Patent Publication Number: US-11655971-B2

Title: Connector system for lighting assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 17/062,755, entitled “Connector System for Lighting Assembly” and filed Oct. 5, 2020, which is a continuation application of U.S. patent application Ser. No. 16/687,233, entitled “Connector System for Lighting Assembly” and filed Nov. 18, 2019, now U.S. Pat. No. 10,794,581 issued on Oct. 6, 2020, which is a continuation of U.S. patent application Ser. No. 16/394,970, entitled “Connector System For Lighting Assembly” and filed Apr. 25, 2019, now U.S. Pat. No. 10,480,764 issued on Nov. 19, 2019, which is a continuation application of U.S. patent application Ser. No. 15/401,537, entitled “Connector System For Lighting Assembly” and filed Jan. 9, 2017, now U.S. Pat. No. 10,302,292 B2, issued on May 28, 2019, which claims the benefit of U.S. Provisional Patent Application No. 62/276,075, entitled “Connector System For Lighting Assembly” and filed Jan. 7, 2016, and U.S. Provisional Patent Application No. 62/422,521, entitled “Connector System For Lighting Assembly” and filed Nov. 15, 2016, which are hereby incorporated by reference in their entirety herein. 
    
    
     FIELD 
     This invention relates to lighting and, more particularly, to light emitting diode (LED) illumination as well as tubular lighting assemblies. 
     BACKGROUND 
     Over the years various types of illuminating assemblies and devices have been developed for indoor and/or outdoor illumination, such as torches, oil lamps, gas lamps, lanterns, incandescent bulbs, neon signs, fluorescent bulbs, halogen lights, and light emitting diodes. These conventional prior art illuminating assemblies and devices have met with varying degrees of success. 
     Incandescent light bulbs create light by conducting electricity through a thin filament, such as a tungsten filament, to heat the filament to a very high temperature so that it glows and produces visible light. Incandescent light bulbs emit a yellow or white color. Incandescent light bulbs, however, are very inefficient, as a high percentage of energy input is lost as heat. 
     Fluorescent lamps conduct electricity through mercury vapor, which produces ultraviolet (UV) light. The ultraviolet light is then absorbed by a phosphor coating inside the lamp, causing it to glow, or fluoresce. While the heat generated by fluorescent lamps is much less than its incandescent counterparts, energy is still lost in generating the UV light and converting UV light into visible light. If the lamp breaks, exposure to mercury can occur. Linear fluorescent lamps are often five to six times the cost of incandescent bulbs but have life spans around 10,000 and 20,000 hours. Some fluorescent lights flicker and the quality of the fluorescent light tends to be a harsh white due to the lack of a broad band of frequencies. Most fluorescent lights are not compatible with dimmers. 
     Conventional fluorescent lights typically utilize a bi-pin/2-pin means on the tubular body that mechanically supports the body in an operative state on lamp holders of the ceiling lighting fixture and effects electrical connection of the illumination source to a power supply. A ballast associated with the lighting fixture converts AC line voltage to the DC power provided to the florescent tube. The ballast also reduces the power supply to a voltage level suitable for use in a florescent tube. A starter circuit for providing a voltage pulse is needed to cause current to conduct through the ionized gas in the fluorescent tube. 
     Light emitting diode (LED) lighting is particularly useful. Light emitting diodes (LEDs) offer many advantages over incandescent and fluorescent light sources, including: lower energy consumption, longer lifetime, improved robustness, smaller size, faster switching, and excellent durability and reliability. LEDs emit more light per watt than incandescent light bulbs. LEDs can be tiny and easily placed on printed circuit boards. LEDs activate and turn on very quickly and can be readily dimmed. LEDs emit a cool light with very little infrared light. LEDs come in multiple colors which are produced without the need for filters. LEDs of different colors can be mixed to produce white light. 
     The operational life of some white LED lamps is 100,000 hours, which is much longer than the average life of an incandescent bulb or fluorescent lamp. Another important advantage of LED lighting is reduced power consumption. An LED circuit will approach 80% efficiency, which means 80% of the electrical energy is converted to light energy; the remaining 20% is lost as heat energy. Incandescent bulbs, however, operate at about 20% efficiency with 80% of the electrical energy lost as heat. 
