Abstract:
An electric lighting system for concealed lighting and track lighting installations has lamp holders spaced along a custom power cable with two finely braided high current conductors. The cable and conductors have a flattened rectangular cross section and are exceptionally pliable to facilitate cornering in tight spaces. The cable exterior is slotted for reduced height of the installed lamp holders and optimum low profile of concealed lighting installations. The lamp holders are adaptable to different types of lamps and include an optional reflector. Snap-on mounting lugs permit installation of the cable and lamp holders directly to a mounting surface. Alternatively, a low profile track holds the cable and lamp holders.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention pertains to the field of electric lighting and more specifically relates to a modular lighting system suitable for track mounting or trackless installation, for example, as concealed strip lighting in wall sconces and the like. 
     2. Background of the Invention 
     Track lighting and strip lighting is widely used, particularly in commercial settings, and many fixtures and modular systems of that type are available. Nonetheless, improvement is desirable in several aspects of those lighting systems. 
     SUMMARY OF THE INVENTION 
     An electric lighting system is disclosed having a power distribution cable with two braided conductors covered in an electrically insulating jacket and lamp sockets spaced along the cable in electrical contact with the conductors for supplying electrical power to a lamp installed in each socket. The cable has a generally rectangular cable cross section with a cable width greater than the cable thickness. 
     The power cable has braided conductors each of generally rectangular conductor cross section, and the braided conductors are flat rope braided with multiple braids each having multiple strands. In a presently preferred cable each conductor has about seven braids of about twenty four strands each, and each of the two conductors is braided with about 168 strands of 0.005 inch diameter copper. The preferred cable width is approximately 0.6 inches and the cable height approximately 0.1 inches. The conductors have a conductor width of about 0.1350 inches and a conductor height of approximately 0.05 inch, the conductor width being parallel to the cable width and transverse to the cable height. 
     The insulation defines a cable top and a cable bottom and a longitudinal slot of generally rectangular cross section in each of the top and the bottom, such that the cable in cross section also resembles two rectangles with rounded corners joined along adjacent short sides by a narrow bridge. The insulation may be of relatively soft and pliable, self healing polyvinylchloride (PVC). 
     The cable is pliable such that it can be bent or folded tightly to make an L shaped corner bend for following corners while keeping the cable generally flat on either side of the corner. The L shape can be made by twisting the cable from a flat condition on either side of the corner from a flat condition through approximately a forty five degree angle to a make a corner fold. Alternatively an L turn can be made by folding the cable over itself along a diagonal fold line. 
     Each lamp socket has a socket top and a socket bottom adapted to make interlocking engagement with each other for capturing the cable therebetween. The socket top and the socket bottom each have a center ridge or boss shaped to mate into the longitudinal center slot in the cable top and the cable bottom respectively. 
     The socket bottom has two socket sides and the socket top is seated onto the socket bottom between the socket sides and is fastened thereto by interlocking portions integral to the socket top and the socket bottom. Lamp contacts supported on the socket top have piercing prongs projecting beneath the socket top for penetrating the insulating jacket and making electrical contact with the parallel conductors of the captive cable. Each piercing prong preferably penetrates the cable near the center of a corresponding one of the conductors. The lamp contacts are adapted and configured for receiving the opposite end contacts of a festoon type double ended tubular lamp with a lamp axis held between the lamp contacts in generally parallel relation to the power distribution cable. The socket top is molded of thermoplastic material with two integrally formed contact holders for receiving and supporting the lamp contacts. 
     A heat shield is retained to the socket top between the contact holders. The heat shield may be a metal plate retained by top prongs integral with the socket top. A light reflector, such as a parabolic light reflector, may be interchangeable with the heat shield on the socket top. The light reflector may be curved only in a direction transverse to the lamp socket and may be selectively weakened along break-away lines for facilitating separation of either of two reflector wings from a reflector center, the reflector center being retained to the socket top by the top prongs. 
     A mounting lug is adapted to make snap retentive engagement with each lamp socket, with a hole in the lug for passing a fastener such as a wood screw, such that each lamp socket can be secured to a mounting surface, such as a wall or ceiling, by the fastener passing through the hole in a corresponding lug. 
