Patent Publication Number: US-9897294-B2

Title: Commercial lighting integrated platform

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 13/689,489, filed Nov. 29, 2012, and entitled “Commercial Lighting Integrated Platform,” now U.S. patent, which claims the benefit of and priority to U.S. Provisional Application Ser. No. 61/637,115, filed Apr. 23, 2012, entitled “Suspendable LED Light Fixture,” the contents of each of which applications is hereby incorporated herein by reference herein in their entireties. 
    
    
     FIELD OF THE DISCLOSURE 
     The subject disclosure relates to LED light fixtures and more particularly to such fixtures which are modular so that they may vary in length and are readily adaptable to be suspended from or otherwise connected to, a ceiling or a variety of other surfaces in a number of different manners and configurations. 
     RELATED ART 
     In the past, twin tube fluorescent T-5, T-8, and T-12 fixtures have been used to provide overhead illumination. 
     SUMMARY 
     Light fixture apparatus according to one illustrative embodiment comprises one or more interconnectable modules each module comprising a housing mounting an LED circuit board on an underside thereof and having a guide track mounted on a top surface thereof and attached thereto. A slip fitter component is shaped to slidably insert into and engage or attach to the guide track. The apparatus may include a ceiling mounting bracket, a hanger bracket, an eye hanger and/or a cable hanging arrangement, each of which is adapted to mate and interconnect with the slip fitter component to provide multiple modes of hanging or suspending of the one or more lighting modules. 
     A particularly advantageous lighting apparatus embodiment disclosed hereafter may comprise a lighting platform for mounting one or more LEDs having a first bottom cover having respective first and second side channels formed at opposite corners thereof, each side channel comprising a horizontal bottom edge curving into a vertical side edge, and an upper housing having respective outer side surfaces which, at respective upper ends thereof, extend outwardly, then vertically downward, then horizontally inward and then downward to form respective extended end tip surfaces. In one embodiment, respective screws may be inserted through the first and second channels and angled upwardly and threaded into the end tip surfaces of the upper housing to thereby attach the bottom cover to the upper housing. Another advantageous feature comprises a driver assembly for powering the LEDs mounted in an internal cavity defined by the bottom cover and the upper housing, the driver assembly being spring biased upwardly and otherwise configured to facilitate heat transfer between the driver assembly and the upper housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative embodiment of a suspendable LED light fixture apparatus; 
         FIG. 2  is an exploded perspective view illustrating apparatus of  FIG. 1 ; 
         FIG. 3  is a bottom view of a lower housing component of the apparatus of  FIG. 1 ; 
         FIG. 4  is a perspective top view of the housing component of  FIG. 3  and a cooperating printed circuit board; 
         FIG. 5  is a perspective view looking upward at the light fixture apparatus of  FIG. 1 ; 
         FIG. 6  is a sectional view taken at VI-VI of  FIG. 5 ; 
         FIG. 7  is a perspective view of an illustrative ceiling mounting bracket component; 
         FIG. 8  is a side view of the component of  FIG. 7 ; 
         FIG. 9  is a bottom view of the component of  FIG. 8 ; 
         FIG. 10  is a sectional view of the component of  FIG. 7  taken at X-X of  FIG. 7 ; 
         FIG. 11  is a perspective view of an illustrative embodiment of a slip fitter component; 
         FIG. 12  is a cross-sectional view showing an illustrative embodiment of a hanging bracket component; 
         FIG. 13  is a cross-sectional view showing an illustrative embodiment of an eye hanger component; 
         FIG. 14  is a cross-sectional view showing an illustrative embodiment of cable connector apparatus; 
         FIG. 15  is a cross-sectional view further illustrating an embodiment of lighting apparatus suspended by a cable connector; 
         FIG. 16  is a perspective view of an illustrative embodiment of a side panel component of the apparatus of  FIG. 1 ; 
         FIG. 17  is a perspective view of an illustrative embodiment of a first end junction box component; 
         FIG. 18  is a perspective view of an illustrative embodiment of a second end junction box component; 
         FIG. 19  is an end view of the junction box component of  FIG. 18 ; 
         FIG. 20  is a view illustrating a junction box component in an assembled lighting apparatus embodiment; 
         FIGS. 21-23  are perspective views useful in illustrating an illustrative manner of assembly of apparatus according to an illustrative embodiment; 
         FIG. 24  is a schematic perspective view of a multiple module suspended LED light fixture embodiment employing three slip fitter components; 
