Patent Publication Number: US-7210826-B2

Title: Component tray for electrical fixture housing

Description:
FIELD OF THE INVENTION 
   The invention relates generally to housings for electrical fixtures and, more particularly, to a system for securing a ballast in such a housing. 
   BACKGROUND OF THE INVENTION 
   Many lighting systems use lamps which are powered by electrical and/or electronic circuits that include transformers for changing a line voltage to meet the needs of a particular type of lamp(s) being powered. Such transformers may be identified simply as being “ballasts,” although that term may also refer to the entire circuit being used to power the lamp(s). In a lighting fixture, a ballast can also assist in regulating power. For example, when such a ballast is used in conjunction with a capacitor, a power factor of the circuit is controlled. When a ballast transformer is used, for example, in an HID lighting application, the transformer may act as an inductor for limiting power. Conventional ballasts often use an open core and coil construction, in which a core of laminated steel, iron, or similar material has wire windings. 
   Lighting fixtures create heat as a result of its lamp(s) converting electrical energy into light. The heat inside such a lighting fixture is made greater when a ballast is also included inside the lighting fixture housing because the ballast also consumes energy and generates heat. Heat can be very damaging to lighting components, causing compromised performance or failure. It is therefore important to reduce the amount of such heat inside the lighting fixture in order to extend the life of the various lighting fixture components, for safety, and for other reasons. For example, a failing ballast can get extremely hot and become a fire hazard. While some ballasts include a safety device which shuts the ballast off in case of extreme thermal conditions, such safety devices are not infallible and, in any event, such problems may be reduced by simply reducing the heat within the fixture. 
   It is known to transfer heat from the ballast to the lighting fixture housing for dissipating such heat. For example, a double-wall ballast engagement and ballast mounting method is disclosed in U.S. Pat. No. 6,867,959, incorporated herein in its entirety and having the same assignee and inventors as the present invention. The &#39;959 patent discloses a housing where screws are used for directly attaching the ballast to two walls of the fixture. However, such a structure is not adapted for easily servicing the lighting fixture, such as when it becomes necessary to replace any of the various components of the ballast circuit. There is a need for a lighting fixture that provides for transferring heat from the ballast while also providing for ease of ballast circuit servicing. 
   OBJECTS OF THE INVENTION 
   It is an object of the invention to provide an improved electrical fixture housing overcoming some of the problems and shortcomings of the prior art, including those referred to above. 
   Another object of the invention is to provide an electrical fixture housing having a component tray adapted for easy servicing of an enclosed ballast circuit. 
   Another object of the invention is to provide a component tray for electrical fixtures where a ballast mounted on the component tray is positioned for efficient heat transfer between at least one side of the ballast and at least one wall of the fixture housing. 
   Still another object of the invention is to provide a component tray for electrical fixtures that provides snug engagement of a ballast and two walls of an electrical fixture housing by use of an urging mechanism for positioning the component tray in the housing. 
   Yet another object of the invention is to provide a component tray for electrical fixtures that is configured for either of a closed position forcing a ballast snugly against at least one wall of a housing and an open position semi-detaching the tray from the housing for servicing the component tray. 
   Another object of the invention is to provide a configuration for a component tray of an electrical fixture whereby the component tray swings into or out of a position of snug engagement of a ballast with at least one wall of a housing of the electrical fixture along an arc-shaped path. 
   Another object of the invention is to provide apparatus for first positioning a ballast tray in a location where adjacent walls of a ballast become close to corresponding walls of a heat sink, and then snugly fastening the ballast against the heat sink so that maximum heat transfer takes place between the two ballast walls and the heat sink. 
   Another object of the invention is to provide a method of snugly seating a ballast against heat sink wall(s) of an electrical fixture, where a self-adjusting attachment structure allows the ballast to be fastened into flush abutment with the heat sink wall(s) or unfastened to be easily moved to a servicing position. 
   Another object of the invention is to provide a component tray for lighting fixtures that is adapted for easy servicing and for snugging a ballast of the component tray against a heat sink surface of a housing of the lighting fixture, with a self-adjusting of the snugging mechanism. 
   How these and other objects are accomplished will become apparent from the following descriptions and drawing figures. 
