentine formation 56 in the shaft 55 creates a lever to facilitate rotation of the prong 34 about axis 58.

Figure 6 shows a rear view of the housing 10 when not in use. The spring loaded bolt 40 is biased to extend out of the housing 10 in this position. A recess 60 is provided in the platform 36 for each of the respective prongs 34. The prongs 34 are mounted to the thin platform 36 and movable between this illustrated first position and a second position as illustrated in figure 7 in which the prongs 34 in use extend out of the platform. The depth of the platform 36 is approximately three and a half mm.

As shown in figure 7, the spring loaded bolt 40 has been pressed into the interior of the housing 10 so that the prongs 34 rotate out of their respective prong recesses 60 ready for use.

Effectively the bolt 40 is moved against the bias and the retaining notch 41 catches on a latch (not shown), carried by switch 38. This latch is operated by pressing switch 38 and it retains the bolt 40 in this second position. Tongue 24 is captured between the latch and the retaining notch 41 when the bolt 40 is latched into the second position.

Details of the rotation of the prongs from the second to the first position is illustrated in Figure 8 and figure 9 which show cut away rear and side views respectively of the housing 10 in a mid trip position. In this position, switch 38 has been switched to disengage latch from retaining notch 41. This causes the spring loaded bolt 40 to shoot out of the interior of the housing 10 under its bias. Since the prong 34 levers 56 are engaged by an apertured rack 57 of the bolt 40, the motion of the bolt 40 out of the housing 10 translates into movement of the

prongs 34 towards the first position and towards the prong recesses 60..

A hinge 80, and a spring 82 which is anchored to a notched wedge 84 are attached on opposite sides to the rear of the housing front 18 to facilitate swiveling of the plate 22. Figure 10 illustrates the rear view of the housing front 18 incorporating this arrangement whereby the swinging plate 22 is biased to a resting position. Figure 11 shows this arrangement, together with the cable receiving block 16 which work together to provide a safety mechanism. In use, if the cable which passes through the cable port is pulled, say for instance by someone tripping over the cord, the swinging plate 22 pivots about the hinge 80 which causes tongue 24 to draw away from its position between the latch and the retaining notch 41 and this causes the latch to release. This in turn causes the spring loaded bolt 40 to shoot out from the interior of the housing 10 and the second end 54 of each prong 34 to disengage from its engagement with the busbar disconnecting the supply of electricity.

Figure 12 details the latching mechanism which includes the switch 38, latch, tongue 24 and retaining notch 41. The tongue 24 extends between the notch 41 and switch 38. The tongue 24 is apertured so that the switch 38 can engage the retaining notch 41 through the aperture. The latch mechanism is releasable by manual operation of the switch 38 to cause the bias on the bolt 40 to move the prongs 34. Figure 13 provides further detail of the switching of switch 38 to cause engagement of the latch with the retaining notch 41.

The elongate electrical conductor 90 into which the second end 54 of prong 34 is inserted is shown in figures 14 and 15. The conductor 90 has a pair longitudinally extending panels 92 arranged spaced apart, side by side, and interconnected by a series of loop-shaped strap sections 94 along their upper edges. As shown in figure 15, the panels 92 are set relative to the loops 94 such that they converge and their lower edges are closer together than their upper edges. In an alternative form as shown in figure 15a the panels are set so as to be parallel to each other. In both cases the resilience of the material forming the loops biases the panels towards each other if they are displaced outwardly from the positions shown; the gap between the panels is less than the thickness of the ends 54 of prongs 34 so that movement of the prong forces the panels apart, the resultant biasing force form the loops ensuring the panels grip the prongs in good electrical contact therewith. Near the lower edges of the panels 92 is a line of weakness formed by a groove 96. This enables the ends of the panel to be flared when inserted into a housing as described below. By having unflared ends until insertion into the housing the conductor remains relatively flat and pliable. It thus can be reeled on a drum for convenient storage and transport. It also better accepts bending when fitted around corners as described with reference to figure 18 below.