     The lamp contacts on each lamp socket are configured for receiving a festoon type lamp with festoon contacts at opposite ends of a generally cylindrical lamp body. An adapter is provided for installing in the festoon lamp socket an MR type lamp having parallel pin contacts extending from a lamp base. The adapter has a frame having a longitudinal axis and a transverse axis, the frame being supported along its longitudinal axis between a pair of festoon contacts, a lamp holder on the frame, a pair of conductive clip inserts fitted in clip receptacles defined in the lamp holder, pin holes in the lamp holder communicating the clip receptacles to a lamp seat surface on the lamp holder such that lamp pins inserted in the pin holes come into electrical contact with the clip inserts, the clip inserts supporting the lamp holder to the frame for pivotal movement about the transverse axis, and electrical connectors on the frame for interconnecting each clip insert to a corresponding one of the festoon contacts, such that electrical power is provided from the festoon contacts to lamp pins inserted in the pin holes. Preferably, the clip inserts are pivotable about a first pair of conductive rivets supported on the frame, the festoon contacts are fastened to the frame by a second pair of conductive rivets, and the electrical conductors comprise conductive strips between the first rivets and the second rivets. The lamp holder may be generally tubular and the clip receptacles are opposite ends of a bore through the lamp holder. 
     The adapter can be provided with a centrally apertured dished light shield having a rearwardly extending axial collar about its central aperture. A generally U-shaped clip is fitted about the lamp holder and has clip ends in releasable retentive engagement with the collar for attaching the collar to the lamp holder, such that a lamp may be inserted through the collar into the pin holes of the adapter without separating the shield from the lamp holder. The collar may be integrally formed with the dished light shield with diametrically opposed openings stamped out in the collar for admitting the clip ends of the clip into retentive engagement with the collar. 
     An end cap is provided for terminating and supporting an end of the power distribution cable. The end cap has a cap top and a cap bottom assembled to each other in releasable interlocking engagement for capturing therebetween the end of the cable. The cap top and cap bottom each have longitudinal center ridges or bosses configured to mate into the longitudinal center slot in the cable top and the cable bottom respectively. The cap bottom has cap bottom side walls and the cap top is seated on the cap bottom between the cap bottom side walls and is fastened thereto by interlocking portions integral to the cap top and the cap bottom. The interlocking portions may include tabs on the cap top engageable in corresponding tab slots defined in the cap bottom. Preferably, the cap top and the cap bottom each have three side walls and an open side, the three side walls of the cap top are received between the three side walls of the cap bottom in the assembled condition of the end cap with the cable end captive therebetween. A mounting lug is adapted to make snap retentive engagement with the end cap, preferably with the cap bottom, such that the end cap may be fastened to a mounting surface by a fastener passing through a hole in the lug. The mounting lug may have lug prongs engageable in a slot defined in the cap bottom for making snap retentive engagement with the end cap. The same mounting lugs may be used for mounting both the lamp sockets and the end cap. 
     Mounting clips are provided for supporting the power cable to a mounting surface at locations spaced from lamp sockets. The mounting clip has a clip plate with a contact side for placement against a mounting surface, at least one and preferably two clip arms on an opposite side of the clip plate, and a hole for passing a mounting fastener through the plate. A contact adhesive may be provided on the contact side of the plate, for example for holding the mounting clip on the mounting surface while a fastener is installed through the plate. 
     As an alternative to use of mounting lugs or mounting clips to hold the cable and attached sockets to a mounting surface, a track is provided with two track side walls and a track bottom. The track is attached to a mounting surface with track fasteners such as screws passing through holes spaced along the track bottom. The track receives the power cable and interlocks with lamp sockets inserted between the track side walls. A side ridge along each side wall of the track fits into side grooves formed in each lamp socket to make snap retentive engagement for holding the lamp socket in the track. The track may be an extrusion of plastic or other suitable material, and a translucent or transparent lens such as a prismatic lens can be installed over the track as by snap interlock with the sides of the track. 