         FIG. 25  is an exploded perspective view of a second illustrative embodiment; 
         FIG. 26  is a perspective view of the embodiment of  FIG. 25  in an assembled state; 
         FIG. 27  is a side perspective view of the second embodiment with an upper housing component removed; 
         FIG. 28  is a downwardly looking perspective view of the assembly of  FIG. 27 ; 
         FIG. 29  is a cross-sectional view taken at V-V of  FIG. 26 ; 
         FIG. 30  is a side perspective view of a bottom cover component of the second illustrative embodiment; 
         FIG. 31  is a top view of the component of  FIG. 30 ; 
         FIG. 32  is a cross-sectional view taken at VIII-VIII of  FIG. 31 ; 
         FIG. 33  is a perspective view of a cover splice component of the second illustrative embodiment; 
         FIG. 34  is a top view of the component of  FIG. 33 ; 
         FIG. 35  is a bottom view of the component of  FIG. 33 ; 
         FIG. 36  is a perspective view of an end assembly of the second illustrative embodiment; 
         FIG. 37  is a perspective view of a side clip component of the second illustrative embodiment; 
         FIG. 38  is an end view of the component of  FIG. 37 ; 
         FIG. 39  is a partial perspective view illustrating assembly of the end assembly of  FIG. 36 ; 
         FIG. 40  is a first perspective view of an end cover component of the second illustrative embodiment; 
         FIG. 41  is a second perspective view of the end cover component; 
         FIG. 42  is a perspective view of a central slip fitter assembly according to the second illustrative embodiment; 
         FIG. 43  is a schematic perspective view of one embodiment of wire management clip and associated cable suspension assembly; 
         FIGS. 44-46  are end views illustrating various lens attachment mechanisms according to illustrative embodiments; 
         FIG. 47  is an end perspective view of the second illustrative embodiment useful in illustrating the manner of assembly of additional light fixture units or modules according to the second illustrative embodiment; and 
         FIG. 48  is a perspective view illustrating first and second light fixture units or modules assembled together according to an illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     An illustrative embodiment of a suspendable LED light fixture  11  is illustrated in  FIGS. 1-6 . As shown, the illustrative fixture  11  includes a guide track  13 ; first and second lower housing components  15 ,  17 ; respective end mounted junction boxes  19 ,  21 ; central side panels  23 ,  25 ; an LED driver module  27 ; a number of bolts  29 ; and first and second lens covers  32 ,  34  ( FIG. 5 ). The particular apparatus illustrated in  FIG. 1  further includes a slip fitter component  31 , a ceiling bracket mounting component  33  and a jack chain mounting component  35 . The lower housing components  15 ,  17  further comprise suitable vertical heat sink fins, e.g.,  115 , for thermal management purposes and may be fabricated of the zinc alloy Zamak III. The lower housing components, e.g.  15 , are positioned below the guide track  13  with respective outer side faces  16 ,  18  being flushly mounted against the inner edge of respective lips  61 ,  63  ( FIG. 6 ) of the mounting or guide track  13 . 
     One of the lower housing components  15 ,  17  is illustrated in more detail in  FIGS. 3 and 4 . In one embodiment, each lower housing component, e.g.,  15 , is a single piece component and is identical to each other lower housing component. As seen in  FIG. 4 , the lower housing component  15  has a flat, generally rectangular recessed area  215  into which an LED-carrying printed circuit board, e.g.,  53 , may be mounted, for example, by heat conductive double-sided tape. At each end of the recessed area  215  is formed a rounded nose portion  219 ,  221 , each of which has a respective rear edge  220 ,  222 , which rises above the recessed area  215  and provides a surface which positions a respective end of the circuit board  215 . Each rounded nose  219 ,  221  also has a slot  223 ,  225  formed therein, which receives respective prongs  57 ,  59  ( FIG. 6 ) of a lens cover e.g.,  32 . An opening  230  is formed in the recessed area  215  to receive electrical interconnection componentry. 
     As may be seen in  FIG. 3 , the interior of each lower housing component, e.g.,  15 , comprises a generally hollow space, defined by the inside surfaces of respective vertical, generally rectangular sidewalls  241 ,  242 . The outer surfaces of each sidewall  241 ,  242  carry integrally formed vertical heat sink fins, e.g.,  115 . Each rectangular side surface  241 ,  242  forms into a bend  245  at its respective ends and then into a solid rectangular end side surfaces  246 , which in one embodiment may lie generally planar with the outer edges of the vertical heat sink fins  115 . Respective screw or fastener receiving holes, e.g.,  248 , are also provided. 