     Linear LED tube lighting products for replacing fluorescent lighting typically comprise an array of LEDs mounted on one or more circuit boards. The LED boards are mounted on an elongate heat sink comprising a heat conducting material such as aluminum. The LED circuit boards are in thermal contact with the heat sink, but electrically isolated from the heat sink. The LED tube lamp may include internal driver module containing circuitry for converting AC line current to DC current and controlling the voltage applied to the LEDs. The internal driver circuitry can be designed specifically to meet the electrical requirements of the LED circuit boards, thus overcoming potential problems associated with using the existing local ballast originally designed for powering fluorescent lamps. In some designs, however, an external local ballast is used. The high power LEDs, as well as any internal driver module, generate heat that must be dissipated by the heat sink. To facilitate heat dissipation to the atmosphere, the heat sink is typically disposed such that its external surface forms a portion of the outer surface of the tube lighting assembly. The lighting assembly is installed such that the heat sink faces upward toward the ceiling lighting fixture. The remaining circumference of the tube comprises a translucent or transparent lens cover through which the generated light is emitted. The lens cover faces towards the space to be illuminated when the LED lighting assembly is installed in a ceiling or other lighting fixture. 
     The linear LED lamp heat sink is typically fabricated of an electrically conductive metallic material such as aluminum or aluminum alloys. These materials dissipate heat efficiently without a significant increase in surface temperature. The heat sink itself, as well as the printed circuit LED boards and other electrical components within the linear LED tube assembly, present a safety hazard without proper electrical grounding. This is because the line voltage or voltage input to the LED boards could be applied to the heat sink in the event of a short circuit, for example, if the insulation between the LEDs and/or internal driver circuitry and the heat sink is inadequate or deteriorates during use. This could lead to other components within the assembly overheating and creating a fire hazard. It also creates an electrical shock hazard should the user come into physical contact with the heat sink when inspecting the installed lamp. The electrical components within the lamp, such as LEDs and driver circuits, are also susceptible of being damaged in the event of a power surge. With the recent introduction of sensors, cameras, control and data communications circuitry and other “smart lighting” components into linear LED lamp formats, a comprehensive protective grounding system is required. 
     One type of LED tube lamp is designed for the insert and rotate type lamp holders mounted on conventional fluorescent ceiling lighting fixtures, known in the industry as “tombstone” lamp holders. Such lamp holders are designed to engage electrical power pins projecting in cantilever fashion from the ends of a cylindrical shaped fluorescent tube lamp, or LED replacement tube lamp. The exposed pins on the ends of the linear LED tube are susceptible to damage during distribution and installation. The lamp body must be situated in a first angular orientation to direct the pins into the lamp holders mounted on a support/reflector and is thereafter turned to effect mechanical securement and electrical connection. Installation requires a precise initial angular orientation of the body and subsequent controlled repositioning thereof to simultaneously seat the pins at the opposite ends of the body. Often one or more of the pins are misaligned during this process so that electrical connection is not established. The same misalignment may cause a compromised mechanical connection whereupon the body may escape from the connectors and drop so that it is damaged or destroyed. 
     Further, the connectors on the support/reflector are generally mounted in such a fashion that they are prone to flexing. Even a slight flexing of the connectors on the support might be adequate to release the pins at one body end so that the entire body becomes separated. The conventional bi-pin and tombstone lamp holder connector means was created for very lightweight fluorescent lighting and not designed for LED tubular lighting that has additional weight due to the required heat sink and PCB boards. The weight of the body by itself may produce horizontal force components that wedge the connectors on the support/reflector away from each other so that the body becomes precariously situated or fully releases. 
