Patent Publication Number: US-7905637-B2

Title: Transformer assembly and light fixture assembly using same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The entire subject matter of U.S. Provisional application Ser. No. 61/024,637 filed Jan. 30, 2008 and entitled TRANSFORMER ASSEMBLY AND LIGHT FIXTURE ASSEMBLY USING SAME is incorporated by reference. The applicants claim priority benefit under Title 35, United States Code, Section 119 of U.S. Provisional application Ser. No. 61/024,637 filed Jan. 30, 2008 and entitled TRANSFORMER ASSEMBLY AND LIGHT FIXTURE ASSEMBLY USING SAME. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO A “SEQUENTIAL LISTING,” A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON A COMPACT DISC 
     Not applicable. 
     FIELD OF THE INVENTION 
     The present invention relates to potted transformers and methods of forming same. 
     DESCRIPTION OF THE RELATED ART 
     Transformers are widely used in power supplies. In some cases, the transformer is “potted” to provide protection and to suppress noise, though there are limitations to current potting techniques. Transformers are commonly used in products such as light fixtures for supplying power to the light source and associated hardware. However, conventional potted transformers are believed to present limitations to some light fixture applications. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Several preferred embodiments of the present invention will be provided, by way of examples only, with reference to the appended drawings, wherein, 
         FIG. 1  is an assembly view of a transformer assembly; 
         FIGS. 2 and 3  are part-sectional side views of the transformer assembly of  FIG. 1 ; 
         FIGS. 4 and 5  are perspective and side views, respectively, of a light fixture employing the transformer assembly of  FIG. 1 ; 
         FIG. 6  is a perspective view of another light fixture employing the transformer assembly of  FIG. 1 ; 
         FIGS. 7 to 9  are perspective operational views of a method of servicing the light fixture of  FIG. 6 ; and 
         FIG. 10  is an operational plan view of a method of servicing the light fixture of  FIG. 6 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It should be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not restricted to physical or mechanical connections or couplings. Furthermore, and as described in subsequent paragraphs, the specific mechanical configurations illustrated in the drawings are intended to exemplify embodiments of the invention. However, other alternative mechanical configurations are possible which are considered to be within the teachings of the instant disclosure. Furthermore, unless otherwise indicated, the term “or” is to be considered inclusive. 
     In one embodiment, there is provided a potted transformer assembly comprising a housing portion to form an exterior transformer housing. A transformer unit is dimensioned to fit within the housing portion. The housing portion includes a first passage to receive the transformer unit in an operative position therein. The housing portion has an inner surface which is oriented to provide an interior cavity between the transformer unit and the inner surface. The interior cavity is dimensioned to receive a predetermined quantity of a potting compound. The housing portion further includes at least one second passage in fluid communication with the interior cavity, the second passage being dimensioned to receive a portion of the potting compound therein. The second passage is located on the housing portion in such a manner that, following a transformer encapsulation step, the presence of potting compound in the second passage is indicative of the transformer being substantially encapsulated by the potting compound. 
     In one embodiment, the inner surface is oriented so that the housing portion is capable of receiving at least two different sizes of transformer units. The inner surface is oriented so that the housing portion is capable of receiving a first transformer unit operable to transform about 50VA of power or a second transformer unit operable to transform about 75VA of power. The housing portion may be formed by a molding or a casting step, such as a die casting step, using an aluminum material for minimizing magnetic vibration noise. 
     In one embodiment, the housing portion includes a closed peripheral side wall portion, the side portion including a first edge region bordering the first passage and a second edge region, an end wall portion joined to the side wall portion at the second edge region, the second passage being centrally located in the end wall portion. 
     In one embodiment, the transformer includes a transformer body with a pair of opposed windings portions extending laterally outwardly from the transformer body, the end wall portion providing a centrally located depression to receive one of the windings portions therein, the second passage being centrally located in the depression. A plurality of guiding members extend inwardly from both the side wall portion and the end wall portion to provide a plurality of shoulder portions to support the transformer body. 
     An embodiment further comprises a gasket member to be located between the transformer body and the shoulder portions, the gasket member and/or the inner surface being dimensioned to provide a plurality of third passages to transfer potting material from the first passage through the inner cavity to the second passage. The housing portion has a plurality of external flanges extending outwardly from the housing, each arranged to receive a fastener therethrough for anchoring the assembly to a light fixture. 