     As may be appreciated from  FIG. 1  and  FIG. 6 , the slip fitter component  31  is slidingly inserted into, guided and retained by respective horizontally disposed channels  41 ,  43  of u-shaped cross-section formed at opposite sides of the guide track  13 . Screws or other fastening devices  36 ,  38  ( FIG. 2 ) may be inserted through bosses  28 ,  30  into the guide track  13  to fix the slip fitter  31  in position. 
       FIG. 6  further illustrates respective lips  61 ,  63  on either side of the guide track  13 , which fit down flushly adjacent the outer surface of each respective side panel side  311 . The bolts  29  insert through suitable holes and are screwed into respective vertical channels  65 ,  67  of generally rectangular cross-section formed in the guide track  13  below the horizontal channels  41 ,  43 . In the embodiment shown, these vertical channels  65 ,  67  are suitably formed during an extrusion process so that bolts, screws or other fastening devices  29  are self-threading into the channels, thereby avoiding the need to cut threads in the channels  65 ,  67 . Lower vertical channels  45 ,  47  of rectangular cross-section are formed in the side panels  23 ,  25 . The respective inner vertical sides  315  of these channels form unitarily into respective planar horizontal surfaces  52 , which may serve to support the LED driver module  27 .  FIG. 6  further shows one or more LED lighting devices, e.g.,  55  and the lens cover, e.g.,  32  with respective prongs  57 ,  59  positioned, shaped and dimensioned to snap or otherwise fit through suitable apertures  223 ,  225  formed in an end tab or tongue, e.g.,  221  of lower housing component  15 . 
     The embodiment shown in  FIG. 6  particularly employs the ceiling mounting bracket  33 , shown in more detail in  FIGS. 7-10 . As may be seen, the mounting bracket  33  has a central rectangular portion  91  with raised flanges  93 ,  95  having respective holes  94 ,  96  formed at respective ends thereof. A cylindrical portion  97  depends from the underside  98  of the mounting bracket  33 . A cylindrical well  101  is formed in the top portion of the cylindrical portion  97 , and a rectangular bar  103  is formed on the lower end of the cylindrical portion  97 . 
     As may be seen in  FIG. 11 , the slip fitter component  31  has a central slot  105  formed therein, which includes a circular central portion  106  with respectively longitudinally running rectangular end slot portions  107 ,  109 . This central slot  105  is shaped and dimensioned or “keyed” such that the rectangular bar  103  of the ceiling mounting bracket  33  may be inserted therein and then rotated 90 degrees to lock, hold, and retain the ceiling mounting bracket  33  in the position illustrated in  FIG. 6  wherein screws or other fastening devices may be inserted through the respective mounting holes  94 ,  96  to attach the fixture  11  to a ceiling or other surface. 
       FIG. 12  illustrates a hanging bracket  121  employed in an illustrative embodiment. The hanging bracket  121  has a lower end  122  which may be constructed in similar fashion to the ceiling bracket  33  with a horizontal bar keyed to interlock with the central slot  105  of the slip fitter component  31 . The illustrative hanging bracket embodiment  121  includes two vertical extending arms  123 ,  125 , which form into horizontally disposed mounting pads or flanges  127 ,  129 , with suitable mounting holes  131 ,  133  to facilitate attachment to a surface located above the fixture  11 , such as a ceiling or a large soffit in a retrofit construction. 
       FIG. 13  illustrates employment of an eye hanger component  141  according to an illustrative embodiment, which enables the illustrative fixture  11  to be suspended using jack chain or other types of chains or other suspension components which can interconnect with the eye  143  of the hanger component  141 . The eye component  141  is inserted from the underside of the slip fitter component  31  through the central opening  105  thereof during assembly and includes a lower cylindrical flange portion  145 , which retains the eye hanger  141  in place. 
       FIG. 14  illustrates application of an illustrative embodiment adapted to be suspended by a cable  161 . This application employs a cable group connector  163 , whose lower end may be shaped similarly to that of the eye hanger  141  so as to be insertable into the central opening  105  of the slip fitter component  31  through the underside thereof and be retained in place by an end flange portion  165 . The cable gripper connector  163  receives a cable gripper  167  in a central cylindrical opening  164  in its upper end. The cable  161  exits through a side opening in the connector  163  and terminates at end  166 .  FIG. 15  illustrates a cable gripper assembly  163  cooperating with a ceiling mounting assembly  169 . In various embodiments, more than one slip fitter  31  may be inserted into a guide track  13 , for example, as shown in  FIG. 22 , to accommodate various suspension requirements or designs. 