     U.S. Pat. No. 8,434,891 to Ham proposes a LED tube and socket assembly adapted from the conventional insert and rotate type lamp holder system. The disclosed LED tube features a three pin interface projecting from each end of the tube wherein a middle pin is connected to the heat sink. The lamp holder includes a ground terminal, which receives the middle pin and in turn is connected to an external ground via a ground strap. While this approach provides a grounded heat sink, it does not overcome the above-mentioned problems associated with utilizing external pins in an insert and rotate lamp holder for securing linear LED tube lamps. It does not provide ground protection for the electrical components and circuitry of the lamp. 
     Moreover, the user is not prevented from inadvertently installing the three-pin lamp ends in a conventional, non-grounded tombstone holder rather than the grounded counterpart replacement holders proposed by Ham. Doing so results in a non-grounded lamp, although visually the installation looks nearly identical to a properly grounded lamp. There is no reliable means of assuring that the holders are replaced and the installation properly performed, and it is difficult to determine by visual inspection whether an installation was performed properly to create a safe grounded system. It is impractical to disassemble the system to check that the conventional fluorescent lamp holders were replaced with grounded lamp holders and that ground straps were connected to the system ground. This presents a significant difficulty for end users, lighting maintenance personnel, building inspectors, safety regulators and others desiring to confirm that replacement LED tube lamps are safely grounded. These difficulties are even more pronounced in commercial environments, such as retail space, warehouses and office buildings, whose overhead lighting systems may utilize hundreds or even thousands of linear tube lamps. 
     An alternative snap-fit connector system adapted for LED linear tubes is shown in U.S. Patent Application Publication 2014/0293595, by the same applicant of the subject application, and is incorporated as if reproduced in its entirety herein. The tubular LED lighting assembly has at least one LED emitter board within the body; and first and second connectors respectively at the first and second body ends that are configured to secure the lamp on a support fixture. The first connector has cooperating first and second parts. The first connector part is integrated into an end cap assembly of the lamp body. The second connector part is configured to be on a support for the tubular lighting assembly. 
     The first and second connector parts respectively have first and second surfaces. As the second connector parts connector part is received within an opening of the end cap assembly, the first and second surfaces are placed in confronting relationship to prevent separation of the first and second connector parts as an incident of the first connector part moving relative to the second connector part from a position fully separated from the second connector part in a substantially straight path that is transverse to the length of the lamp body. The snap-fit connection does not utilize exposed pins to mechanically secure the lamp ends to the support and is effected by a linear motion rather than an insert and rotate technique. The first end cap assembly includes at least a first connector board. The connector board comprise generally L-shaped pins housed within the end cap assembly, each having a first portion extending in a direction generally parallel to the length of the body and a second portion extending in a direction traverse to the length of the body and towards the second connector part when said first connector part is moved towards the second the second connector part and into the engaged position. The conductive components on each of the first and second connector parts electrically connect to each other to form an electrical path between the illumination source and an externa power supply as an incident of the connector parts being moved into the snap-fit engaged configuration. 
     The above-mentioned snap-fit connector system addresses some of the problems associated with the use of conventional tombstone type lamp holders for securing LED tube lamps to lighting fixtures. However, it maintains the LED tube lamp in an operating state without providing a means for ground protecting the LED tube heat sink or the internal electrical components of the lamp, thus creating safety and reliability issues for the lamp installation. There is a need for a connector system designed for the unique needs of LED lamp technology that alleviates all safety concerns and provides a safe, reliable and convenient solution that will allow the benefits of LED lamp technology to be fully realized and can be implemented in a cost-effective manner. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a fragmentary, perspective view of an elongate tubular lighting assembly, and showing cooperating connector parts at one end of a body on or within which there is a source of illumination; 
         FIG.  2    is a view as in  FIG.  1    with the connector parts fully separated from each other; 
         FIG.  3    is a view as in  FIG.  2    showing cooperating connector parts at the opposite end of the body; 