     Another embodiment provides a light fixture comprising a light housing, a power supply assembly to supply power to the light housing and a frame portion supporting the light housing and the power supply assembly, the power supply assembly including a potted transformer assembly including a housing portion to form an exterior transformer housing, a transformer unit dimensioned to fit within the housing portion, the housing portion including a first passage to receive the transformer unit in an operative position therein, the housing portion having an inner surface which is oriented to provide an interior cavity between the transformer unit and the inner surface, the interior cavity being dimensioned to receive a predetermined quantity of a potting compound, the housing portion further including a second passage in fluid communication with the interior cavity, the second passage being dimensioned to receive a portion of the potting compound therein, the second passage being located on the housing portion in such a manner that, following a transformer encapsulation step, the presence of potting compound in the second passage is indicative of the transformer being substantially encapsulated by the potting compound. 
     In an embodiment, the frame portion includes an elongate flexible frame member extending laterally outwardly from the light housing along a first axis, the elongate flexible frame member including a proximal end region joined to the light housing and a distal end region, a junction box mounted to the distal end region. 
     In an embodiment, the elongate flexible frame member includes a first elongate boundary and an opposed second elongate boundary. An expandable channel extends between the light housing and the junction box along the first elongate boundary, the transformer being mounted adjacent the second elongate boundary. 
     In an embodiment, the junction box has a first region lying adjacent the distal end region and a second region lying remote from the distal end region. The junction box has a first surface in the direction of the light housing, the first region having a first dimension aligned with the first axis, the second region having a second dimension aligned with the first dimension. The second dimension is smaller than the first dimension to provide the first surface with a stepped configuration to form a locating region bordered on two sides by the first surface. 
     In an embodiment, the junction box is dimensioned so that the second surface lies adjacent an upper surface of a ceiling panel in an operative configuration, the junction box including a layer of resilient material mounted on the second surface to cushion the junction box in the operative position. In one embodiment, the junction box includes a wall portion adjacent the locating region, further comprising a thermo sensor extending from the wall portion into the locating region. 
     In an embodiment, the transformer unit is located on the flexible frame member and immediately adjacent the junction box. 
     In an embodiment, the junction box has a side wall which is pivotally mounted for movement between a closed position and an open position. 
     Another embodiment provides an arrangement for fabricating a plurality of models of a potted transformer with each model operable for transforming a corresponding level of input power, comprising a group of two or more generic housing portions, a first group of one or more transformer units operable for transforming a first level of input power and dimensioned to fit within the generic housing portions of the group of two or more generic housing portions, a second group of one or more transformer units operable for transforming a second level of input power and dimensioned to fit within the generic housing portions of the group of two or more generic housing portions, each generic housing portion including a first passage to receive a selected transformer unit from the first and second groups in an operative position therein, each generic housing portion having an inner surface which is oriented to provide an interior cavity between the selected transformer unit and the inner surface, the interior cavity being dimensioned to receive a predetermined quantity of a potting compound, the housing portion further including a second passage in fluid communication with the interior cavity, the second passage being dimensioned to receive a portion of the potting compound therein, the second passage being located on the housing portion in such a manner that, after a transformer encapsulation step, the presence of potting compound in the second passage is indicative of the selected transformer being substantially encapsulated by the potting compound. 
     In yet another embodiment, there is provided a method of forming a potted transformer assembly, comprising providing a transformer unit; providing a housing portion with a first passage to receive the transformer unit in the cavity and to receive a quantity of potting compound to encapsulate the transformer unit, the housing portion having a second passage distal to the first passage for egress of the potting compound; depositing the transformer into the cavity through the first passage; depositing the quantity of potting compound into the cavity through the first passage to substantially encapsulate the transformer unit; and inspecting the second passage for the presence of potting compound therein. 
     Yet another embodiment provides a light fixture comprising a light fixture, a power supply assembly to supply power to the light fixture and a frame portion supporting the power supply assembly, the power supply assembly including a potted transformer assembly including a housing portion to form an exterior transformer housing, a transformer unit dimensioned to fit within the housing portion, the housing portion including a first passage to receive the transformer unit in an operative position therein, the housing portion having an inner surface which is oriented to provide an interior cavity between the transformer unit and the inner surface, the interior cavity being dimensioned to receive a predetermined quantity of a potting compound, the housing portion further including a second passage in fluid communication with the interior cavity, the second passage being dimensioned to receive a portion of the potting compound therein, the second passage being located on the housing portion in such a manner that, following a transformer encapsulation step, the presence of potting compound in the second passage is indicative of the transformer being substantially encapsulated by the potting compound. 