     In one form of the invention a wire guide is provided on an outer side of each of the track side walls for guiding additional single conductor insulated electrical wires along the sides of the track. The wire guides may be integral with the track, for example, extruded integrally with the track. The wire guides are each shaped for holding captive an electrical wire against a mounting surface underlying the track bottom. 
     These and other features, improvements and advantages of the present invention will be better understood by reference to the following detailed description of the preferred embodiments and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows in perspective view a length of strip lighting according to this invention with the power cable bent to make an L shaped turn; 
         FIG. 1A  shows a typical concealed lighting installation using the strip light of  FIG. 1 ; 
         FIG. 1B  shows a strip lighting section as in  FIG. 1  but with the power cable folded over itself to make an L turn; 
         FIG. 1C  is an enlarged fragmentary view of the bend in the power cable of  FIG. 1 ; 
         FIG. 1D  is an enlarged fragmentary view of the fold in the power cable of  FIG. 1B ; 
         FIG. 2  is a cross section of the power cable of the strip lighting of  FIGS. 1 and 1B ; 
         FIG. 3  is a perspective view of a festoon type lamp socket with assembled mounting lug and screw fastener; 
         FIG. 4  is an exploded view of the lamp socket, mounting lug and screw fastener of  FIG. 3 ; 
         FIG. 5  is an end view of the lamp socket of  FIG. 3  shown installed on the power cable, the latter suggested in phantom lining; 
         FIG. 6  is a perspective view of the festoon type lamp socket with assembled mounting lug and screw fastener of  FIG. 3  shown installed on the power cable; 
         FIG. 7  shows the lamp socket as in  FIG. 3  with a parabolic light reflector in exploded relationship to the socket as a replacement for the heat shield plate in  FIG. 3 ; 
         FIG. 8  is a top plan view of the parabolic light reflector of  FIG. 7  with the two break-away lines suggested in dotted lining; 
         FIG. 8A  is an end view of the parabolic light reflector of  FIG. 7 ; 
         FIG. 8B  is an end view of the parabolic light reflector of  FIG. 7  with one wing of the reflector broken away; 
         FIG. 9  is a view as in  FIG. 7  but showing the parabolic reflector installed on the lamp socket and the lamp socket installed on the power cable; 
         FIG. 10  shows the festoon type lamp socket as in  FIG. 7  and, in exploded relationship, an MR lamp adapter with light shield for the festoon lamp socket; 
         FIG. 11  is a view as in  FIG. 10  showing the MR lamp adapter installed on the festoon type lamp socket; 
         FIG. 12  is an exploded perspective view of the light shield and its retaining clip with the MR lamp adapter; 
         FIG. 13  is a perspective view of the MR lamp adapter of  FIG. 10 ; 
         FIG. 14  is an exploded perspective view of the MR lamp adapter of  FIG. 13 ; 
         FIG. 15  is a perspective view of the cable mounting clip according to this invention: 
         FIG. 16  is a perspective view showing the cable mounting clip of  FIG. 15  holding the power cable; 
         FIG. 17  is a perspective view of the end cap installed for terminating an end of the power cable and assembled to a mounting lug and screw fastener; 
         FIG. 18  is an exploded perspective view of the end cap, mounting lug and screw fastener of  FIG. 17 ; 
         FIG. 19  is a perspective view of a terminal strip block for connecting the power cable to a pair of electrical supply wires; 
         FIG. 20  is a view as in  FIG. 19  showing the cover of the terminal strip block open for access to the terminal strip screws; 
         FIG. 21  is an exploded view of the terminal strip block of  FIG. 19 ; 
         FIG. 22  is a perspective view of a junction box :assembled to an end of the power cable for splicing the power cable to a pair of electrical supply wires; 
         FIG. 23  is an exploded view of the junction box of  FIG. 22 ; 
         FIG. 24  is a perspective view of a junction box assembled to two cable ends for making an L splice between the cable ends; 
         FIG. 25  is an exploded view of the junction box of  FIG. 24 ; 
         FIG. 26  is an exploded cross sectional view of a festoon lamp socket, track section and lens; 
         FIG. 27  Is an assembled perspective view of a track section with assembled lens and housing a length of strip lighting consisting of a power cable with lamp sockets installed on the cable at regular intervals; 
         FIG. 28  is an assembled cross sectional view of the festoon lamp socket, track section and lens of  FIG. 26 ; 
         FIG. 29  is an exploded cross sectional view of a festoon lamp socket, wall wash type track section and lens; 