         FIG.  4    is an enlarged, end view of the connector parts shown in the relationship of  FIG.  2   ; 
         FIG.  5    is a view as in  FIG.  4    with the connector parts joined in an assembled configuration; 
         FIG.  6    is an exploded, perspective view of an end cap assembly consisting of the connector parts in  FIG.  2    and a connector board for the source of illumination; 
         FIG.  7    is a view as in  FIG.  6    with the parts assembled; 
         FIG.  8   a    is a perspective view of tubular lighting assembly, and showing cooperating connector parts at each end of the body configured to connect to an external power source at each end of the body; 
         FIG.  8   b    is a perspective view of tubular lighting assembly, and showing cooperating connector parts at each end of the body, with one set of cooperating connector parts configured to connect to an external power source; 
         FIG.  9    is a perspective view of tubular lighting assembly, and showing cooperating connector parts at one end of the body, configured to connect to an external power source and a connector sleeve at the other end of the body; 
         FIG.  10    is a fragmentary, perspective view of an elongate tubular lighting assembly, and showing cooperating connector parts at one end of a body and including cooperating ground protection components; 
         FIG.  11    is a fragmentary, perspective view of an elongate tubular lighting assembly, and showing cooperating connector parts at one end of a body and including alternative cooperating ground protection components; 
         FIG.  12    is a fragmentary, perspective view of an elongate tubular lighting assembly, and showing cooperating connector parts at one end of a body and including alternative cooperating ground protection components; 
         FIG.  13    is a fragmentary, perspective view of a multi-sided elongate tubular lighting assembly, and showing cooperating connector parts at one end of a body and including alternative cooperating ground protection components; 
         FIG.  14    is a fragmentary, perspective view of an elongate tubular lighting assembly, and showing cooperating connector parts comprising a connector sleeve at a no power end of a body and including cooperating ground protection components; and 
         FIG.  15    is a fragmentary, perspective view of an elongate tubular lighting assembly, and showing cooperating connector parts comprising a connector sleeve at a no power end of a body and including alternative cooperating ground protection components. 
         FIG.  16    is a fragmentary, perspective view of another embodiment of a multi-sided elongate tubular lighting assembly, and showing cooperating connector parts at one end of a body and including alternative cooperating ground protection components; 
         FIG.  17    is a fragmentary, perspective view of another embodiment of a generally cylindrical elongate tubular lighting assembly, and showing cooperating connector parts at one end of a body and including alternative cooperating ground protection components; 
         FIG.  18    is a perspective view of the cooperating connector parts in  FIG.  17    in an assembled configuration; 
         FIG.  19   a    is an end view of the cooperating connector parts in  FIG.  17    in a partially assembled configuration; 
         FIG.  19   b    is an end view of the cooperating connector parts in  FIG.  17    in a fully assembled configuration; 
         FIG.  20   a    is an end view of one of the connector parts in  FIG.  17   ; 
         FIG.  20   b    is a side view of the connector part in  FIG.  20     a;    
         FIG.  21   a    is a side view of the other connector part in  FIG.  17   ; and 
         FIG.  21   b    is an end view of the connector part in  FIG.  21     a.    
         FIG.  22    is perspective view of a linear lighting assembly, and showing cooperating connector parts at each end of the body, with one set of cooperating connector parts configured to connect to an external power source with isolated ground protection. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any such alterations and further modifications in the illustrated devices, and such further applications of the principles of the invention as illustrated herein are contemplated as would normally occur to one skilled in the art to which the invention relates. 
     There is a need for an improved lamp holder and connector system that address all safety issues and provides a grounded LED lighting system in the linear tube format that is widely deployed throughout the lighting industry. As used herein, the terms “LED tube lamp” and “linear LED lamp” and similar variants are used interchangeably to describe LED lamps having at least one LED board mounted on an externally exposed heat sink having a narrow and elongated overall profile and with optional elongated optical lens, and designed for removable mounting to a variety of lighting fixture housings. While the overall form factor of such lamps is ordinarily generally similar to that of conventional fluorescent tube lamps, the use of these terms is not intended to limit the scope of the disclosed or claimed subject matter to lamps having any particular lateral cross-sectional shape or to require a fully enclosed outer tubular structure. 