An alternative conductor 91 is illustrated in figure 15b. This conductor also has a pair of longitudinally extending panels 93 interconnected by a series of loops 95, but has a line of perforations 97 extending along the lower edges of the panels which provides a line of weakness. Alternatively, as shown in figure 15c, both a groove and a row of perforations may be provided. In this figure the conductor is shown covered by a flexible extruded insulating plastics sheath 99. The other embodiments of the conductor may be similarly sheathed.

An electrical power and communications busbar system 100 is illustrated in figures 16 and 16a. The system 100 includes a first insulating housing 102, which has three channels 104; each shaped to receive an electrical conductor 90 described with respect to figures 14 and 15. A second insulating housing 106 is provided and shaped to receive the first insulating housing 102.

A small horizontal gap 108 is provided between housings 102 and 106 into which the thin platform of a plug as previously discussed may be inserted. The depth of the gap 108 is sufficiently small to prevent small children from being able to insert a finger into it. A further gap 110 is provided between the first insulating housing 102 and the second insulating housing to enable a screw to be inserted to screw the second insulating housing 106 to a wall or other permanent structure. As illustrated in figures 17 and 17a, the groove 96 enables the lower ends of the panels 92 to be flared outwards by a suitably-shaped tool such as a profiled wheel as described hereafter when the conductor of figure 15 is installed in a channel of the first insulating housing. This flaring 98 facilitates the passage of the prong 34 of a plug 10.

After insertion of a prong 34 the panels 92 are substantially flat along straight lengths of the first insulating housing 102.

The conductors 90 are flared before they are inserted into the first insulating housing 102, and the flaring holds the conductors 90 in the housing 102.

Figure 16b shows a different housing, suitable for the conductor shown in Figure 15a. In this conductor, after insertion of a prong, the panels 92 are substantially flat along straight lengths of the first insulation housing 102. In this embodiment, the second insulating housing 106 has an upstanding flexible lip or flange 107. The flange is continuous along the length of the housing, and is provided as a co-extrusion with the main body of the housing 106. The flange 107 prevents water or debris entering the live and neutral conductors when the housings 102,106 have been assembled, but is flexible so as to be deflected locally to permit the thin platform portion of the plug to pass into the housing. The lip 107 can be placed more forward if desired to protect also the earth conductor. A recessed depression 109 is provided immediately behind the flange 107 to accommodate it when deflected by the platform 36.

This reduces the risk that the lip 107 will break when flexed.

Referring to figure 20b, the second insulating housing 106 is able to be mounted around the sides of a room, whether that room is square, circular or of any other configuration. The housings 102,106 are cut to length so as to stop just short of an internal or external corner, and the conductors are bent around the corner as necessary to conform to it, as shown in figure 18. The conductors 90 are separated by a flexible plastic housing that is placed over the active and neutral conductors and then a cover (eg 103, figure 20b for an external corner) with internal partitions to separate and insulate the conductors from each other is fitted over the exposed conductors at the corner.

Figures 19 and 20 show the plug and electrical power and communications busbar system together 110 in use. As here illustrated, the conductors and insulating housings are as in figures 14,15 and 16. A power cord 112 extends from the cable port 26.

Initially, the thin platform 36 of the plug is inserted into the small horizontal gap 108 between the first and second insulating housings 102 and 106 respectively with the prongs retracted. Depression of the spring loaded bolt 40 into the interior of the housing and switching of the switch 38 such that the switch latch captures the retaining notch causes extension of the prongs into the conductors from below. Each conductor receives a prong inserted first between the flared ends and then between the panels, forcing the panels apart so that electrical contact is established along opposed side surfaces of the prongs and along the corresponding opposed inside surfaces of each panel. Figure 20a shows the plug 10 inserted into a busbar formed of the conductors of figure 15a and the housings of figure 16b. Here the ends 54 of the prongs 34 are tapered so as better to conform to the diverging slot presented by the hitherto-parallel faces of the figure 15a conductors when displaced. Further it can be seen that the flexible lip 107 has been locally deflected or folded into the depression 109.

