P/00/009A Section 29 AUSTRALIA Patents Act 1990 INNOVATION PATENT SPECIFICATION Invention Title: A SEALED ELECTRICAL PLUG AND ASSEMBLY Applicant: Spa Electrics Pty Ltd The invention is described in the following statement: 7019 2 A SEALED ELECTRICAL PLUG AND ASSEMBLY The present application is a divisional application from Australian Patent Application No. PCT/AU2007/000758, the entire disclosure of which is incorporated 5 herein by reference. The present invention relates to a sealed electrical plug which has been developed principally for use in underwater lighting and to an underwater light assembly. It will be convenient to describe the invention in relation to an underwater 10 application, however it should be appreciated that the invention has wider application, for example in outdoor lighting such as garden lighting. Underwater lighting is employed in pools, spas, decorative water features, aquariums and in many other installations. A principal requirement of any underwater 15 lighting is the prevention of liquid ingress into the electric componentry of the light. Any ingress of liquid is likely to short the electrical componentry and thus to cause the light to fail. The failure may be repairable, such as by the replacement of a blown globe, or it may be more serious, such that the entire light unit or fixture must be replaced. While either failure is inconvenient, often requiring suitably qualified repair 20 or maintenance personnel, the latter failure can also involve significant expense. It is thus important that the sealing arrangement for underwater lights is effective in protecting the electric componentry from contact with liquid. Because of the critical nature of the sealing for underwater lights, light 25 manufacturers presently manufacture underwater lights with a length of cable connected thereto with the cable being in fully sealed connection with the electrical componentry of the light. By manufacturing the light in this manner, the manufacturer has confidence that the light is properly sealed against ingress of liquid. However, this method of manufacture has disadvantages for installers of lights for pools, spas 30 and other installations. Because the light is already connected to the cable, the installer must install the light at the same time the cable is installed and in many cases this is well ahead of the time when the light is actually required. For example, when a concrete pool is built, the concrete shell is poured first and it is necessary that any electrical cables be positioned within the concrete pour so that the cables extend Z:Su\ABMnnovation patent specs\Spa Electncs Sealed Elecdcal Plug.doc 3 through the concrete shell and so do not have to extend about or around the shell, and so that the concrete sets about the cables, therefore sealing about them. Accordingly, with present arrangements in which the light is already connected to the cable, the light is installed with the cable at the very start of the pool building process. 5 The light then is often left to hang into the concrete shell of the pool while other parts of the pool are constructed, or otherwise the light is placed on the rim of the pool. Regardless, the light often interferes in the pool construction and is prone to accidental damage. 10 Moreover, because lights are installed at an early stage of pool construction, theft of lights often occurs in the days or more likely weeks, before the lights are properly fixed in place. This is most often a problem when the pool is being built as part of a new house. In that case, it is usual that the concrete shell of the pool is poured before construction of the house commences, so that it may be many months 15 in which the lights are susceptible to damage or theft. The applicant has recognised a need to provide an assembly which can enable a cable and plug to be installed when the concrete shell of a pool is poured so that the plug can later be connected to an underwater light. This will permit the light to be 20 connected to the plug at a time suitable for its installation, rather than well ahead of that time. According to the present invention there is provided an underwater light assembly including: 25 a light disposed within a housing and a pair of electrical conductors in electrical connection with the light and extending through the housing, an electrical plug releasably connected to the housing and including a pair of electrical conductors in electrical connection with the electrical conductors connected to the light, 30 an electric lead extending from the electrical conductors of the electrical plug and in electrical connection with the electrical conductors of the electrical plug, a sealing arrangement disposed between the housing and the electrical plug to prevent ingress of water to the connection between the respective electrical conductors of the light and the electrical plug. Z:\S\MD lm ovation patern specs\Spa Electics Sealed Elecical Plug.doc 4 The electrical plug of the assembly advantageously is connectable to the light for supply of electric current to the light. In relation to pools, the electrical plug and lead can be installed at the initial stages of pool construction. They can then remain 5 in place until such time as the pool lights are to be installed. Because the plug is envisaged to be of relatively small size compared to the light to which it is to be connected and because it can be of robust construction and relatively cheap, the plug is much less likely to interfere with the pool construction as compared to a light. Additionally, if the plug does happen to be damaged during pool construction, the cost 10 of replacement will be minor compared to the replacement cost of a light. Further, replacement or repair of a light is a simple matter of disconnecting the plug from the existing light and reconnecting the plug to the new or repaired light. This is advantageous where the light has reached the end of its life, or