     As shown in  FIG. 16 , a single piece side panel, e.g.,  23 , includes a flat vertical side surface  311  which unitarily forms into a rectangular horizontal surface  313  and then into a vertically depending surface  315 . A horizontal lip  317  is unitarily formed at the end of depending surface  315 . This lip  317  is positioned such that it is located adjacent to, or in contact with, the bottom surface of the driver unit  27 . Vertical side ribs  319 ,  321  provide strength to the unit  23  and are positioned such that a mounting screw, e.g.,  29 , inserted through opening or hole  327  lies between them in a slot  323  defined by the ribs  319 ,  321 . In order to add a third module providing a third housing component, a second pair of panels  23 ,  25  may be used to attach the third module to the one of the first and second modules shown in  FIG. 1 . 
     An end junction box component  19  is illustrated in  FIG. 17 . The component  19  includes respective side surfaces  331 ,  333 , and top surfaces  335 ,  337 , which are flat and positioned to mate and form generally flush surfaces with respective side surfaces and top surfaces of the housing components e.g.,  15 . A channel  339  is formed between the respective top surfaces  335 ,  337  to receive an end tab or tongue, e.g.  22  of the lower housing component  17 . A grounding tab  341  extends from a flat surface  343 . A “knock out”  345  is provided for electrical cable/lead exit or entry. 
       FIG. 18  illustrates a second end junction box component  21 , which is constructed in the same manner as component  19  of  FIG. 15  with the exception that its length “L” is longer to accommodate a longer housing end tongue or tab  20 ,  FIG. 2 . As seen in  FIG. 19 , the component  21  has first and second corner channels  261 ,  262  with respective horizontal surfaces  263 ,  264  meeting at right angles with respective vertical walls  265 ,  266 . As seen in  FIG. 20 , the vertical walls  265 ,  266  of the respective corner channels  261 ,  262  mate with respective inside rails  268 ,  269  of the guide track  13 , while the horizontal surfaces  263 ,  264  rest on the horizontal surfaces of respective outer tracks  271 ,  272  and within the vertical side rails of those outer tracks  271 ,  272 . 
     As illustrated in  FIGS. 21-23 , in assembling one illustrative embodiment, the lower housing components  15 ,  17 , guide tracks  201 ,  202  side panels  23 ,  25 , circuit cards e.g.  53 , and lenses  32 ,  34  may be first respectively assembled together to form two separate modules  205 ,  207 , with the driver component  27  attached in place using thermal tape applied between the driver component and the underside of the guide track, e.g.  201 . In this assembly step, guide tracks  201 ,  202  are placed down onto the upper edges of the sides of the lower housing components  15 ,  17  such that respective lips  61 ,  63  on either side of the guide tracks  201 ,  202  fit down flushly on each respective lower housing side outer surface. The bolts  29  are then inserted through suitable holes and screwed into respective vertical channels  65 ,  67  of generally rectangular cross-section formed in the guide tracks  201 ,  202  below the horizontal channels  41 ,  43 . In the embodiment shown, these vertical channels  65 ,  67  are suitably formed during the extrusion process so that bolts, screws or other fastening devices  29  are self-threading into the channels  65 ,  67 , thereby avoiding the need to cut threads in the channels  65 ,  67 . The slip fitter  31  may then be inserted into the respective guide tracks  201 ,  202  and fastened into place. Thereafter, the side panels  23 ,  25  and junction boxes  19 ,  21  are attached using suitable bolts  29 . While the embodiment of  FIG. 21  illustrates two guide tracks  201 ,  202 , these guide tracks  201 ,  202  may be combined into a single piece component as illustrated in other figures. 
     Illustrative embodiments can produce high levels of light for both general ambient and accent light. Typical applications may include retail, manufacturing and warehouse facilities. Illustrative embodiments may comprise 1 foot, 4 foot, 6 foot, or 8 foot joined together modules, and may have, for example, either 4 or 6 LEDs per foot, producing 600 to over 1000 lumens per foot. A lightly frosted acrylic lens, e.g.,  32 , may be provided in certain embodiments. In illustrative embodiments, the LEDs may be 350 milliamps (ma) or 550 ma units. Certain embodiments permit long runs from a single power feed for ease of installation—120 feet @ 120 volts or 250 feet @ 277 volts power feeds are possible at virtually any point along a run. Electronic Low Voltage (ELV) dimming may be provided in some embodiments such that no additional control wires are necessary. 