   SUMMARY OF THE INVENTION 
   According to an aspect of the invention, in a housing for electrical lighting fixtures, the housing of the type enclosing ballasts, the housing including top and rear walls and first and second side walls, an improvement includes a ballast being secured to a component tray and being directly and snugly engageable with at least one heat sink surface of the housing by a quickly-detachable attachment of the component tray to the first and second side walls. 
   According to another aspect of the invention, an assembly is disclosed for an electrical fixture housing, the housing of the type enclosing ballasts, the housing including top and rear walls, first and second side walls, and at least one heat sink pad, the assembly including a component tray having a longitudinal axis between first and second ends, a middle portion, and a ballast secured to the middle portion, and, first and second tray attachments structured for quickly-detachable attachment of the respective first and second ends of the component tray to the respective first and second side walls of the housing, where the attachment effects direct and snug engagement of the ballast with the at least one heat sink pad. 
   According to a further aspect of the invention, apparatus includes a housing for electrical lighting fixtures, the housing of the type enclosing ballasts, the housing including two heat sink pads, a ballast tray having a ballast disposed thereon, hinge means for moving the ballast tray to and from a position of snug engagement with the two heat sink pads, and fastening means for securing the ballast tray to the housing. 
   According to another aspect of the invention, a method of engaging a ballast of a component tray with at least one heat sink surface of an electrical fixture housing, includes swinging the ballast to a position proximate and essentially parallel to the heat sink surface, and snugging the ballast against the heat sink surface by fastening the component tray to the electrical fixture housing. 
   As a result of various implementations of the invention, an improved construction of an electrical fixture overcomes certain problems of the prior art by providing optimized heat sinking for ballast transformer(s) of the electrical fixture, while also providing improved serviceability for a ballast circuit of the fixture that includes the ballast transformer. 
   The foregoing summary does not limit the invention, which is instead defined by the attached claims. 

   
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       FIG. 1  is a perspective view of a lighting fixture having a component tray adapted for servicing of components disposed thereon, according to an exemplary embodiment of the invention. 
       FIG. 2  is a perspective view of a bare unloaded component tray adapted for having a ballast transformer and associated ballast type components attached thereto and adapted for installation into a lighting fixture of a type having lamp(s), ballast(s), and a housing, according to an exemplary embodiment of the invention. 
       FIGS. 3A–3C  are respective top, side, and end views of the component tray of  FIG.2 . 
       FIG. 4  is a fragmentary view of a hinge portion of the lighting fixture of  FIG. 1 . 
       FIG. 5  is a fragmentary view of an exemplary mounting structure for mounting an attachment rod of the hinge portion to a side wall area of the housing of the lighting fixture of  FIG. 1 . 
       FIGS. 6A–6C  are respective perspective views of the lighting fixture of  FIG. 1  in successive stages of opening the component tray of the lighting fixture for servicing, according to an exemplary embodiment of the invention. 
       FIG. 7  is a perspective view of the lighting fixture of  FIG. 1  showing the component tray of the lighting fixture in a fully closed and fastened position. 
       FIG. 8  is a fragmentary cross-sectional view of  FIG. 6B , looking toward a fastening end of the lighting fixture of  FIG. 1  and showing a relation between heat sink surfaces and the ballast of the component tray of the lighting fixture. 
       FIG. 9  is a fragmentary cross-sectional view of  FIG. 6A , looking toward a fastening end of the lighting fixture of  FIG. 1  and showing a relation between heat sink surfaces and the ballast of the component tray of the lighting fixture. 
       FIG. 10  is a highly schematic view of an arc-shaped line of travel of a ballast transformer being placed into a snug abutment with two orthogonally disposed heat sink surfaces, according to an exemplary embodiment of the invention. 
       FIG. 11  is a highly schematic view of a tightening of a ballast against two orthogonally disposed heat sink surfaces when a component tray holding the ballast is fastened against a portion of the housing of a lighting fixture, according to an exemplary embodiment of the invention. 
       FIG. 12  is a perspective view of a housing for a lighting fixture according to an exemplary embodiment of the invention. 