the light requires maintenance, such as replacement of parts, or if replacement to a new style of light is 15 desired. Thus, the present invention provides a convenient arrangement which eliminates the previous requirement for the actual pool lights to be installed at the initial stages of pool construction, while it also facilitates easy replacement of one light ?0 for another, or for repair of a light. In an assembly according to the invention, the electrical plug can include: first and second connectable parts that define a cavity between them and an inlet into the cavity through which an electrical conductor extends, 25 a pair of electrically conductive members which extend from inside the cavity to positions external of the cavity for electrical connection to an electrical device, the conductive members being connected to the electrical conductor which extends into the cavity through the inlet, a seal within the cavity and extending about the conductive members, the seal 30 including an opening for sealing about the electrical conductor which extends into the cavity. Z:\S\ABMunhovation patent specs\Spa Electrics Sealed Elecrical Plug.doc 5 The inlet through which the electrical conductor extends can be provided in one of the first and second connectable parts, or can be provided through a portion of each of those parts. 5 The seal can be located relative to at least one of the first and second connectable parts, and is preferably located within a recess. Moreover, the seal and at least one of the first and second connectable parts can cooperate by a tongue and groove arrangement in which a tongue extends into the groove to assist sealing between the seal and the respective connectable part. Such a tongue and groove 10 arrangement can be provided between the seal and each of the connectable parts. A tongue and groove arrangement can also exist between the external surface of the seal about the seal opening and the inlet of the electrical plug to likewise assist sealing between the seal and that inlet. 15 In each of the tongue and groove arrangements discussed above, the seal can include the groove and that the connectable part or parts include the tongue. The connectable parts can be connected together in such a manner that as ?0 they are connected, the seal is at least slightly compressed between the connectable parts. Compression of this kind can also assist to locate the tongue within the groove of any tongue and groove arrangements which are provided. The opening in the seal through which the electrical conductor extends, can be 25 sized to fit about the electrical conductor frictionally. The size should be sufficient that the electrical plug can be pushed through the opening, but when the electrical conductor is properly positioned relative to the seal, the seal frictionally grips the electrical conductor for resistance to ingress of liquid into the cavity into which the electric conductor extends. 30 The pair of conductive members can extend through only one of the first and second connectable parts. The conductive members are exposed externally of the respective connectable part for connection to an electrical device. This exposure can be provided by the conductive members extending beyond the outer surface of the Z:u\BMWInnorvabon patent specs\Spa Elecest Seated Electical Plug doc 6 connectable part, or it can be provided by the conductive members extending to a position which can be accessed by connections of the electrical device. For example, the exposed portion of the conductive members may be positioned within a recess and surrounded by a seal, but still be accessible for connection to an electrical device. 5 The conductive members can be formed as posts, with a head portion exposed externally of the conductive part through which they extend. It is to be appreciated that there can be more than a pair of conductive members if required. Thus, any suitable number of conductive members can be employed. 10 The conductive members can include a clamping arrangement on a portion thereof that extends into the cavity, to clamp an electrical conductor thereto. In some arrangements, the conductive members are posts and include a threaded end internally of the cavity, and one or more nuts can be threaded onto the threaded end to clamp the electrical conductor thereto. Alternatively, the electrical conductor can 15 include a threaded end for threaded engagement with the post ends. The portion of the conductive members which is exposed externally of the electrical plug for electrical connection to an electrical device can be associated with a seal arrangement which extends about each external portion of the conductive ?0 members. In some arrangements, a pair of annular seals are provided, each of which is disposed about the respective external portion of each conductive member. This seal arrangement can be located in the connectable part through which the conductive members extend and a recess can be provided in the respective connectable part to locate the seals. This seal arrangement can cooperate with the 25 respective connectable part, through a tongue and groove arrangement like those discussed earlier. The seal arrangement discussed above is intended to cooperate with the electrical device to which the sealed electrical plug is attached. Accordingly, the seal 30 arrangement is intended to be compressed between the electrical device and the sealed electrical plug when connection between them is established and it is appropriate that the electrical device include a suitable cooperating arrangement to ensure proper sealing between the seal arrangement and the electrical device. As in Z:%SABMlnno2vation patent specs\Spa EleIds Sealed Eledical Plug doc 7 earlier embodiments, the electrical device can include a tongue or groove for cooperating with a respective groove or tongue of the seal arrangement. The cavity of the electrical plug can be filled with a filler substance