       FIG. 25  illustrates an exploded view of a second embodiment of a lighting platform  411 , which includes first and second bottom covers  417 , which attach to an upper housing  419 . In one embodiment, each of these components  417 ,  419  may be fabricated of aluminum. In one illustrative embodiment, the bottom cover components  417  comprise two identical die cast clear anodized aluminum sections, while the upper housing  419  is a single piece aluminum extrusion, fabricated, for example, of 6063-T6 material with a clear anodized finish. Each bottom cover  417  includes first and second side channels  527 , 529 . 
     A semicircular lens components  421  snaps in or otherwise attaches to each bottom cover  417 . In the illustrative embodiments, side tabs  418  formed on the lens component  421  snap into corresponding apertures  420  ( FIG. 30 ) formed in the bottom cover  417 . The lens components  421  surround respective circuit boards  423  carrying one or more LEDs  424  ( FIG. 29 ). 
       FIG. 25  further illustrates a driver unit  425  for powering the LEDs  424  and a driver mounting bracket  427 , which are housed within the platform  11 . The platform  11  further includes an end assembly  426  comprising an end slip fitter  428 , respective right and left side clips  430 , an end cover  432  and a central assembly  434  comprising a slip fitter  436  and respective right and left side clips  430 . Other componentry shown in  FIG. 25  includes wire management clips  438 , edge clips  469 , aircraft cable segments  440 , stake eyes  442 , Philips head screws  435  employed to fasten the bottom covers  417  to the upper housing  419 , springs  429 ,  431 , a splice clip  433 , and double-sided thermal tape  444 . 
       FIG. 26  illustrates the apparatus of  FIG. 25  in an assembled state. As can be seen, the central slip fitter  436  and end slip fitter  428  slide into side rails or channels  446 ,  448  formed on opposite sides of an upper surface  450  of the upper housing  411  and are retained in position by an upper lip  452 ,  454  of each side rail or channel  446 ,  448 . The generally U-shaped edge clips  469  may be fabricated of spring steel and clip down over the ends of adjacent bottom covers  417  to cover the line of joinder of the units  417  and also indicate to a technician servicing the units that there are two components joined together at that point. Their primary function is thus to serve as a visual identifier for service personnel. Also visible in the view of  FIG. 2  are a ground tab  490 , and two bosses  503 ,  505 . 
       FIGS. 27 and 28  illustrate the platform  411  with the upper housing  419  removed. As may be seen, the driver unit  425  for powering the LEDs  424  is positioned in a first of the bottom covers  417  and held in place by a driver bracket  427 , which, in one embodiment, may be formed as a single piece die cast aluminum component. The driver bracket  427  is spring loaded by respective springs  429 ,  431 , as will be described in greater detail below.  FIG. 4  additionally illustrates the cover splice component  433 , which is employed to attach together the adjacent bottom covers  417  via screws inserted through respective holes  517 ,  519  in the splice component  433  and threaded into each of the respective bottom cover sections  417 .  FIG. 28  further illustrates an electrical connector  511  which provides a power feed to a circuit board  423  and a boss  506 . 
     As shown in  FIG. 29 , respective self threading screws  435  are angled and screwed into the upper housing extrusion  419  in order to fasten each bottom cover  417  to the upper housing extrusion  419  in manner which provides contact between the components  417 ,  419  which is tight enough to facilitate optimum heat transfer between the components  417 ,  419  for thermal management purposes. 
     In one embodiment, extended tips or “wings”  437  are provided on depending surfaces  439  of the upper extrusion  419 . These tips  437  and surfaces  439  extend beneath the screws  435  and are shaped and dimensioned such that, if the bottom cover  417  is properly mated and aligned with the upper extrusion  419 , the screws  435  will bite in and pull the units  417 ,  419  more tightly together, whereas, if they are misaligned the screws  435  will not bite and hold at all. 