       FIG. 13  is a cross-sectional view of a component tray of a lighting fixture having a short ballast installed in the tray and having a height-extending portion attached to an end of the ballast, according to an exemplary embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  is a perspective view of a lighting fixture  10  of a preferred embodiment. A ballast tray  20  is shown having a hook  21  that is being lifted over and dropped onto a mounting rod  31  that is secured to a portion of the housing  40 . Ballast tray  20  is adapted for mounting a ballast transformer  50  thereon. Ballast transformer  50  has opposite long-dimension surfaces  51 ,  53  and a top surface  52 . When hook  21  is placed onto rod  31 , ballast tray  20  hangs from rod  31  and may be swung up into housing  40  by pushing up on the distal end  28  of ballast tray  20 . When distal end  28  of ballast tray  20  is thus moved into position, a shaft  61  of a fastening portion  60  is placed into a notch  26  of fastening end  28 , whereby an angled portion  27  of fastening end  28  is caused to be held up by a fastening surface  62 . A knob  63  is threaded onto shaft  61 , so that when knob  63  is turned, fastening surface  62  is urged against an outside surface of angled portion  27  and ballast tray  20  is thereby pressed up and into housing  40 . In particular, such installation of ballast tray  20  into housing  40  causes top surface  52  of ballast  50  to be pressed against an upper heat sink pad  42 , and causes rear-facing long-dimension surface  53  of ballast  50  to be pressed against a rear heat sink pad  43 . Preferably, ballast  50  and ballast tray  20  are configured so that surfaces  52 ,  53  of ballast  50  are respectively parallel with heat sink pads  42 ,  43  when ballast tray  20  is in the closed and fastened position, thereby optimizing a transfer of heat from ballast  50  to housing  40 . 
   A ballast  50  may have an “open core and coil” construction, in which a core of laminated steel, iron, or similar material has windings of coils of wire. An exemplary ballast transformer suitable for preferred embodiments is an autotransformer ballast available from Advance Transformer Co. of Rosemont, Ill. and has a part number 71A6091A. A dry film capacitor is used in series between the secondary of such a transformer and a lamp (not shown), the capacitor also being available from Advance and having a part number 7C240P40-R. Such a capacitor is shown with a reference character  57  and is secured to ballast tray  20  with a capacitor holder  22 . 
   Typical housings for electrical lighting fixtures are constructed from aluminum, steel, composites or other metals and are commonly designed in view of size concerns as well as a variety of factors including separation of the ballast from other heat-sensitive components, aesthetic appeal, etc. Rear heat sink pad  43  is preferably fully attached to housing  40  around at least three of its four perimeter sides, thereby distributing heat from heat sink pad  43  to adjacent heat conductive portions of housing  40 . 
     FIG. 2  is a perspective view and  FIGS. 3A–C  are respective top, side, and end views of a component tray  20  according to an exemplary embodiment. A wire routing hole  24  is provided on a top surface  25  of ballast tray  20  for passing wires (not shown) therethrough, such as for electrically connecting primary windings of ballast transformer  50  with a line voltage and connecting secondary windings of ballast transformer  50  together with leads from capacitor  57  and a lamp socket (not shown), etc. Various other components may be mounted to component tray  20 , such as power transistors and other heat-generating components, capacitors and other non-heat-generating components, etc. The components may include a starter/ignitor (not shown) which may include electronic components in a small case, acting, for example, to increase lamp voltage from approximately 280 VAC to approximately 3000 volt pulses, for a short time until a lamp strikes. After the lamp strikes, in this example, the starter deactivates and normal 280 VAC operation resumes. A grounding terminal hole  35  is provided in top surface  25  of ballast tray  20  for attachment of a grounding terminal (not shown) in order to connect earth ground of an electrical service. Opposing rear mounting holes  36  are provided on a rear transformer mounting bracket  33  and front mounting holes  37  are provided on a front transformer mounting bracket  34 , for mounting ballast  50  to ballast tray  20  using two long machine screws  32  or the like that pass through corresponding holes  54 ,  55  formed in ballast transformer  50 . A nut plate (not shown) or the like is preferably used for securing ballast transformer  50  to ballast tray  20 , whereby threaded holes of the nut plate are engaged by machine screws  32 , causing ballast transformer  50  to be tightly secured against the inside surface of brackets  33 ,  34 . Distal ends of screws  32  pass through the opposite holes  36 ,  37  of the respective hole pairs to provide additional structural integrity. 