to further 5 enhance the resistance to liquid penetration to within the cavity. In one arrangement, the electrical plug includes a filler inlet, through which the filler substance can be injected into the cavity. A filler outlet can also be provided, for egress of air from within the cavity as the filler substance is being injected. It is to be noted that egress of air from within the cavity is unlikely to occur other than through a filler outlet, given 10 that when the filler substance is being injected, the electrical plug will be substantially sealed against ingress or egress of liquid. The filler inlet and, if provided, the filler outlet, can be closed by any suitable arrangement, such as by screws which are screwed into the inlet and outlet when the cavity has been fully filled. The screw heads can cooperate with a suitable seal, such as an O-ring seal when they have 15 been fully screwed into the closed position. The filler substance can be any suitable substance, but applicant has preferred the use of lanolin, given its ready availability, ease of injection and advantageous sealing properties. 20 Where a filler substance is employed, the electrical conductor can be positioned in place in the electrical plug before the filler substance is injected. Advantageously, the arrangement which includes a filler inlet and outlet allows the electrical plug to be fully assembled with the conductor in place, so that the last step 25 in the assembly process is to inject the filler substance. Because the sealed electrical plug is intended to be left exposed for short to long periods prior to connection thereto of an electrical device such as a light, the plug can include a removable sealing cover for covering the exposed portions of the 30 conductive members against contact with liquid. The cover can simulate connection with an electrical device, so that, in the arrangement in which seals are disposed about the exposed portions of the conductive members, the cover can engage those seals and thus isolate the exposed portions from exposure to liquid. The cover can be formed as a plate which is connected to the electrical plug in the same manner as Z:Su\ABM ,lnoaion palen spec\Spa Elecides Sealed Electdical Plug doc 8 the electrical device is connected to the plug so that where the plug is connected to an electrical device via a plurality of screws, the cover can employ screw openings at the same positions as such openings are provided in both the plug and the electrical device. The cover can include one or more tongues for entry into grooves provided in 5 seals which extend about the exposed portions of the conductive members. It is envisaged that in many cases, the electrical plug will be manufactured with the electrical conductor already attached and therefore the sealed electrical plug of the above described kind can include an electrical conductor which is connected to 10 each of the pair of electrically conductive members of the plug. The conductor would normally be in the form of an electric cable, although it could take other forms, such as a conductive rod, bar or socket. The manner in which an electrical plug can be constructed normally would 15 involve the following steps. The electrical conductor would be passed through the opening in the seal and the conductor would be connected to each of the pair of electrically conductive members. The first and second connectable parts would then be connected together with the seal being operable to seal between those parts and to seal about the pair of electrically conductive members, the electrical conductor and 20 the inlet of the electrical plug. If provided, screws closing the filler inlet and outlet can be removed and a filler substance injected into the cavity between the first and second connectable parts. The sealed electrical plug is thus ready for installation, such as in the concrete pour of a new pool. 25 The electrical plug remains ready for connection to an electrical device thereto and when ready, if a cover is provided over the exposed portions of the electrically conductive members, the cover is removed and the electrical device is attached. For a better understanding of the invention and to show how it may be 30 performed, embodiments thereof will now be described, by way of non-limiting example only, with reference to the accompanying drawings. Figure 1 is an exploded view of a sealed electrical plug according to the invention. Z:\SuBMmrov action patent specs\Spa Electncs Sealed Electrcal Plug.doc 9 Figures 2 and 3 are further exploded views of a sealed electric plug according to the invention. 5 Figure 4 is a part view showing components of the sealed electrical plug of Figures 1 to 3. Figure 5 is an assembled view of a sealed electrical plug of Figures 1 to 3. 10 Figure 1 is an exploded view of a sealed electrical plug 10 which is to be connected to an electrical device 11, which is in the form of an underwater pool or spa light. The light 11 includes a housing 12 within which is disposed the workings of a light, and part of those workings include electrical connectors 13 which extend through a wall 14 of the housing 12 and into the interior 15 of the housing 12. The 15 arrangement of the connectors 13 and the light contained within the housing 12 is not important in relation to the present invention and therefore will not be described further. Referring to the plug 10, this is shown in greater detail in Figures 2 and 3, 20 which also show the plug in exploded view. The plug 10 includes a first connectable part 20 and a second connectable part 21. A seal 22 is shown disposed between the first and second connectable parts 20 and 21. The seal includes a portion 23 for extending about a pair of electrically conductive members or posts 24, 25 and an inlet portion 26 for positioning in an inlet formed between the first and second connectable 25 parts 20, 21. The seal 22 defines an opening 27 in the inlet portion 26 and it