         FIG. 30  is an assembled perspective view of the wall wash track section with assembled lens and housing a length of strip lighting consisting of a power cable with lamp sockets installed on the cable at regular intervals; 
         FIG. 31  is an assembled cross sectional view of the festoon lamp socket, wall wash track section and lens of  FIG. 29 ; 
         FIG. 32  is an exploded cross sectional view of a festoon lamp socket, chaser type track section and lens; 
         FIG. 33  is an assembled perspective view of the chaser type track section with assembled lens and housing a length of strip lighting consisting of a power cable with lamp sockets installed on the cable at regular intervals, and showing chaser wires along the outer sides of the track; 
         FIG. 34  is an assembled cross sectional view of the festoon lamp socket, chaser type track section with chaser wires and lens of  FIG. 32 ; 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the drawings wherein like elements are designated by like numerals,  FIG. 1  shows a length of strip lighting generally designated by numeral  10  which has an electrical power distribution cable  12  and lamp sockets  14  spaced at regular intervals along cable  12 . 
       FIG. 2  shows a cross section of the power cable  12 , with two parallel electrical conductors  16  covered in electrical insulation  18 . The cable insulation  18  is generally rectangular in cross section with a cable top  18   a,  a cable bottom  18   b  and two cable sides  18   c.  The cable top and cable bottom are planar and parallel to each other and are each divided by a longitudinal center slot  20 . Slots  20  have a generally rectangular cross section with two slot walls  20   a  perpendicular to a slot bottom  20   b.    FIG. 2  shows the presently preferred dimensions of the power cable  20 , with a small cable height of 0.1 inch relative to a greater width of 0.6 inch, yielding a relatively large width to height ratio. The insulation  18  has a minimum thickness of about 0.05 inch as measured between the bottoms  20   b  of the upper and lower slots  20 , a slot depth of 0.025 inch and a slot width of 0.05 inch between slot walls  20   a.  The insulation is made of a relatively soft grade of polyvinylchloride, selected to be self healing when pierced. 
     The conductors  16  are rectangular in cross section. The preferred braiding is a flat rope braid using 0.005 inch diameter copper strands: with seven braids of twenty four strands each, such that each conductor  16  is braided with about 168 strands. The resulting stranded conductor is gauge equivalent to AWG 14. The braided conductors are hammered to the rectangular cross section from an initial round cross section of the rope braiding, and then covered with insulation  18 . The conductors  16  have a conductor width of 0.1350 inch and a conductor height of 0.05 inch, as indicated in  FIG. 2  of the drawings, or a ratio of approximately 2.7 times conductor width to conductor height. From the foregoing it will be evident that the cable also has a ratio of approximately 4.5 times conductor width to cable width, and a ratio of 2 times conductor height to cable height. 
     The resulting power cable  12  is pliable to a substantially greater degree than other power cable of comparable capacity used until now in strip lighting, and particularly more pliable than twin conductor cord having round insulation about each conductor. The power cable  12  can be easily bent to make relatively tight small radius corner turns and folds. 
       FIG. 1  shows cable  12  bent into a right angle turn or L shaped turn, designated by the letter “T”, over a relatively short length of cable  12  between two adjacent lamp sockets  14 . Significantly, the cable  12  under each of the sockets  14  immediately adjacent to the turn T lies flat on an underlying mounting surface. This is important since each socket is fastened to the mounting surface as will be explained below. Also, the short length of cable  12  required for making the turn T is significant because the strip lighting  10  is in part sold in prefabricated lengths of cable with lamp sockets  14  installed on the cable  12  at regular intervals, such as 3 inch, 6 inch and 10 inch spacing between sockets  14 . Since the sockets are all pre-installed on one side of the cable  12 , the same side of the cable must be flat against the common mounting surface on either side of the turn T, and as the available length of cable  12  between the adjacent sockets  14  can be small, the pliability of cable  12  facilitates installation of the strip lighting  10 . In conventional strip lighting using heavy gauge round power cord it is frequently necessary to cut and splice the power cord to make tight turns because the cord cannot be bent or folded to a sufficient degree. 