   In the exemplary embodiment of  FIG. 3C , three separate pairs of ballast front mounting holes  37  are provided. This allows one of a number of different size ballasts to be selectively installed in component tray  20  for various different applications. For example, the illustrated configuration of tray  20  provides for three different ballast lengths, shown as respective distances between mounting hole  36  and one of the three mounting holes  37 . Any width less than or equal to the maximum width distance, between the pair of rear transformer mounting brackets  33  along rear tray wall  76 , may be used. Any ballast transformer height less than or equal to the maximum height, for example the distance between ballast tray  20  and rear heat sink pad  43  when tray  20  is in a fastened-down state, may be used. 
     FIG. 13  shows an alternative embodiment where a ballast transformer  150  has a short height. An extension  151 , formed of a metal having a high heat conductivity, is attached to a bottom surface of ballast transformer  150 , the overall total height of ballast  150  with the added extension  151  is approximately the same as the height of ballast transformer  50 . Extension  151  may be a conductive spacer, a set of bracket(s) for attaching ballast  150  at a distance from the inside surface of ballast tray  20 , or the like. As a result, when ballast tray  20  is fastened in place, a top surface  152  of ballast  150  engages rear heat sink pad  142  in the same manner as when ballast transformer  50  is used, so that heat of ballast transformer  150  is transferred to heat sink pad  142 . It is also possible to use a shorter transformer  150  without using extension  151 . In such a case, only a long side  153  of ballast transformer engages a heat sink surface  143  of housing  140 , and heat sink pad  142  is not used for heat conduction. A smaller transformer  150  generally produces less heat and the use of only one surface for heat sinking may be acceptable. 
   Ballast tray  20  is formed with hook  21  being angled away from a rear tray portion  76  to a front tray portion  77 . That is, an acute angle A is formed between the longitudinal axis  70  of tray  20  and a longitudinal axis  71  of hook  21 . In  FIG. 4 , a rod  31  having a longitudinal axis  81  is shown mounted near a rear corner of housing  40  using rear rod mounting bracket  47  and front rod mounting bracket  48 . An acute angle X is formed between rod longitudinal axis  81  and tray longitudinal axis  70  when component tray  20  is installed. As shown in  FIG. 5 , rod  31  is mounted onto a rear post  45  and a front post  46  of housing  40 . Front post  46  extends to a distance further from a well portion  49  of housing  40 , compared with rear post  45 . This height difference of posts  45 ,  46  causes rod  31  to be tilted towards the rear of housing  40  and toward rear heat sink pad  43 . In an alternative embodiment, shown by example in  FIG. 12 , a rod bracket  96  is a cast unitary structure that provides another way of mounting rod  31 . 
   The amount of tilt is shown as an angle Z between a plane  83 , normal to rear heat sink pad  43 , and rod longitudinal axis  81 . Although not mandatory, angle Z is preferably from one to ten degrees. Since the combination of the individual orientations of components of fixture  10  is designed to achieve a positioning of a ballast  50  in a location where a side  53  of ballast  50  is essentially parallel and in close proximity to a heat sink pad  43 , angle Z may be selected to be zero or greater than ten degrees, but a corresponding alteration may then be necessary for other dimensions of the fixture. Since angle X causes tray  20  to swing away from heat sink pad  43  when tray  20  is being lowered away from its attached location, angle Z allows the arc of travel of tray  20  to have a two-dimensional nature, whereby tray  20  simultaneously rotates while moving in a downward angle. 
   As a result of angles A, X, and Z, tray  20  may be caused to swing away from rear heat sink  43  when ballast tray  20  is being swung down or when ballast tray  20  is being closed into housing  40 , as shown in  FIGS. 6A–6C . For mounting rod  31 , the combination of angles X and Z allows a directionality of ballast tray travel into the heat sink “corner” of the housing formed by the intersection of heat sink pads  42 ,  43 . In particular,  FIG. 10  shows an arc of travel for a long side  53  of ballast transformer  50  as it is placed into position by closure of ballast tray  20 . This is also shown by  FIGS. 8 and 9 , respective cross-sectional views of  FIGS. 6B and 6A  in successive stages of such closure. The arced travel acts to prevent interference of ballast tray  20  and its various components with portions of housing  40 . The arced travel is optimized by the specific angles A, X, and Z, so that long side  53  of ballast transformer  50  is positioned to be essentially parallel with heat sink pad  43  at a position where fastener  60  is engaged with fastening end  28  of ballast tray  20 . 