Figs. 21 and 22 show a terminal block 114 which may be used to attach the busbar to a conventional power supply. The terminal block comprises three conductive flanges 116 (or only two if no earth connection is to be provided) which are arranged generally parallel to each other and spaced apart by channels 118. The flanges 116 are mounted on insulating projections 120,122, 124, which successively project further from a base 126 of the terminal block 114, with the result that the flanges are offset from each other.

Each flange 114 is formed in the shape of a rectangle, having a length along the terminal block which is much longer than its height. As shown in Fig. 22, an upper edge of each flange is tapered to provide an upper narrow ridge.

In order to connect the terminal block 114 to the busbar, as shown in Fig. 23, the flanges

116 are engaged with corresponding conductors 90 in the first insulating housing 102 and the block and the conductors are push-fitted together. The second insulating housing 106 can then be push fitted over the first insulating housing 102. A conventional power supply may be connected to conventional screw-type terminals 128, which inter-connect to respective flanges inside the terminal block. The conductor 90 nearest the entrance to the narrow slot 108 is made the earth or ground connection, as it is the most vulnerable to objects inserted in the slot by small children.

Figs. 24 to 30 show a further embodiment of an electrical plug 10 having prongs 34 in a retracted and extended state respectively. Parts already described bear the same reference numerals. As shown by Fig. 27, when in the extended position, the prongs 34 are at an acute angle, typically between 45 and 75°, preferably around sixty degrees, to the thin platform 36.

Figs. 26 to 30 show the safety catch mechanism of this embodiment in further detail. A cable enters via sleeve 136 and is secured in cable anchor 137 by a screw 137a. The three flexible wires (L, N, E) of the cable are taken to a connector block 139 whereat they are connected by resilient wiper connectors 46 to the ends 52 of the prongs 34, as already described with reference to figure 4. The wires are covered by a lid 142, so as to be fixedly secured relative to the connectors 46.

The cable anchor 137 is cylindrical in shape and is rotatably mounted in arcuate guides 141 and bearing 141 a. Fixed on top of the cable anchor is a bell crank lever 138. A cable port 140 has an aperture shaped so that untoward pulling of the cable permits the sleeve 136 to move slightly and thus rotate the cable anchor and the bell crank lever 138 through a few degrees. Short lengths 143 of the flexible wires which are unconstrained by the cover 142 permit this rotational movement.

A bolt 40 is biased by a spring 45 to move the prongs 34 into the retracted horizontal position as described with reference to figure 4. It is latched in the'on' (prongs raised) position by a switch (toggle catch) 38, which captures an arm 149 extending sideways from the bolt 40. One end of the bell crank lever 138 has a wedge-shaped formation 147 which is fitted beneath a correspondingly-shaped wedge 148 carried by the toggle catch 38. Tension on the cable, such as to rotate the bell crank and move the wedge 147 towards the toggle catch, will lift the wedge 148 and thereby also the toggle catch, releasing the arm 149 of bolt 40. The prongs 34 then are withdrawn and the plug is free to be pulled out of the busbar. A return spring 155, visible in Figures 28 and 30b, biases the bell crank lever clockwise seen from above.

As shown in Figures 30a-30c, in normal operation the arm 149 attached to the bolt 40

slides freely above a shorter arm 151 of the bell crank lever 138. However if no cable has been fitted to the plug and the bell crank lever 138 has been rotated clockwise by the spring 155, a small resilient lug 153 is uncovered, which can then rise up. This lug 153 prevents the arm 149 of the bolt 40 from sliding back and so the prongs remain in their retracted position and the plug cannot be inserted into the rail. This is a safety feature, as it prevents live parts from being accessed, e. g. by a child inserting a partially-dismantled plug into the rail.

Figure 30d shows a perspective view of the bolt 40 showing the arm 149 which, in use is captured beneath switch 38, and rack 57 which engages levers 166 (fig. 35) of the prongs 34.