       FIGS.  1  to  7    illustrate an available snap-fit connector system for linear LED tube lighting. The lamp comprises an elongate tubular body portion  10  including a metallic heat sink  12  extending throughout a generally upward facing portion of the circumference of the tubular body, and a transparent or translucent lens portion  14  extending throughout a generally downward facing portion of the circumference of the tubular body. The heat sink is preferably formed of an aluminum alloy, although other thermally conductive materials may be used. At least one LED emitter panel comprising a printed circuit board mounting a series of LEDs is mounted to the heat sink internal to the tubular body. Heat generated by the LEDs conducts through the emitter panel to the heat sink. The heat sink of the illustrated lamp is multi-sided with a generally triangular cross-sectional geometry in a plane perpendicular to the length of the lamp body, providing two mounting surfaces for supporting multiple LED emitter panels in a V-orientation. End cap assemblies disposed at the opposite lamp ends have a corresponding triangular cross-section in a plane perpendicular to the length of the body. 
     The available system mechanically secures the LED tube lamp to a support and electrically connects it to an external power supply, but leaves the lamp heat sink and internal electronic components in an ungrounded state. As can be seen in  FIGS.  1 - 3   , a first connector  100  at the first end  20  of the body  10  is made up of a first connector part  110  and a second connector part  120 . A second connector  400  is provided at the second end  30  of the body  10  and is made up of a third connector part  410  and a fourth connector part  420 . The body of the connector parts are formed of plastic or other non-conductive material and are preferably manufactured using conventional injection molding techniques. 
     The first and second connectors  100 ,  400  are configured to maintain the body  10  in an operative state on a support  50  that may be in the form of a reflector, or otherwise configured. The first connector part  110  is part of a first end cap assembly  112  that is provided at the first body end  20 . The second connector part  120  is provided on the support/reflector  50 . The third connector part  410  is provided at the second end  30  of the body  10 , with the fourth connector part  420  provided on the support/reflector  50 . The body includes at least one LED emitter panel providing a source of illumination, which is electrically connected to a power supply through the first connector  100 . 
     As shown in  FIG.  4   , second connector part  120  has oppositely opening slots  129 ,  129 ′. The slots cooperate with the reflector tabs  52 ,  54  as illustrated in  FIG.  1   . That is, the tabs  52 ,  54  are formed so that they can slide through the slots  129 ,  129 ′ whereby the second connector part  120  and support/reflector  50  can be press connected starting with these parts fully separated from each other. A simple sliding movement lengthwise of the body  10  will fully seat the tabs  52 ,  54  that become frictionally held in the slots  129 ,  129 ′. The fourth connector part  420  also includes slots that provide for releasable connection to tabs of the support/reflector  50  in substantially the same way. 
     As shown in  FIGS.  1 ,  6  and  7   , first end cap assembly  112  which forms the first connector part  110  consists of a first, cup-shaped receptacle  119  into which the first end of the body extends. The first end cap assembly  112  is shaped to accommodate a multi-sided heat sink having a generally V-shaped cross-section for supporting multiple LED emitter boards, and an internal driver board. Other end cap and heat sink configurations are possible. 
     In  FIG.  4   , the first connector part  110  is shown in a position fully separated from the second connector part  120 . In  FIG.  5   , the first connector part  110  is shown moved relative to the second connector part  120  from the fully separated position in a substantially straight path, as indicated by the upward pointing arrow, transverse to the length of the body  10 , into the engaged upward facing wall  114  bounded by an edge. Second connector part  120  has a first bendable part  122 . The second connector part  120  is configured so that the first bendable part  122  is engaged by the edge of the opening  116  and progressively cammed from a holding position, as shown in solid lines in  FIGS.  4  and  5   , towards an assembly position, as shown in dotted lines in each of  FIG.  4    and  FIG.  5   , as the lamp end  20  and first connector part  110  is moved upward to and into the engaged position. The first bendable part  122  moves from the assembly position back towards the holding position with the first part realizing the engaged position. 