     In an embodiment, the frame portion includes a base plate to be substantially parallel with ceiling panel in an operative position, the base plate having an access passage to provide access to the light fixture, the power supply assembly including a junction box adjacent the access passage, the junction box having a pair of opposed side walls, a first proximal side wall and a second distal side wall, the transformer assembly being mounted adjacent the second distal side wall, the junction box including a top wall between the first and second side walls. 
     An embodiment further comprises a mounting plate, the transformer unit being positioned on the mounting plate, the mounting plate having a first edge region with a side wall portion depending therefrom, the side wall being positioned on the top wall. The mounting plate has a second edge region opposite the first edge region, further comprising an anchor lip extending along the second distal side wall to receive the second edge region to retain the mounting plate in position against the second distal side wall. The mounting portion includes a plurality of first anchor formations to engage corresponding second anchor formations on the top wall. The first anchor formations includes passages, the second anchor formations including threaded fasteners extending outwardly from the top wall to receive complementary fasteners secured thereto. The access passage is dimensioned to receive the transformer unit therethough. The proximal side wall is removably mounted on the junction box for manual removal therefrom by accessing the proximal side wall through the access passage. 
     Another embodiment provides a method of servicing a light fixture installation, comprising:
         providing a light fixture with a power supply assembly to supply power to the light fixture and a frame portion supporting the power supply assembly,   providing a base plate with having an access passage to provide access to the light fixture,   providing the power supply assembly with a first potted transformer unit which is dimensioned to pass through the access passage;   providing the power supply assembly with a junction box placed adjacent the access passage, the junction box having a top wall, a removable first side wall which is proximal to the access passage and a second opposed side wall distal to the access passage,   mounting the first potted transformer unit adjacent the second distal side wall, the junction box including a top wall between the first and second side walls;   installing the frame portion between adjacent ceiling joists so that the base plate is substantially parallel with an adjacent ceiling surface,   coupling a light source with the power supply and installing a light source through the access passage in order to operate the light fixture;   and when the first potted transformer unit is to be replaced:   manually reaching through the access passage to a region above the base plate containing the junction box;   removing the first side wall to separate the electrical connections between the first potted transformer unit and the junction box;   accessing the region of the junction box adjacent the top wall or second side wall to disconnect the first potted transformer unit from the junction box,   negotiating the first potted transformer unit through the access passage;   providing a replacement second potted transformer unit;   negotiating the second potted transformer unit through the access passage;   accessing the region of the junction box adjacent the top wall or second side wall to connect the second potted transformer unit from the junction box,   with the first side wall removed, accessing the junction box through the region of to establish an electrical connection between the second potted transformer unit and the junction box; and   removably coupling the first side wall to the junction box.       

     Referring to the figures, particularly  FIG. 1 , there is provided a potted transformer assembly  10  comprising a housing portion  12  to form an exterior transformer housing  14 . A transformer unit is shown schematically at  16  and is dimensioned to fit within the housing portion  12 . The housing portion  12  includes a first passage  12   a  to receive the transformer unit  16  in an operative position therein, as shown in  FIG. 2 . 
     The housing portion  12  also has an inner surface  18  which is oriented to provide an interior cavity  20  between the transformer unit  16  and the inner surface  18 . The interior cavity  20  is dimensioned to receive a predetermined quantity of a potting compound  22  ( FIG. 3 ). The potting compound  22  may be selected while taking into account the dimensions of the inner cavity  20  and the materials used in the forming of the housing portion  12  and the transformer unit  16 , so that that the potting compound  22  is readily bondable with both. For example, suitable potting compounds may be thermoset materials such as those available under the trade names epoxy, acrylic, polyester, silicone and urethane, among other possible materials. 
     The housing portion  12  further includes at least one second passage  12   b  in fluid communication with the interior cavity  20  (as shown by the chain dotted line and arrow  20   a , shown in  FIG. 2 , through the second passage  12   b ). The second passage  12   b  is dimensioned to receive a portion of the potting compound therein along a path according to chain dotted line  20   a  and is located on the housing portion  12  in such a manner that, following a transformer encapsulation step, the presence of potting compound  22  in the second passage  12   a  is indicative of the transformer being substantially encapsulated by the potting compound  22 . 
     The second passage  12   a  provides the benefit of providing the user with a rapid indication of a suitably complete filling of the inner cavity of the housing portion. For instance, where the passage is fully filled, a quality assurance decision may be taken that the housing is fully potted, therefore passing a first stage of a quality review. If, on the other hand, if the second passage  12   b  is not fully filled, that feature alone may be sufficient to reject the transformer assembly  10 . 