A further example of a plug 150, which is an adapter for enabling conventional plugs (here a UK 3-pin plug) to be connected to the busbar, is shown in Figs. 31 and 32. Fig. 31 shows the socket 150 with its prongs 34 recessed in a thin platform 36 which extends from the side of the socket 150. The adapter further includes a two part housing having a platform part 154 and plug receiving part 156 having three holes 157 for the plug pins. The adaptor also includes a spring loaded bolt 158, which operates in conjunction with a restraining latch 160 on the platform part of the housing to engage the prongs with their respective conductors until released by manual release of the latch 160. The arrangement and operation of these parts is generally as already described, except that no safety release in response to excess cable tension is required; in such circumstances the plug pins will be pulled from the holes 157. In use, the bolt is moved against its spring bias and a retaining notch in the bolt is engaged by the latch 160. The latching occurs automatically, but the latch is operated manually to free the bolt, causing the prongs to rotate back into their retracted position.

Figs. 33 and 34 show in further detail the three prongs 134 of socket 150 in an extended position. The prongs are at an angle, 6, of approximately sixty degrees to the platform 36 in this position. As in the other embodiments the prongs 34 are mounted such that they are spaced from each other both along the length of the platform 36 and across its width. The spacing between the prongs means that the shafts attached to each prong also are spaced from each other along the length of the platform 36. This means that the platform only need accommodate the thickness of one shaft, rather than the much greater thickness of three concentric and insulated shafts as in Australian Patent 721095. This allows the platform and so the gap into which the platform is inserted to be relatively thin ie less than 5mm in thickness. In this embodiment the platform no more than 3. 5mm in thickness.

The cross-section of the prongs 34 changes from circular near their base 163 to rectangular near their tip 165 to provide two relatively flat contact surfaces 164. These increase the contact area between the prongs 36 and their respective conductors in the busbar.

Additionally the rectangular cross-sectional portions of the prongs are tapered, to make inserting the prongs into the conductors easier.

Figure 35 shows in more detail the configuration of this embodiment of prong 34, which also is used in the plug of figures 24 to 30. The prong is L-shaped, a relatively short arm 167 of the L providing the contact face, and the relatively long arm of the L providing a shaft 164 for connection to the socket. A cylindrical lever 166 projects from the shaft to facilitate rotation of the prong 162. The prongs of figures 34 and 35 can be used in the other embodiments, which of course are only examples of the many utilizing the principles of the invention.

Figure 36 shows a front housing 168 and a rear housing 170 suitable for containing the conductors around an external corner of a room. The housings are held together by a plurality of clips 172 on the rear housing 170 and clips 174 on the front housing 168.

A slot 176 in the rear housing 170 penetrates almost all the way through the component.

This slot 176 allows for the housing 170 to flex so that if a wall corner is not 90° then the housing 170 can adjust to the angle to the wall corner. The front housing 168 also has a thin section 178 or hinge running down its vertical length so that it may be adjusted to suit the angle of the rear housing 170 of the corner component.

Figure 37 shows a perspective view of a flexible plastic guide 180 which separates the three conductors 90 from each other, and provides guides for the conductors to reduce the tendency for the conductors to kink whilst being placed around the corner. Upstanding flanges 182,184, 186 separate the conductors from each other, and the live conductor from the rear housing 170. Figure 38 shows the rear housing 170 and the flexible plastic guide 180 in situ with an earth conductor 90 and two insulating housings 106,102. This corner installation can, of course, be used with any of the embodiments of the invention, or, indeed, with other such busbar system. A similar arrangement is used for internal corners of the room.

Figure 39 shows a perspective view of an insertion tool used for inserting the conductor (as described above with reference to figures 14 to 15c) into the insulating housing.

The insertion tool 300 comprises an insertion block 302 having a passage 322 running the length of the block for receiving a length or strip of insulating housing 102. The strip of insulating housing is of the type shown in Figures 16 to 16b, that is to say the inner housing component having three channels shaped to receive electrical conductors. The insertion block 302 is mounted on a stand 304 (partially shown) having a base 305 and a number of legs 306.

A drum 310 holding lengths of conductor 314 is rotatably mounted above the insertion

block 302 on a support 308. The drum comprises three separate channels 312 each accommodating a length of conductor to be inserted into strips of insulating housing.