   At the fastening end  28  of ballast tray  20 , an angle B is formed between the tray longitudinal axis  70  and a plane  72  of angled portion  27 . When fastening shaft  61  is placed into notch  26  of tray  20 , fastening surface  62  is caused to rest atop a fastening surface  30  of angled portion  27 . Fastening shaft  61  is arranged to be approximately orthogonal to fastening surface  30  when shaft  61  is engaged with notch  26 . That is, the attachment and length of shaft  61  causes shaft  61  to be approximately perpendicular to plane  72 , in two dimensions. However, shaft  61  is also angled from rear to front of housing  40 , which causes ballast tray  20  and long ballast side  53  to be pulled toward rear heat sink pad  43  when knob  63  is tightened down. The tightening of knob  63  also causes ballast tray and long ballast surface  53  to be forced tighter against top heat sink pad  42 . Thereby, ballast transformer  50  is tightened in a manner where it is forced into the heat sink corner. 
   The tightening of knob  63  further causes a longitudinal stretching force to be exerted on tray  20  due to the force of fastening surface  62  on fastening surface  30 . This longitudinal force acts to slightly bend tray  20  and pull against mounting rod  31 , there being at least some elasticity in tray  20  for a slight springing action. A tray stop  99  is formed on an interior surface of housing  40  near fastener  60 . Tray stop  99  is dimensioned for abutting a top surface (ballast side surface) of ballast tray  20  near fastening end  28 , when ballast tray is in the fastened position of  FIG. 7  and knob  63  has been fastened to a predetermined point. At the abutment point, knob  63  is able to be further turned to increase the fastening force of fastening surface on angled portion  27 . As knob  63  is further tightened to force ballast tray  20  against tray stop  99 , the tightening of knob  63  becomes increasingly more difficult until a point is reached where additional tightening requires great strength and would not be attempted by the service person or installer. At such a point, the deformation or slight stretching of tray  20  caused by the force of fastening surface  62  on angled portion  27 , and the orthogonally-oriented force on tray  20  caused by tray  20  being deformed by being over-tightened against the already-snugged ballast  50 , are each limited by tray stop  99 . Such a state causes ballast tray  20  to be securely fixed at each end and by additional fulcrums established by the aforementioned tray stop  99  and ballast  50  each pushing against middle portions of tray  20 . Such use of ballast  50  and tray stop  99  adds additional locations that act as spring members with respect to tray  20  and that contribute to the self-adjustment of tray  20  into its position of alignment of ballast  50  with the heat sink corner of housing  40 . This adds to the structural integrity by efficiently distributing the holding forces being exerted on tray  20  and by securing tray  20  at multiple locations. When a short ballast  150  is alternatively used, a ballast extension  151  may be used to provide the ballast fulcrum or, when such extension  151  is not used, tray stop  99  acts to limit the above-described deformation of tray  20  and over-tightening by fastener  60 . However, the full benefit of the fastening structure vis-a-vis ballast tray  20 , where such ballast acts as a spring member in the self-adjustment of tray  20 , is achieved when a ballast of ballast tray  20  is in abutment with top heat sink pad  42 . It is noted that during tightening, angle B acts to direct force vectors at rod  31 , at heat sink pad  42 , and at heat sink pad  43 . 
   Front and rear rod mounting brackets  47 ,  48  are attached to side wall  41  and fastener  60  is attached to side wall  44 . It is understood that the term “side wall” as used herein can refer to portions of housing  40  other than those portions literally on the sides and may refer to portions that are not opposed to one another. For example, posts such as rear and front posts  45 ,  46  are considered parts of adjacent wall  41 , and a given side wall may include curved portions and portions that are angled with respect to top wall  98 . 