     The first connector part  110  has a wall  114  through which the opening  116  is formed. A first surface  117  is a portion of the inner surface of this wall  114 . A second surface  124  is defined by a boss  126  on the bendable part  122 . The wall  114  has a third surface  118  on its opposite surface that faces towards a fourth surface  128  on the second connector part  120 . The wall  114  resides captively between the second and fourth surfaces  124 ,  128  with the first connector part  110  in the engaged position to maintain this snap-fit connection. 
     As can be seen in  FIG.  2   , first bendable part  122  is joined to the leading end  127  of the second connector part  120  through a live hinge  125 . The second connector part  120  has an actuator  121 , in this embodiment on the first bendable part  122  remote from the hinge  125 , that can be pressed in the direction of the horizontal arrow in  FIG.  4    with the first connector part  110  in the engaged position, thereby to move the first bendable part  122  towards its assembly position, as shown in dotted lines in  FIGS.  4  and  5   , to allow the surface  124  to pass through the opening  116  so that first connector part  110  can be separated from the second connector part  120 . The second connector part  120  has a second bendable part  122 ′ on an opposite side that is configured the same as the first bendable part  120  and cooperates with the edge of opening  116  in the same way that the first bendable part  120  cooperates with the edge in moving between corresponding holding and assembly positions. An actuator  121 ′ is situated so that the installer can grip and squeeze the actuators  121 ,  121 ′, as between two fingers, towards each other, thereby changing both bendable parts  122 ,  122 ′ from their holding positions into their assembly positions. 
     The second connector  400  has third and fourth connector parts  410 ,  420  that are respectively structurally the same as the first and second connector parts and interact with each other mechanically at the second end  30  of the body  10  in the same way that the first and second connector parts  110 ,  120  interact with each other at the first end  20  of the body. The first and second connectors  100 ,  400  are configured to maintain the body  10  in an operative state on a support  50  that may be in the form of a reflector, or otherwise configured. 
     In the embodiment shown, at least the first end  20  of the LED tube lamp is adapted to receive power from an external power supply. As shown in  FIGS.  6  and  7   , the receptacle  119  may receive an end connector board  60  having L-shaped electrical connector terminals  62 ,  64  thereon that cooperate with connector assemblies  72 ,  74  having wires that extend through second connector part  120  to establish electrical connection between the board  60  and the power supply. The connector terminals  62 ,  64  may be mechanically and electrically connected to the board  60 , and the board includes traces to form electrical paths from the connector terminals  62 ,  64  to terminals such as terminals  66 . The terminals  66  cooperate with pins extending from LED emitter boards, driver circuit boards or other electrical components to provide power to such components. Alternatively, the connector terminals  62 ,  64  may electrically connect to the LED emitter boards and/or other electrical components of the LED lamp system via one or more wires. The L-shaped electrical connector terminals  62 ,  64  of connector board  60  each have a first portion extending in direction generally parallel to the length of the body and a second portion extending in a direction traverse to the length of the body and towards the second connector part  120 . When said first connector part  110  is moved towards the second the second connector part and into the engaged position, the first and second connector parts  110 ,  120  can be mechanically snap-connected, and connector assemblies  72 ,  74  are also press fit into electrical connection with the connector terminals  62 ,  64  as an incident of the first connector part  110  moving from its fully separated position into its engaged position. 
       FIG.  8   a    illustrates an installation using a snap-fit connector system of this type in which power is supplied to both ends of the linear LED tube lamp body  10 . In  FIG.  8   a   , the connector is shown for a linear LED tube lamp of a generally circular cross-section. Snap-fit connectors  100  and  400  are provided at opposite ends of the lamp comprising first and second connector parts  110 ,  120  and third and fourth connector parts  410 ,  420  respectively. The depicted lamp is designed to be connected to and receive power from an external power supply at both lamp ends, as shown in  FIG.  8   a   . The connector system components at each end of the lamp thus includes both the mechanical and electrical connector components described above. Some LED lamps are configured to connect to the external power supply at only one end. As illustrated in  FIG.  8   b   , for a lamp of this type shown as lamp  11 , the second connector  400  may include only the components needed to mechanically connect third connector part  410  of second end cap assembly to fourth connector part  420 . In other words, the second end cap assembly and the fourth connector part  420  need not include electrical connector terminals and may be provided without a means for connecting to the power supply. 