The insertion tool further comprises a flaring assembly 318 for flaring the conductors and insertion head 320 for pushing the flared conductors into the strip of insulating housing 102. Conductors 314 are fed via a roller 316 to the flaring assembly 318 and from there to insertion head 320. Roller 316 is again subdivided into three channels to allow each of the three conductors to be guided accurately into the flaring assembly. Alternatively, separate rollers could be provided.

Between the roller 316 and the flaring assembly 318, the conductors are twisted 90 degrees from the flat orientation in which they are provided on drum 310 to the upright orientation in which they pass through the flaring assembly and into the insulating housing 102.

'The flaring assembly 318 is mounted on a raised platform 326 which is inclined such that the conductors passing through the flaring assembly are directed downwards towards the insertion head 320 and the passage 322 in insertion block 302.

Figure 39a shows a close-up view of the insertion head 320. As can be seen, the passage 322 is shaped to receive and guide the strip of insulating housing 102 and is open at the top beneath insertion head 320. The insertion head 320 is slidably mounted on the insertion block 302 to provide access to passage 322.

Figure 40 shows a close-up view of the flaring assembly 318 of Figure 39. The flaring assembly comprises three profiled discs 340 rotatably mounted between respective supports 342,344. The supports 342,344 are mounted on a base 346 which is fixed to the inclined platform 326 (shown in Figure 39).

The profiled discs 340 are arranged so as to provide passages for the conductors between profiled discs 340, supports 342,344 and base 346 through which the conductors may be passed. To enable the conductors to run closely parallel to each other, the three discs together with their respective supports are provided in a staggered arrangement.

Figure 41 shows a close-up view of one of the profiled discs 340. The disc 340 has a tapered outer portion 350 narrowing towards the perimeter from which a thin rib 352 extends.

The conductor is clamped between two rollers 360,362 mounted for rotation about vertical axes on the base 346 which hold the conductor in place. The rollers 360,362 have respective tapered upper portions 364,366 which correspond to the tapered portion 350 of disc 340. In use, the thin rib 352 and tapered portion 350 of the disc and the tapered upper portions 364, 366 of rollers 360,362 together serve as a rolling die to flare the panels of conductor 314 at

the top, causing them to bend outwardly along the weakened region extending the length of the conductor and which is provided by way of a groove or perforation as described above.

The rollers 360,362 support the conductor against the force of the profiled disc 340, and prevent it being forced downward whilst being flared, which otherwise would jam the mechanism.

Figure 42 shows a perspective view of the insertion head 320 viewed from below. The head comprises three rollers 380,384 and 388 for pushing the conductors into place inside the strip of housing 102. Associated with each roller are respective inclined guide surfaces 382, 386 and 390 and channels 392 for guiding the conductors to the rollers and into the housing.

The guide surfaces 382,386 and 390 also serve as spreaders to open the channels of the insulating housing 102 and thereby enable insertion of the conductors. As can be seen more clearly in Figure 43, which shows a side view of the insertion head 320, the rollers and guide surfaces extend to varying depths below the insertion head corresponding to the varying depths of the channels within the insulating housing.

The insertion head 320 further comprises laterally extending flanges 396 and grooves 398 which cooperate with corresponding flanges on the insertion block 302 (shown in Figure 39) to allow the insertion head 320 to register accurately in the insertion block 302.

Referring back to Figure 39, in use, a strip 102 of insulating housing is inserted into the passage 322 in insertion block 302 in the direction indicated by the arrow. The insertion head 320 is initially partially slid out of the insertion block (as shown in Figure 51), thus providing access to passage 322 holding the strip of housing 102, the passage being open at the top at the head portion of the insertion block. The insertion process is then begun manually by threading the ends of conductors 314 through the flaring assembly and pushing the flared conductors into the channels in the housing 102. The insertion head is then slid back into place. Once in place, the rollers 380,384, and 388 on the underside of the insertion head then extend into the channels in the strip of housing 102 where they can engage the conductors.