     In  FIG. 1  the L shaped turn T is made by twisting the cable  12 , from an initially flat condition on an underlying supporting plane P supporting the cable  12  and lamp sockets  14 , through about a 45 degree twist along the cable on each side of the turn so as to form a relatively sharp bend B with an imaginary bend line b-b across the cable  12 , so that the bend line lies at approximately a 45 degree angle to the plane P of the initially flat cable  12 , as best seen in  FIG. 1C . This type of turn or bend T is suitable for the prefabricated strip lighting  10  because all sockets  14  are preinstalled on one side of the cable  12  and the same side of the cable stays up on each side of the turn 
       FIG. 1A  illustrates how the tight turn T of the strip lighting  10  benefits a concealed lighting installation recessed in a narrow cove molding M. 
       FIG. 1B  shows a right angle turn or L shaped fold, designated by the letter “F”, made by folding cable  12  over itself along a diagonal fold line f-f as best seen in  FIG. 1D . This kind of cable fold is useful in cases where the cable  12  and lamp sockets  14  are purchased “loose” by an end user and the fold line f-f can be located along the cable before the lamp sockets  14  are assembled to the cable, so that sockets can be mounted on different upper facing sides of the cable  12  on each side of the fold F. 
       FIGS. 3 and 4  show a lamp socket  14  having a socket top  22  and a socket bottom  24  adapted to make interlocking engagement with each other for capturing the cable  12  therebetween, and lamp contacts  26  supported on the socket top  22  and which terminate in piercing prongs  28  projecting beneath the socket top. The piercing prongs  28  penetrate the cable insulation  18  of the captive cable  12  as best seen in  FIG. 5  and make electrical contact with the parallel conductors  16 , each piercing prong  28  preferably penetrating near the center of a corresponding one of the conductors  16 . The conductors  16  are formed with a width greater than their height, as previously explained, to provide a greater piercing area to the piercing prongs  28 . The socket top  22  and the socket bottom  24  each have a center ridge  40  or boss shaped to mate into the longitudinal center slot  20  in the cable top  18   a  and the cable bottom  18   b,  respectively, to help position the cable  12  in relation to the piercing prongs  28  and ensure electrical contact by the piercing prongs with conductors  16 . The socket bottom  24  has two socket bottom side walls  24   a  and two open ends  24   b.  The socket top  22  has two socket top side walls  22   a  and is seated on the socket bottom  24  between the side walls  24   a.  The socket top is fastened to the socket bottom by interlocking portions  22   c,    24   c  integral to the socket top and the socket bottom, respectively, namely, tabs  22   c  configured to snap into tab openings  24   c.    
     The lamp contacts  26  are adapted and configured for receiving the opposite end contacts Lc of a conventional festoon type double ended lamp L held of tubular configuration with a lamp axis Lx generally parallel to the power distribution cable  20 , as shown in  FIG. 6 . The socket top  22  is molded of thermoplastic material with two integrally formed contact holders  22   b  for receiving and supporting the lamp contacts  26  with contact arms  26   a  projecting upwardly from the socket top and contact base  26   b  captive under the socket top  22  in contact holder  22   b.  A heat shield  30  is retained to the socket top  22  between the contact holders  22   b  under the central light emitting portion of the festoon: lamp L. The central portion of the lamp L typically becomes hottest and shield plate  30  protects the thermoplastic material of socket top  22  against excessive heating by dissipating heat over a larger area. The heat shield  30  may be a metal plate retained by top prongs  32  integral with the socket top  22 . 