     FIG. 10  shows generally the arc of travel of long side  53  of ballast  50 , also shown by the example of  FIGS. 8 and 9 . One end result is placement of long side  53  at a position where a subsequent engagement and fastening of fastening end  28  causes long side  53  to be tightened against rear heat sink  43  with essentially the entire surface area of long side  53  being in contact with rear heat sink  43 . Another end result is placement of top side  52  of ballast  50  at a position where the subsequent tightening of fastener  60  also causes essentially the entire surface area of top side  52  to contact upper heat sink pad  42 . As shown in  FIG. 11 , the tightening of fastener  60  acts to snug ballast  50  into the heat sink corner by forcing sides  52 ,  53  against respective heat sink pads  42 ,  43 . In addition, it is noted that the structures of hook  21 , fastener  60 , and notch  26  each allow for some “slop” due to a loose fit at each of these tray attachment locations, whereby the natural tendency of sides  52 ,  53  to seat themselves against respective heat sink walls  42 ,  43  causes each of such attachment structures to adjust slightly during the placement stage of  FIG. 10  and the fastening stage of  FIG. 11 . Accordingly, a highly efficient heat transfer is effected by the snug, tight abutment of sides  52 ,  53  with respective heat sink pads  42 ,  43 . For example, fastener  60  has a base portion  69  where shaft  61  is loosely attached to housing  40  by a bracket  68 . Shaft  61  preferably has an angled portion (not shown) between bracket  68  and housing  40 , which keeps shaft  61  from falling out and which becomes pressed against an underside of bracket  68  when shaft  61  is engaged with notch  26  and knob  63  is tightened onto shaft  61 . Such a tension type securement of fastener  60  into a tightened position also facilitates the self-adjusting action of the tray attachments due to their loose fit, which increases the ballast placement accuracy and efficiency in snugly seating ballast  50 . 
   When servicing of the lighting fixture  10  becomes necessary, a service person may first turn off the corresponding circuit breaker and remove an outer lens cover (not shown) from the fixture, thereby exposing the inside portion. The service person may then remove any lamp(s) requiring replacement or just leave them in if they are still good and are not likely to be damaged by accessing ballast tray  20 . Then, knob  63  may be turned counter-clockwise to loosen fastener  60  and reduce the force being exerted on tray  20  by fastening surface  62 . When knob  63  has been adequately backed out, the service person may then carefully lift up slightly on fastening end  28  of tray  20  to relieve the force of gravity being exerted onto fastening surface  62 . Such allows fastener  60  to be disengaged from notch  26  and moved near the adjacent side wall of housing  40 , out of the way of ballast tray  20 , which then can be lowered to hang from rod  31  for servicing as shown in  FIG. 6C . A handle (not shown) may be attached to ballast tray  20  for assisting in opening and closing ballast tray  20  and for lifting ballast tray  20  up and over rod  31  when removing or attaching ballast tray  20  to rod  31 . It is noted that fixture  10  may be serviced without any tools being required. For example, a cover plate (not shown) is typically used for attaching a glass or similar lens type structure to housing  40  so that light may be transmitted therethrough. Such cover plate may be provided with fasteners that require no tools. Similarly, knob  63  of fastener  60  is preferably easily gripped and rotated by hand, and is formed of a non-conductive material to reduce the possibility of electric shock to the service person. Component tray  20  may be provided with wire connectors, so that component tray  20  may be loosened using knob  63 , lowered, disconnected from wires of fixture  10 , un-hinged, and then removed from fixture  10 , all without the use of any tools. This provides additional safety in an industrial type ballast installation. 
   The exemplary housing  40  has mounting holes  91  at a rear portion, for optional mounting of light fixture  10  to a post, wall, or other supporting structure. A feed-thru hole  92  is provided for allowing electrical service connections to ballast tray  20  and to one or more lamp sockets. For example, an electrical cord may be secured at feed-thru  92  using a strain relief, grommet, or the like, or a conduit fitting or other suitable structure may be attached for safely providing electrical service. A connection compartment  95  is provided between the curved rear walls  93 ,  94  of housing  40  and the rear side of rear heat sink pad  43 . Such connection compartment  95  provides a convenient space for connecting, for example, individual jumper assemblies (not shown) using twist-on wire connectors and the like, and for installation of an earth ground connection to housing  40 , and for other electrical connections. 