     As further shown in  FIG. 29 , in the interior of the lighting platform  411 , a wire management clip  438  fits between respective vertical edges  443 ,  445  of the upper housing  419  and assists in defining a wire way  447  between the clip  438  and the outer right side  449  of the upper extrusion  419 . In one embodiment, illustrated in  FIG. 43 , a loop of an aircraft cable segment  440  may be wrapped around respective fingers of the clip  438  and a screw  504  inserted through a stake eye  442  and into a boss  505  formed unitarily with the bottom cover  417 . In another embodiment, a cable may be attached to the lower edge of a similar clip by a screw and similarly attached to a boss integrally formed with the bottom cover  417 . In this manner, if the screws  435  are removed, e.g., for maintenance purposes, the bottom cover  417  will be suspended by the cable, rather than falling to the floor. In one embodiment, the clip  438  may be a rigid PVC material, but could be fabricated of different material in different embodiments. 
       FIGS. 27-29  further illustrate apparatus which forces the driver unit  425  upwardly to create firm contact with an upper horizontal surface  453  of the upper housing  419 , to further facilitate heat transfer for thermal management purposes. In the illustrative embodiment, this apparatus includes the driver bracket  427  to which the driver  425  is attached and the first and second springs  429 ,  431  which are mounted on the interior floor of the casting  417 , for example, around interior posts (not seen). The driver bracket  427  has suitable unitarily formed vertical flanges  455 ,  457  and bolts  459 ,  461 , which extend through the flanges  455 ,  457  and attach bosses  503 ,  506  unitarily formed as part of the bottom cover  417 . 
     In one embodiment, the top surface  464  of the driver unit  425  is attached to an undersurface  465  of the driver bracket  427  by double sided thermal adhesive tape. The springs  429 ,  431  are put in compression mode when the bottom cover  417  and upper housing  419  are attached together, thereby pressing the top surface  463  of driver bracket  425  against the horizontal surface  453  of the upper housing  419 . In one embodiment, the driver unit housing itself could have flanges formed integrally or unitarily therewith or thereon to accommodate the bolts  459 ,  461 , thereby eliminating the need for a driver bracket such as bracket  427 . 
       FIG. 29  further illustrates that the upper housing extrusion  419  has respective sidewardly facing oppositely disposed inner u-shaped channels  446 ,  448  suitably formed at the top thereof to receive respective wings  556 ,  558  of the slip fitter components, e.g.,  436 . The slip fitter components  436 ,  428 , may accommodate various suspension or hanging mechanisms, for example, such as those shown in  FIGS. 1, 2, 6-15 and 24 . For example, a jack chain mounting component similar to component  35  may be threaded into openings such as a threaded opening, e.g.  588 , of the slip fitter components  428 ,  436 . Keyed mounting or suspension brackets similar to bracket  33  can be attached using slots such as  535 ,  537  in the slip fitters  428 ,  436 . In one embodiment, the slip fitters  428 ,  436  may be fabricated of die cast aluminum. 
       FIGS. 30-32  further illustrate the bottom cover extrusion  417  and bosses  503 ,  505 ,  506  integrally formed therewith. Each side of the bottom cover  417  has respective circular holes  525  and screw holes  526  formed therein. 
       FIGS. 33-35  illustrate the cover splice component  433 , which, in one embodiment, may be fabricated of die cast aluminum. As shown, the splice component  433  is provided with screw holes  517 ,  519  and cylindrical holes  521 ,  523 , through which boss  503  may pass to receive a bolt  429 . Slots  525 ,  527  accommodate the contour of the bottom cover  417  to which splice component  433  is attached. 
       FIGS. 36-41  further illustrate the end assembly  426  of the illustrative embodiment. As may be seen, the left and right side clips  430  slidably mate with the end cover  432 . In particular, the upper vertical edge surface  462  and downwardly angled lower surface  464  ( FIG. 38 ) beneath slide into and mate with a conforming vertical side surface or edge  466  and downwardly angled lower surface  468  ( FIG. 40 ) of the end cover  432 . The generally flat horizontal and vertical back surfaces  470 ,  476  ( FIG. 38 ) of each side clip  430  abut respective horizontal and vertical edge surfaces  472 ,  484 , formed on the end cover  432  and are shaped and dimensioned to flushly mate with those surfaces  472 . The back surface  470  is formed on a flange  478  ( FIG. 37 ), which extends horizontally and inwardly. Finally, as shown in  FIG. 36 , a lower horizontal interior side edge  486  on each side of the clip  430  abuts, touches or engages an interior vertical lip  488  formed on each side of the end cover  432 . 