     A light reflector, such as a parabolic light reflector  34  seen in  FIGS. 7-8B , may be interchangeable with the heat shield  30  on the socket top. The light reflector  34  is flat in a longitudinal direction and is curved only in a direction transverse to the lamp socket  14 . A series of rectangular holes  34   a  are punched in the reflector to selectively weaken the reflector along imaginary break-away lines  34   b  for facilitating separation of either of two reflector wings  34   d  from a reflector center  34   c,  the reflector center  34   c  being retained to the socket top  22  by the top prongs  32  in a manner analogous to retention of the heat shield plate  30  depicted in  FIG. 3 . Reflector  34  with both wings  34   d  generally directs light from lamp L in a beam away from the reflector center.  FIG. 8B  shows reflector  34  with one reflector wing  34   d  broken away from reflector center  34   c  resulting in more light being directed to one side of lamp L away from the remaining reflector wing  34   d.    
     A mounting lug  42  is adapted to make snap retentive engagement with each lamp socket  14 , as seen in  FIGS. 3 and 4 . Lug  42  is ear shaped with a rounded outer edge  42   a,  a flat inner edge  42   b  and a hole  42   c  through the lug for passing a fastener such as a wood screw S through the hole, such that each lamp socket  14  can be individually fastened to a mounting surface. Each lug  42  holds down a corresponding lamp socket  14  and the lugs collectively also support cable  12  running through the sockets  14 . 
     The lamp contacts  26  on each lamp socket  14  are configured for receiving a festoon type lamp L which is a conventional lamp configuration characterized by a tubular overall shape with cylindrical metal contacts at opposite ends of a generally cylindrical glass body. In order to enable use of lamps other than festoon lamps in the lighting system  10 , an adapter  44  is provided for installing an MR type lamp, also a conventional lamp configuration having parallel pin contacts extending from a lamp base. As seen in  FIGS. 10-14  the adapter  44  has a frame  46  with a longitudinal axis and a transverse axis. Frame  46  is held between the festoon lamp contacts  26  of the lamp socket  14  along its longitudinal axis. Frame  46  supports a lamp holder  48  and a pair of conductive clip inserts  50  fitted in clip receptacles  52  defined in the lamp holder  48 . Two pin holes  52  in the lamp holder  48  are open between and communicate the clip receptacles  52  to a lamp seat surface  54  on the lamp holder  48 , such that lamp pins of an MR type bulb inserted in the pin holes  52  come into electrical contact with one end of the clip inserts  50 . The clip inserts  50  serve as bearings to support the lamp holder  48  to frame  46  for pivotal movement about the transverse axis of the frame, and electrical connectors  56  are provided on the frame  46  for interconnecting each clip insert  50  to a corresponding one of the adapter&#39;s festoon contacts  58 , such that electrical power is provided from the festoon contacts  58  to lamp pins inserted in the pin holes  52 . The clip inserts  50  are pivotable about a first pair of conductive rivets  60   a  supported on the frame  46 , the adapter festoon contacts  58  are fastened to the frame  46  by a second pair of conductive rivets  60   b,  and the electrical conductors  56  are conductive strips in connected by electrical contact between the first rivets  60   a  and the second rivets  60   b.  The lamp holder  48  is generally tubular with a flat lamp seat surface  54 , and the clip receptacles  52  are opposite ends of a bore passing through the lamp holder  48 . 
     The adapter  44  can be provided with a centrally apertured dished light shield  62 , for example, an aluminum spinning with a rearwardly extending axial collar  64  about its central aperture. A generally U-shaped retaining clip  66  fits about lamp holder  48  and has clip ends  66   a  which make releasable retentive engagement with the collar  64  for holding the collar  64  to the lamp holder  48 , such that the base of an MR type lamp may be inserted through the collar  64  onto the lamp seat surface  54  and the lamp pins inserted into pin holes  52  without separating the light shield  62  from the lamp holder  48 . The collar  64  may be integrally formed with the light shield  62  and with diametrically opposed openings  64   a  stamped out in the collar  64  for admitting the clip ends  66   a  into the aforementioned retentive engagement. 