The strip of housing 102 is then pulled through the insertion block 302. As the conductors pass under the insertion head, the channels, guide surfaces and rollers in the insertion head serve to guide the conductors into the housing and push them into place.

As shown in Figure 44 (in which some details have been removed for clarity), in a preferred embodiment, insertion block 302 is pivotally mounted on stand 304 to enable it to pivot about axis A. In this way, the orientation of the insertion tool can easily be changed without the need for moving the entire tool. The base 305 of stand 304 comprises a protrusion 402 at each end which cooperates with a corresponding formation 404 on the underside of the

insertion block 302 to hold the insertion block in place in either orientation.

When installing the busbar system into a room, the insertion tool may be used in the following way to provide a busbar with continuous conductors covering multiple wall sections.

First, strips of both the outer and inner insulating housing for the busbar are cut to length depending on the dimensions of the room to provide strips for each straight wall section on which the system is to be installed. The outer housing sections are fixed to the walls of the room. Conductors are installed into the inner housing sections using the insertion tool in the manner described above.

However, rather than cutting the conductor at the end of each strip of housing and reconnecting the conductors once the strips are in place, it is preferable to provide continuous conductors. The conductors are therefore installed continuously into the housing strips by feeding the strips through the insertion tool one after the other, leaving a sufficient gap between adjacent strips to enable the conductor to be bent to fit the corner of the room where the strips are to be installed. Covers are installed in the corners to protect and prevent access to the conductors.

A problem associated with this approach however, assuming the insertion tool is used in situ, is that there is typically not sufficient space to feed each of the strips through in a continuous line, and bending completed strips-which may be several metres long-out of the way may be awkward.

Instead, to simplify the process, the orientation of the insertion tool is therefore inverted (reversed) after each completed strip.

Specifically, once the first strip has been pulled through the tool, the insertion block is swung to its opposite orientation whilst the first strip is held in place. This will bend the conductors exiting the insertion head. In its new orientation, the insertion block will then be parallel to the completed first strip, with the conductors bent back 180 degrees from the insertion head to the completed strip. The second strip is then fed into the insertion block, this time from the opposite direction. When the second strip is pushed and pulled through the insertion block, the completed first strip must then be passed alongside the insertion block in the same direction, since the first and second strips are connected by the continuous conductors. This results in two side-by-side strips with the conductors looping 180 degrees from one to the other. This process is repeated for each strip, thus producing a zig-zag of completed strips. These can then be unfolded for fitting into the corresponding outer housing sections already fixed to the walls of the room.

An alternative embodiment of the insertion tool will now be described with reference to figures 45 to 52, in which like elements are designated with like reference numerals.

Figure 45 shows a perspective view of the alternative embodiment of the insertion tool.

In this, the drum 310 holding the conductors is mounted substantially horizontally on support arm 308 by way of a release mechanism incorporated in handle 424 as will be described below. Base 305 further comprises telescopic portions 420 at each end allowing the length of the base to be varied. A series of support rollers 422 extend sideways out of base 305 to support and transport completed strips of housing built up in the"zig-zag"fashion described above. Except for the outermost ones, the support rollers 422 can be folded away alongside the base 305. The outermost of the support rollers 422 which are attached to the telescopic portions 420 of base 305 can be folded into recesses in the telescopic portions 420 to allow the telescopic portions to be retracted into the base.

Figure 46 shows the insertion tool folded up when not in use. Telescopic portions 420 and support rollers 422 have been retracted, and legs 306 have been folded away. Drum 310 has been removed and support arm 308, which is pivotally attached to the insertion block 302, has also been retracted.

Figure 47 shows an alternative embodiment of the flaring assembly 318 for use with this embodiment of the insertion tool. The flaring assembly differs from that shown in Figure 40 in that the flaring units 440,442 and 444 (comprising respective discs 340 and supports 342, 344) for each of the conductors are mounted at different heights on the stepped base 346 corresponding to the varying depths at which the channels in insulating housing 102 are provided. Respective guide rollers 430 are provided which ensure that the conductors being fed from drum 310 stay aligned accurately with the respective flaring units as the drum is depleted.