     In this particular example, the inner surface  18  is further oriented so that the housing portion  12  is capable of receiving at least two different sizes of transformer units  16 . For instance, the inner surface is oriented so that the housing portion is capable of receiving two or more such transformer units, for instance a first transformer unit operable to transform about 50VA of power or a second transformer unit operable to transform about 75VA of power. This is schematically represented by the additional transformer unit shown at  16 ′ in  FIG. 1 , for a total of two possible transformer units in this example, though more than two may also be provided as desired. 
     In this example, the housing portion  12  is formed by a either molding or a casting step, though other fabrication techniques may also be employed either in conjunction with or as an alternative to molding and or casting, such as by using aluminum, zinc or bronze or other suitable alloys, or plastic materials such as high density polyethylenes. In one example, the housing portion  12  is formed by a die casting step, using an aluminum material for minimizing magnetic vibration noise. 
     The housing portion  12  includes a plurality of guiding members  24  for guiding the transformer unit  16  to a central operable position relative to the interior cavity  20 . The housing portion  12  has a closed peripheral side wall portion  26 , with a first edge region  26   a  bordering the first passage  12   a  and a second edge region  26   b . An end wall portion  28  is joined to the side wall portion  26  at the second edge region  26   b  and the second passage  12   b  is centrally located in the end wall portion  28 . 
     The transformer unit  16  includes a transformer body  16   a  with a pair of opposed windings portions  16   b  extending laterally outwardly from the transformer body  16   a , and two sets of leads  16   c ,  16   d . The end wall portion  28  provides a centrally located depression  28   a  to receive one of the windings portions  16   b  therein ( FIG. 2 ), with the second passage  12   b  being centrally located in the depression  28   a.    
     Referring to  FIG. 1 , the guiding members  24  extend inwardly from both the side wall portion  26  and the end wall portion  28  to provide a plurality of shoulder portions  24   a  to support the transformer body  16   a . A gasket member  30  is located between the transformer body  16   a  and the shoulder portions  24   a . The gasket member  30  has an inner peripheral region  30   a  providing a passage which is dimensioned to receive a corresponding windings portion  16   b . The gasket member  30  and/or the inner surface  18  are, in this case, dimensioned to provide a plurality of third passages  34  coinciding with the path  20   a  to transfer potting compound  22  from the first passage through the inner cavity to the second passage. The gasket member  30  has a peripheral region beyond which extend a plurality of fingers  31 . Each finger  31  is positioned to align with a corresponding guiding member  24 . It will be seen that the gasket member  30 , in the region of the fingers  31 , flexes or bends to substantially isolate the transformer unit  16  from the housing portion  12 , that is with essentially no metal to metal contact therebetween in order that the gasket member  30  can provide some absorption of transformer vibration, thereby acting to reduce the transmission of noise beyond the housing portion  12 . 
     The housing portion  12  may be provided with at least one exterior mounting formation  32  for anchoring the assembly to a light fixture. In this case, the exterior mounting formation includes a plurality of external flanges  32   a  extending outwardly from the housing portion  12 , each flange  32   a  arranged to receive a fastener therethrough (not shown) for anchoring the transformer assembly  10 , as will be described. 
     The transformer assembly  10  may be formed as follows. First, the gasket may be installed on an inward windings portion  16   b  with the fingers  31  oriented to align with the corresponding guiding members  24 . The transformer unit  16  and gasket member  30  subassembly may then be installed though the first passage  12   a  of the housing portion  12  until it comes to rest on the shoulder portions  24   a  of the guiding members  24 . The potting compound  22  may then be poured into the housing portion, over the transformer unit  16  and along the third passages  34  until the potting compound  22  fully covers the windings portion  16   b  adjacent the opening first passage  12   a.    
     Alternatively, the potting compound  22  may be poured into the housing portion  12  to an intermediate level, such as a level approximating the shoulder portions  24   a . The subassembly of the transformer unit  16  and the gasket member  30  may then be inserted in the housing portion  12  with the lower windings portion  16   b  being pressed into the potting compound. Thereafter, the potting compound may be poured into the housing portion, over the transformer and along the third passages  34  until the potting compound fully covers the windings portion  16   b  adjacent the opening first passage  12   a.    