     An end cap  70  shown in  FIGS. 17 and 18  is provided for supporting and terminating an end of the power distribution cable  12 . The end cap  70  has a cap top  72  and a cap bottom  74  assembled to each other in releasable interlocking engagement or snap lock assembly for capturing between them an end of the power distribution cable  12 . The cap top  72  and cap bottom  74  each have a longitudinal center ridge  76  or boss configured to mate into the longitudinal center slot  20  in the cable top  1  Ba and the cable bottom  18   b  respectively. 
     The cap bottom  74  has two cap bottom sides  74   a  and the cap top  76  is seated onto the cap bottom  74  between the cap bottom sides  74   a  and is fastened thereto by interlocking portions integral to the cap top and the cap bottom. The interlocking portions may include tabs  76   b  on the cap top  76  engageable in corresponding tab slots  74   b  defined in the cap bottom  74 . Preferably, the cap top  76  and the cap bottom  74  each have three sides  76   a,    74   a  respectively and an open side  76   d,    74   d,  respectively. The three sides  76   a  of the cap top  76  are received between the three sides  74   a  of the cap bottom  74  in the assembled condition of the end cap  72  shown in  FIG. 17 . The cable  12  enters the end cap  72  through the aligned open sides  76   d,    74   d.  Raised bumps  78  on cap top and bottom press into the resilient insulation  18  of cable  12  and keep the cable end from being easily pulled out of the end cap  72 . 
     A mounting lug  42  identical to the lug  42  used for mounting lamp sockets  14  above is adapted to make snap retentive engagement with the end cap  72  such that the end cap may be secured to a mounting surface by a fastener, such as wood screw S, passing through hole  42   c  in the lug. The lug  42  has two barbed lug prongs  42   d  engageable in a slot  78  defined in the cap bottom  74  for making snap retentive engagement with the assembled end cap  72 . The lug prongs have cam surfaces  42   e  which are squeezed together by side edges  78   a  of the slot  78  when the prongs are pressed into the slot and then spring away from each other inside the cap  72  holding the lug  42  against the side  74   a  of the cap bottom. Engagement of lug  42  to lamp socket  14  is similar by engaging lug  42  In slot  25  provided in socket bottom  24 . 
     One or more mounting clips  80  shown in  FIGS. 15 and 16  may be provided for supporting the power distribution cable  12  to a mounting surface where support may be needed, for example at locations away from lamp sockets  14 . The mounting clip  80  has a clip plate  82  having a contact side  80   a  for placement against a mounting surface, two clip arms  84  on an opposite side  80   b  of the clip plate, and a hole  84  for passing a mounting fastener such as a wood screw through the plate  82 . A contact adhesive may be provided on the contact side  80   a  of the plate  82 , to facilitate installation by holding the clip  80  on the mounting surface while a fastener is installed through the plate  82 . 
     The strip lighting system  10  as described to this point makes use of mounting lugs  42  and possibly mounting clips  80  for fastening the cable  10  and lamp sockets  14  to a mounting surface. As an alternative, a track  90  is provided which can be fastened to a mounting surface for holding cable  12  and lamp sockets  14 , as shown in  FIGS. 26-28 . 
     Turning to  FIGS. 26-28  track  90  has two track side walls  92  and a-track bottom  94 , and is attached to a mounting surface with track fasteners such as screws passing through holes spaced along the track bottom. Track  90  interlocks with and retains lamp sockets  14  inserted between the track side walls  92 . A side ridge  92   a  along the interior of each track side wall mates with side grooves  15  formed on the outside of socket bottom side walls  24   a,  as best seen in  FIG. 28 . The lamp socket  14  makes snap retentive engagement in track  90  when pressed down into the track, to hold the lamp socket in the track. The track may be a continuous extrusion of plastic or other suitable material. A translucent or transparent lens  96  can be installed over the track  90 , for example, also by snap interlocking of the lens edges  96   a  with the sides  92  of the track, as shown in  FIG. 28 . 
       FIGS. 29-31  show an alternate track configuration  90 ′ suitable for mounting along a wall for a wall light wash effect. Track  90 ′ differs from track  90  in that one of the side walls  92  is taller than the other side wall and the lens  96 ′ covers a 90° arc in cross section rather than approximately a 180° arc as in lens  96  of  FIG. 28 . 