     FIG. 12  shows a housing  40  formed by casting or similar process, although other processes such as welding may be used. A rod mounting bracket base  96  is formed as a portion of a cast housing  40 , bracket base  96  having grooves for receiving rod  31  and having tapped holes for receiving mounting hardware for holding rod  31  in its intended location. In a preferred embodiment, bracket brace  96  has an upper portion having a same height at each end thereof, where one or more rod holders may be attached such as by being secured to threaded receptacles in bracket  96 . Such a bracket  96  has a rod-holding portion with an angle Z formed therein for holding rod  31  at the required angle with respect to heat sink pad  43 . A fastener bracket base  97  has a groove for receiving a hooked bottom portion of fastener  60  and has a tapped hole for receiving mounting hardware for attaching fastener  60  so that it does not fall out of housing  40 . 
   Heat sink pads  42 ,  43  are preferably arranged perpendicularly with respect to one another. As shown in  FIGS. 8 and 9 , top heat sink pad  42  is a separate surface from well portion  49  of housing  40  because the well portion  49  curves away from the flat surface of top heat sink pad  42 . Rear heat sink pad  43 , as shown in  FIG. 1 , is formed as a separate surface that is, for example, joined to housing  40  by welding or other structure. Housing  40  is a heat sink and heat from ballast  50  is transferred to the two respective engaged walls of integral heat sink pads  42 ,  43 . 
   The heat generated in a lighting fixture typically causes components to have a shortened life. A general rule of thumb is that, for every ten degrees Celsius you remove from the lighting fixture, you double the life of individual components. The mounting of a ballast within the enclosure of a lighting fixture housing, for dissipating the generated heat by conduction and radiation, is therefore important to its operation. As a result of implementing the double heat-sinking structure of fixture  10 , as much as ten to fifteen degrees Celsius may be removed. Otherwise, ballast heat would be trapped and damage would result. 
   In conventional structures, heat transfer, from the ballast to the fixture housing which encloses the ballast, lamp and other electrical lighting fixtures, is facilitated by the application of grease, gel, resin and the like to a single surface of the ballast case connected with respect to the housing. Mounting plates have also been used to provide a medium for heat transfer from one surface of the ballast to one surface of the housing. While heat transfer is a major concern in housing design, the housing must also provide free access to ballast components and wiring so that maintenance can be performed. Such an advantage is provided by implementation of the present invention. In addition, the present invention may be applied to situations where a large heat dissipation is not required, but where serviceability and at least some heat reduction is desired, such as for heat sinking protection of heat-sensitive components of a component tray. For example, when a scale is small, a space savings may result from being able to package components in a smaller footprint because heat is conducted to an adjacent housing rather than being accumulated at the heat generation location. 
   Although the illustrated exemplary embodiments each include a ballast tray  20  being disposed in the same housing as a lamp, it is also possible to enclose lamps and ballasts in separate housings. In such a case, it is desirable to install a lighting fixture in close proximity to a ballast housing, so that high voltage wiring between the two structures is minimized. Such a ballast housing (not shown) is preferably provided with a pair of heat sink pads disposed orthogonally with respect to one another, so that a ballast of the housing may be snugly engaged with the corresponding heat sink corner by attachment of ballast tray  20 , as for the embodiment of  FIG. 1  and others described herein. The same serviceability is thereby provided while optimizing heat sinking of the ballast. Similarly, the invention may be implemented in electrical fixtures used in applications other than lighting. For example, a component tray may be attached with a quickly-detachable mechanism for use in any application where a transformer of the component tray becomes hot and it is desired to transfer the heat by conduction to the walls of a housing or other heat sinking structure. 
   While the principles of the invention have been shown and described in connection with specific embodiments, it is to be understood that such embodiments are by way of example and are not limiting. Consequently, variations and modifications commensurate with the above teachings, and with the skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described herein are intended to illustrate best modes known of practicing the invention and to enable others skilled in the art to utilize the invention in such, or other embodiments and with various modifications required by the particular application(s) or use(s) of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.