     Thus, the passages  12  may provide an indicator, and in some cases a limited guarantee for an end user that the transformer is fully encapsulated, through substantially the entire housing, thereby providing a quality check point. If the hole is not fully filled, the transformer may be rejected be used to establish to a supplier that the transformer was not property potted, or to show that a potting step is incomplete. If desired, the passage  12   b  may have a width dimension that exceeds the maximum distance between the transformer and the neighbouring portion of the housing portion. 
     The transformer assembly  10  may, for instance, be used as part of a power supply assembly for a light fixture as shown at  40  in  FIGS. 4 and 5 . In this case, the light fixture  40  includes a light housing  42  and a frame portion  44  supporting the light housing  42 , by way of a pair of anchoring flanges  43  and fasteners  43   a  which extend into passages  44   a . The frame portion  44  includes an elongate flexible frame member  46  extending laterally outwardly from the light housing  42  along a first axis “A”. The elongate flexible frame member  46  includes a proximal end region  46   a  which is joined to the light housing  42  and a distal end region  46   b  supporting a junction box  48  mounted thereto. 
     The elongate flexible frame member  46  includes a first upper elongate surface  50   a  (as viewed in  FIG. 5 ) and an opposed second lower elongate surface  50   b . An expandable channel  52  extends between the light housing  42  and the junction box  48  along the first elongate surface  50   a  and provides an inner passageway for power cables between the light housing  42  and the junction box  48 . In this case, the transformer unit  16  is mounted on the second elongate surface  50   b.    
     Referring to  FIG. 4 , the junction box  48  has a first region  48   a  lying adjacent the distal end region  46   b  and a second region  48   b  lying remote from the distal end region  46   b . Referring to  FIG. 5 , the junction box  48  has a first surface  48   c  in the direction of the light housing  42 . The first region  48   a  has a first dimension X 1  extending along an upper span of the junction box, as seen in  FIGS. 4 and 5 , and in line with the first axis A, while the second region has a second dimension X 2  extending along a lower span of the junction box and also inline with the first dimension. In this case, the second dimension X 2  is smaller than the first dimension to provide the first surface  48   c  with a stepped configuration to form a locating region  53  bordered on two sides by the first surface  48   c.    
     The junction box  48  is also dimensioned so that the second region  48   b  lies adjacent an upper surface  54   a  of a ceiling panel  54  in an operative configuration. In this case, the junction box  48  includes a layer of resilient material  56  mounted on the second region  48   b  to cushion the junction box  48  in the operative position. 
     The junction box  48  includes a wall portion  58  adjacent the first surface  48   c , with a thermo sensor  62  extending from the wall portion  58  into the locating region  53 . This provides a convenient location for the thermo sensor  62  so that it is protected and while reducing the overall length of the light fixture that would otherwise occur if the thermo sensor was outwardly extending from the junction box in a direction away from the light housing  42 . 
     The transformer unit  16 , in this case, is located on the elongate flexible frame member  46  immediately adjacent the junction box  48 . The junction box  48  has a pair of side walls  60  which are pivotally mounted for movement between a closed position, shown in  FIG. 5 , and an open position, shown in  FIG. 4 , by way of pivot members  60   a . Thus, the transformer assembly  10  provides a magnetic potted transformer which is particularly useful for light fixture  40 , otherwise known as a downlight frame. The die cast aluminum casing assists to minimize, if not eliminate, magnetic vibration noise. The transformer assembly provides a single casting which can be used for both 50VA and 75VA transformers, among others, as desired. A hole is provided at the bottom of the casing to be indicative that the transformer is sufficiently enclosed by the potting. A gasket is provided between the casing and a mounting plate to minimize noise transfer between the transformer and the casing. 
     The light fixture  40  implements the transformer assembly in one example and also provides a flexible conduit and channel to assist with the orientation of the assembly through ceiling hole and to ensure that that the junction box rests on the ceiling, in this case with no weight or torque being applied to the housing. The junction box is also provided with a gasket which comes into contact with ceiling to minimize, if not eliminate, any stray noise originating from the transformer and emitted through the casing, from transferring to the ceiling. The junction box also provides a pair of opposed covers which are held in the closed position by a spring. Thus, wing nuts or other fasteners are provided to secure the transformer assembly to the junction box to minimize, if not eliminate, vibration or noise transfer. 
     Another exemplified light fixture is shown at  70  in  FIG. 6 . In this case, the light fixture has a light socket portion  72 , a power supply assembly  74  to supply power to the light socket portion  72  by way of a flexible conduit  73  and a frame portion  76  supporting the power supply assembly  74 . In this case, the power supply assembly  74  includes the transformer assembly  10 . 