       FIGS. 32-34  show a chaser type track  90 ″ similar to track  90  but provided with a chaser wire guide  98  on an outer side of each of the side walls  92  for guiding power supply chaser wires W along the outside of the track. The wire guides  98  are formed integrally with the track  90 ″, for example, as integral part of a track extrusion. The chaser wire guides  98  have an arcuate, generally quarter circular cross section with a concave underside  98   a,  generally conforming to the cross sectional curvature of an insulated electrical chaser wire W, for holding and containing the wire under the wire guide  98  and against a mounting surface S underlying the track bottom  94 . The chaser type track  90 ″ is typically used in lighting installations where two consecutive track sections are powered by separate power transformers but both transformers are mounted at one end of track  90 ″. A first power transformer supplies power to cable  12  of chaser track  90 ″ and the exterior chaser wires carry electrical power from the second power transformer along track  90 ″ to the second section of track which starts at the opposite end of the chaser track  90 ″, where the exterior wires are connected to a cable  12  contained in the second section of track. This arrangement becomes necessary where the first section of track consumes the rated power output of one transformer and a second transformer is needed to power the second track section, but where for esthetic or practical considerations it is desirable to mount both transformers in one location at one end of the two continuous tracks. 
       FIGS. 19-21  show a power block  100  where a conventional four-terminal screw-down terminal strip  102  is provided with a terminal strip housing  104 . Housing  104  has a housing bottom  106  containing the terminal strip  102  and a housing cover  108  hinged at  110  to housing bottom  106 . The housing bottom  106  has two housing bottom side walls  106   a  and two open ends  112  between side walls  106   a.  A clasp  114  is provided for fastening the housing cover  108  closed to housing bottom  106  as in  FIG. 19 . A pair of grooves  116  along the exterior of housing bottom side walls  106   a  are provided for making retentive engagement with side ridges  92   a  of track  90  so that the power block  100  can be snap mounted into the track  90  in a manner similar to the lamp sockets  14 , as explained above. The power block  100  is used for making electrical power connections to and from power cable  12 . One end of cable  12  is stripped to expose conductors  16  and each conductor  16  is inserted into a corresponding terminal on one open end  112  of power block  100 . The conductors are fastened by tightening the corresponding two terminal screws of terminal strip  102 . Two other wires, for example, two power carrying wires from a power transformer are inserted in the other two terminals on the opposite open end  112  and fastened there with the other two terminal screws. Terminal strip  102  is a commonly available item and its details are not shown in the drawings for simplicity. 
       FIGS. 22-23  show a junction box  120  used to splice electrical wires to cable  12 . Box  120  has a slot  122  in one side  124   a  of the box for admitting and end of power cable  12 . Cable  12  is clamped to the box between clamping bar  124  and lip  126  of the box  120 . A dimple  124   a  in the clamping bar is pressed down against the cable insulation by clamp screws  128  threaded for urging the clamping bar  124  against lip  126 . The junction box  120  has knockouts  130  in each of the three remaining sides  124   b,c,d  of the box for admitting electrical wires to be spliced to the end of cable  12  in the box. The box is closed by a box cover  130  fastened with two screws  132 . 
       FIGS. 24-25  show another junction box  120 ′, where elements similar to those of box  120  in  FIGS. 22-23  are designated by similar numerals. Box  120 ′ is provided with three cable slots  122  in three box sides  124 ′ a,b,c  for admitting one, two or three cable  12  ends into the box. Each cable slot  122  is provided with a corresponding cable clamping arrangement analogous to that described in connection with  FIGS. 22-23  and designated by similar numerals. Box  120  is useful, for example, for making L or T junctions between two or three cables  12  and for connecting electrical supply wires admitted-through knockouts  130  to such junctions. 
     While particular embodiments of the invention have been explained and illustrated for purposes of clarity and example, it must be understood that many changes, modifications and substitutions will become apparent to those having only ordinary skill in the art without thereby departing form the scope of the invention.