     As shown, for example, in  FIG. 37 , the inwardly projecting horizontal flange  478  of the side clip  430  has three holes  479 ,  580 ,  481  formed therein and a central semicircular cut-out or opening  482 . As illustrated in  FIG. 39 , the side holes  479 ,  481  receive respective plugs  482 ,  484  formed on the underside of the end slip fitter  428 , while the semicircular opening  482  is sized to slidably receive and mate with the circular cylindrical outer surface  486  of the central threaded plug  588  of the end slip fitter. 
     As seen in  FIGS. 36 and 39 , the circular plug  588  of the slip fitter  428  has a vertically depending tab  590  formed thereon, which includes a hole  591  which receives a screw  501  which threads into a horizontally extending boss  493  formed as part of the end cover  432  to thereby attach the end slip fitter  428  to the end cover  432 . As shown in  FIGS. 39 and 40 , the rear slip fitter  428  includes a rear horizontal lip  494  which is shaped and dimensioned to slide onto and over a mating horizontal lip  496  formed on the end cover  432 . As seen in  FIG. 26 , the lip  494  and mating lip  496  are so shaped and dimensioned that the top surface  498  of the end slip fitter  428  flushly mates with the upper horizontal edge  499  of the end cover  432 . 
     The central holes  580  formed in the horizontal flange of the clips  430  permit screws to be inserted into respective holes, e.g.,  500 , in the underside of the end slip fitter  428  to thereby attach the clips  430  to the end slip fitter  428 . In assembly, in one embodiment, the clips  430  are first attached to the end slip fitter  428  using screws, and the slip fitter and clips subassembly is then inserted into the end cover  432  and screwed in place using a screw  501 , as illustrated, for example, in  FIG. 36 . As will be observed, the inner end  502  of the end slip fitter  428  extends beyond the clips  430  and is shaped and dimensioned such that its side projections or wings  456 ,  458  mate with the guide track or channels  446 ,  448  formed on the upper housing, in the same fashion as the central slip fitter  434 . 
     With respect to in  FIG. 42 , respective side clips  430  are attached to the central area of the central slip fitter  436  in the same manner as the side clips  430  are attached to the end slip fitter  428 , i.e. employing two pegs and matching holes and a central screw hole, e.g. as shown in  FIG. 39 . The design of the illustrated embodiment thus permits each end clip  430  to have identical structure, which is advantageous in reducing part count and manufacturing cost. 
     As illustrated in  FIGS. 47 and 48 , a second unit  12  comprising an upper housing extrusion  419  and bottom cover(s)  417  may be joined to the first unit  11  depicted in  FIG. 25  using the slip fitter  436  and side clips  430 . As shown, when attached to the first unit  11 , the end of the slip fitter  436  extends beyond the end of the upper extrusion  419  and bottom cover  417  of the first unit  11 , as does a portion of each of the side clips  430 . The second unit  12  may then simply be slid into the slip fitter  436  and side clips  430  and the screws  550  tightened down against the top surfaces  450  to hold the units  11 ,  12  together. The left-most end of the unit  12  may be closed by attaching another end assembly  426 . The side clips  430  function to provide an aesthetically pleasing appearance by covering gaps between the units  11 ,  12  and accommodating any “slop” or slightly off tolerances between the two units  11 ,  12 . More units such as  11 ,  12  may be joined together to form even longer light fixture assemblies such as 4, 6 and 8 foot lengths, which can replace T5, T8, or T12 fluorescent fixtures and various other conventional lamps in various environments such as grocery stores, garages, high end retail and convention centers. In one embodiment, the side clips  430  and end covers  432  may be die cast aluminum parts. 
     It may be noted that, in various embodiments, the upper housing  419  may have one or more built-in lens attachment mechanisms. One of these mechanisms may comprise a pair of downwardly facing u-shaped channels  473 ,  475  at respective upper corners of the extrusion  419 , while another may comprise respective openings  477 ,  479  on each side of the lower end of the upper extrusion  419 . A third mechanism comprises channels  481 ,  483  formed on the bottom surface of the casting  417 .  FIGS. 44-46  illustrate lenses  485 ,  487  (rectangular),  489  (wrap around tube) respectively installed using these mechanisms to create three different types of fixtures. 
     Those skilled in the art will appreciate that various adaptations and modifications of the just described illustrative embodiments can be configured without departing from the scope and spirit of the invention. For example, various materials have been specified above for fabricating illustrative embodiments, and such materials may of course be different in different embodiments. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.