     The frame portion  76  includes a base plate  78  to be substantially parallel with a ceiling panel  80  in an operative position. The base plate  78  has a peripheral region  78   a  and a number of upstanding walls  82  extending along the peripheral region  78   a . A pair of opposed strut members shown at  84  supports the base plate  78  between a pair of adjacent ceiling joists  80   a . The base plate  78  has an access passage  86  to provide access to the light fixture. The power supply assembly  74  includes a junction box  88  adjacent the access passage  86 . The access passage  86  is thus dimensioned to receive the transformer unit  10  therethrough. 
     Referring to  FIGS. 7 and 8 , the junction box  88  has a pair of opposed side walls including a first proximal side wall  90  and a second distal side wall  92  and includes a top wall  94  between the first and second side walls  90 ,  92 . 
     The transformer assembly  10  is mounted adjacent the second distal side wall  92 . In this case, the transformer unit  10  is positioned on a mounting plate  96 , with a gasket  97  therebetween. The mounting plate  96  has a first edge region  96   a  with a side wall portion  96   b  depending therefrom, the side wall portion being positioned on the top wall  94 . 
     The mounting portion  96  includes a plurality of first anchor formations  98  to engage corresponding second anchor formations  100 , in the form of studs, on the top wall. In this example, the first anchor formations include passages. The second anchor formations include threaded fasteners extending outwardly from the top wall to receive mating fasteners secured thereto, in this example wing nuts shown at  100   a.    
     The mounting plate has a second edge region  96   c  opposite the first edge region. An anchor lip  92   a  extends along the second distal side wall  92  to receive the second edge region  96   c  to retain the mounting plate in position against the second distal side wall. 
     The first side wall  90  has a pair of anchor flanges  90   b  which fit in corresponding grooves  90   c . The first side wall  90  is also removably mounted on the junction box, for example by way of a clip as shown at  90   a , for manual removal therefrom by accessing the proximal side wall through the access passage  86 . 
     Referring to  FIG. 6 , the light fixture  70  may thus be assembled by securing the strut members  84  to a selected pair of ceiling joists  80   a , with the junction box  88  positioned adjacent the base plate  78  and the transformer unit  10  positioned on the junction box  88 . During installation, a reflector (not shown) may be installed through the access passage  86  to receive a lamp (not shown). The lamp may in turn be electrically coupled with the socket portion  72 . 
     The light fixture  70  thus provides a method of servicing a light fixture installation. First, the light fixture  70  is installed in a ceiling  80  with the frame portion  76  positioned to and fastened to adjacent ceiling joists  80   a  so that the base plate  78  is substantially parallel with an adjacent ceiling surface. Next, a light source is coupled with the power supply assembly  74  and then installed in place through the access passage. When the original (or first) potted transformer unit is to be replaced, a user may reach through the access passage  86  to a region above the base plate containing the junction box  88 . As shown in  FIG. 7 , the first side wall  90  may then be removed from the junction box  88  to separate the electrical connections between the first potted transformer unit  10  and the junction box  88 . 
     Next, as shown in  FIG. 8 , the user may access the region of the junction box  88  which is adjacent the top wall  94  or second side wall  92  to dismount the first potted transformer unit  10  from the junction box  88 . The user may then transfer or otherwise negotiate the first potted transformer unit  10  above and over the junction box  88  and down through the access passage  86 , as shown in  FIG. 10 . The user may then select a second potted transformer unit and negotiate same through the access passage  86 . The user may then access the region of the junction box  88  adjacent the top wall or second side wall to fasten connect the second potted transformer unit to the junction box. With the first side wall  90  still removed, the user may then access the junction box through the region of to establish an electrical connection between the second potted transformer unit and the junction box. The user may then removably couple the first side wall  90  to the junction box, by way of anchor clip  92   a.    
     A gasket is also provided between the casing and mounting plate to minimize, if not eliminate, appreciable noise transfer. 
     While the gasket is believed to provided the benefit of additional shock absorption and noise suppression, there may be examples in which there may be other means of providing additional shock absorption and noise suppression, without the gasket member. If desired, the gasket may be formed with different configurations, provided sufficient passages are provided for the potting material to fill the interior cavity of the housing portion, that is to avoid undue obstruction between the guiding members  24 . 
     While the present invention has been described for what are presently considered the preferred embodiments, the invention is not so limited. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.