is through the opening 27 that an electrical conductor 28 in the form of an electric cable (see Figure 1) can extend. The inlet of the electrical plug 10 is formed between the first and second connectable parts 20, 21 by the inlet portions 29 and 30. The second connectable part 21 includes a recess 32 to accept the seal portion 23. The recess 30 32 follows the same shape as the seal portion 23 and is a neat or snug fit about the seal portion 23. While not shown in the figures, the base 33 of the recess 32 can include a projecting tongue, and the facing surface 34 (see Figure 2) of the seal portion 23 can include a groove, to form a tongue and groove cooperating engagement between the seal portion 23 and the recess 32. The tongue and groove ;S\AZ 8Mnnovation patent specs\Spa Electdcs Seated Elecidca Plug.doc 10 arrangement can extend for the full extent of the seal portion 23 and into the wings 35 on opposite sides of the inlet portion 26. The seal portion 23 engages against an abutment surface 36 of the first 5 connectable part 20, which surface 36 is formed to the same shape as the seal portion 23. It is appropriate that the abutment surface 36 also include a projecting tongue for receipt within a groove formed in the surface 37 (see Figure 3) of the seal portion 23. It will be readily apparent that while it has been described that the seal portion 23 can include a groove on opposite surfaces 34 and 37 thereof, it is equally 10 applicable that a tongue be provided on those seal surfaces, or a tongue on one surface and a groove on the other and that complementary groove and tongues be provided on the base 33 and the abutment surface 36 of the respective connectable parts 20, 21. 15 The conductive posts 24 and 25 extend through openings 40 in the second connectable part 21 and into a cavity which is created between the parts 20 and 21 when they are connected together. An electric cable 28 which extends through the opening 27 of the seal 22 and into the cavity, can be connected to the conductive posts 24 and 25. It is apparent from the figures that the conductive posts 24 and 25 20 are threaded and thus, a clamping arrangement in the form of a pair of threaded nuts 41 can be employed to clamp the electric cable 28 to the posts 24, 25. The head of the openings 40 is hexagonally shaped complementary to the heads 42 of the conductive posts 24, 25. The heads 42 are intended to form an 25 electrical abutment for connection to the connectors 13 (Figure 1) of the electrical light 11. The shoulders 43 of each post 24, 25 are arranged to abut against an 0-ring seal 44 which is disposed within the openings 40. Recesses 45 are formed about the heads 42 of the conductive posts 24, 25, to accommodate annular seals 46 and the annular seals 46 are intended to cooperate firstly with a cover 47 and later with the 30 surface 48 (see Figure 1) of the wall 14 of the light 11. The cover 47 is fixed to the second connectable part 21 by a plurality of screws 50 (see Figure 1), that extend through three openings 49. The cover 47 can include any suitable arrangement to seal with the seals 46, and again, a tongue and groove arrangement can be employed for that purpose. Advantageously, the three screw connections that fix the Z:&MBMUnnovation patent specs\Spa Elecincs Sealed Elecdbcal Plug doc 11 cover 47 to the second connectable part 21, can also be employed, when the cover 47 is removed, to connect the plug 10 to the light 11. Referring to Figure 1, screws 50 extend through each of the first and second 5 connectable parts 20, 21 and into threaded engagement with the cover 47. When the cover 47 is removed, the same screws 50 screw into connection through openings in the wall 14 of the light 11. Screws 51 are employed to fasten the first connectable part 20 to the second 10 connectable part 21, while two further screws 52 are provided for extension into filler inlet 53 and filler outlet 54. The filler inlet 53 permits injection of a filler substance, such as a lanolin, into the cavity formed between the first and second connectable parts 20, 21 and evidence of the cavity being filled is provided when the filler substance starts to leak out of the filler outlet 54. When that occurs, the screws 52 15 can be screwed into the inlet and outlet 53, 54 to maintain the filler substance within the cavity. It is expected that the method of manufacture of the plug 10 would involve insertion of the cable 28 through the opening 27 of the seal 22 and thereafter, the 20 cable 28 can be attached to the ends of the posts 24, 25 which project through the second connectable part 21. When that connection has taken place, the first and second connectable parts 20, 21 would be connected via screws 51, and the connection preferably is such that the seal 22 is compressed between the two parts 20 and 21. Thereafter, a filler substance can be injected into the plug 10 through the 25 inlet 53 until such time as the substance starts to leak out of the filler outlet 54. At that time, screws 52 can be inserted into the inlet and outlets 53 and 54. Finally, the cover 47 can be attached by way of the screws 50 and following that attachment, the plug 10 is ready for installation. 30 Instead of connecting the cover 47 to the plug 10, it would be appropriate in some circumstances, to connect the light 11 directly to the plug 10 if the light 11 is ready for installation. It is therefore optional as to whether the cover 49 is employed or not. Z:\S\BM\nnovabon patent spec\Spa Elecbcs Sealed ElecMcal Plug.doc 12 Figure 4 illustrates the second connectable part 21, with the conductive posts 24, 25 extending therethrough and the seal 22 fitted into the recess 32. Figure 5 shows the sealed electrical plug 10 in an assembled form, with the 5 cable 28 fitted thereto. The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall 10 within the spirit and scope of the above description. Z:\\ABM\lnnovaon patent specs\Spa Elecidcs Sealed Electdcal Plug doc