One roller 362 of the pair of rollers 360,362 provided in each of the flaring units is adjustable by way of adjusting screws 450 to enable the gap between the flaring rollers to be set, while the other roller in each flaring unit is fixed. For flaring unit 440, the adjustable roller is the one on the opposite side (facing into the page, not shown) for easier access.

Adjusting screws 454 are also provided in each flaring unit to allow the horizontal positioning of the flaring discs 340 to be adjusted. The height of each flaring disc may also be adjusted via four adjusting screws 456 on each flaring unit.

Figure 48 shows a front view of one of the flaring units 440,442, 444. In this embodiment, the rollers 360,362 are flat at the top (and not tapered as shown in the embodiment of figure 41). The extent of flaring is instead limited by plates 462 provided on

the flaring disc 340 either side of the central tapered portion 460.

Figure 49a shows the handle 424 on support arm 308 incorporating the release mechanism for releasably attaching drum 310. The handle is attached to a spring-loaded shaft 480 inside cylinder 486. The shaft 480 is connected to a series of links 482, which are in turn connected to respective rollers 484. In the configuration shown, the rollers extend through apertures in cylinder 486. Lifting the handle 424 retracts the rollers 484 into the cylinder 486 as shown in figure 49b. With the rollers retracted, drum 310 can be placed onto the cylinder 486 as shown in figure 50. When the handle 424 is released, rollers 484 return to their extended positions. The drum 310 can then rest and spin on the rollers 484.

Figure 51 shows the insertion head 320 partially slid out of the insertion block 302 to provide access to the passage 322 and enable manual insertion of conductors into the insulating housing. As in the previously described embodiment, the insertion block 302 is pivotally mounted on base 305 as shown in Figure 52.

This embodiment has generally only been described in terms of the differences to the previous embodiment. Furthermore, aspects of the two embodiments of the insertion tool may be freely combined. Specifically, any of the features of the first embodiment may be incorporated independently of the others or in any suitable combination into the second embodiment and vice versa. For example, any of: the horizontal mounting of the conductor drum, the release mechanism for the drum, the flaring assembly, the flaring units, the telescopic base, and the support rollers of the second embodiment may be incorporated into the first embodiment.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

For example, some reduction in the depth (front to back) of the housing may be achieved if one of the conductors is arranged below the slot then a prong deployed downwardly into it can be in the same lateral position on the platform as a prong deployed upwardly into another conductor.

Further, only one of the conductor panels need be flared outwardly on installation. Then only that panel need have a line of weakness. Again, whilst it is preferred that the prongs are fully recessed into the platform when retracted, in principle they could be only partially recessed, or even lie on the surface of an exceptionally thin platform, so as still to fit in a sufficiently narrow slot in the busbar. The insertion block may be separable from its base,

instead of being pivotally mounted thereon, and thus may be reversed by removing it and replacing it the other way round.

Each feature disclosed in this specification (which term includes the claims) and/or shown in the drawings may be incorporated in the invention independently of other disclosed and/or illustrated features.

Statements in this specification of the"objects of the invention"relate to preferred embodiments of the invention, but not necessarily to all embodiments of the invention falling within the claims.

The text of the abstract filed herewith is repeated here as part of the specification.

An electrical plug for releasable connection to an electrical power and/or communications distribution busbar system, the plug comprising a housing and at least two prongs for electrical connection to respective conductors of the busbar; wherein: the housing has a body and a platform for insertion into the busbar system; and the prongs are mounted to the platform such that they are spaced from each other along and across the platform. The prongs may be moveable between a first position in which they are retained within the platform, and a second position in which they extend out of the platform. In addition, an electrical power and/or communications distribution busbar system includes an elongated electrical conductor which comprises two longitudinally extended panels arranged disposed apart side by side and interconnected by a series of loops along the upper edges, the panels being biased by the loops such that their facing surfaces are generally parallel and/or converging. The conductor can be wound on a drum.