     The connector systems described thus far for powering the internal components of the lamp leave the internal components, and the externally exposed lamp heat sink, in an ungrounded condition. There is a risk of damaging the internal components in the event of a power surge, and the heat sink presents a potential electric shock risk and/or fire hazard if applied power leaks to the heat sink as a result of a short circuit condition. 
       FIG.  9    illustrates an alternative, improved connector system adapted for single end power linear LED tube lamps in which only one end of the lamp is configured to connect to and receive power from an external power supply. In this system, the end  30  of the LED tube lamp  12  shown, is adapted to receive power through connector assemblies  72  and  74 . It is secured to support  50  by means of connector  400  consisting of third connector part  410  having an opening in its sidewall and fourth connector part  420  having moveable components for making a snap-fit connection with the sidewall, as described above with reference to the  FIGS.  1  to  7  and  8     a . The opposite end  35  of lamp  12  includes an end cap assembly  510  of cylindrical shape having a receptacle into which the second end of lamp  12  inserts. The end cap assembly  510  need not include an opening in its side wall, as it does not engage a male snap-fit connector part of the type depicted as fourth connector part  420  for securing the first lamp end  30 . 
     The system further includes plastic connector sleeve  520 , which is adapted to mount to support  50 . A base portion  522  of connector sleeve  520  includes slots  530  on opposite sides thereof into which tabs  52 ,  54  of support  50  slide so that connector sleeve  520  can be secured to support  50 . The base portion  522  extends toward sleeve portion  524  comprising a continuous sidewall  526  and end wall  528 , which form a receptacle having an open end facing towards the opposite fourth connector part  420  and sized to receive the second end cap assembly  510  of the LED lamp. The sleeve portion  524  is preferably of a cross-sectional shape that conforms to the cross-sectional shape of end cap assembly  510 , which is circular in the illustrated embodiment. Connector sleeves comprising a sleeve portion of other cross-sectional geometries, such as generally triangular, square or rectangular, are also contemplated for use with other lamps having corresponding end cap cross-sectional geometries. In one preferred form, the sleeve forms a receptacle of a generally triangular cross-section for receiving a generally triangular end cap assembly of a lamp comprising a multi-sided heat sink mounting multiple LED emitter boards such as the lamp illustrated in  FIGS.  1  to  3   . 
       FIG.  9    shows the fourth connector part  420  of connector  400  and connector sleeve  520  mounted to support  50  at opposite ends of a light fixture. LED tube lamp  12  may be installed in the fixture by inserting the end cap assembly  510  at the end  35  linearly along the length of the lamp body in the direction of the horizontal arrow into the receptacle of connector sleeve  520 . The connector sleeve is preferably sized so that end cap assembly  510  is easily guided into the receptacle, where it is supported in the vertical direction yet adjustable in the horizontal direction. Next, the third connector part  410  of the end cap assembly at the opposite end  30  is adjusted so that its opening is aligned with the fourth connector part  420 . In the case of a cylindrical lamp, this may also require rotating the lamp about its longitudinal axis to radially aligning the female opening of third connector part with the male portion of fourth connector part at the power end. The third connector part is then moved upward in the direction of the vertical arrow towards fourth connector part  420  so as to guide the fourth connector part  420  into snap-fit connection with third connector part  410 . Securing the snap-fit connection at the power end  30  of the lamp locks the lamp at its proper rotational orientation and prevents the lamp from backing out linearly from connector sleeve  520 , and the lamp is thus securely maintained in an operational state. To remove an installed lamp, the snap-fit connection may be released using the actuators as previously described, which allows withdrawing the end cap assembly  510  at end  35  from the receptacle of connector sleeve  520 . 
     This connector system offers potential advantages compared to the alternative approach of deploying a power enabled snap-fit connector at the power end of the lamp and modified no power snap-fit connector at the opposite no power end. It eliminates the need to manufacture and distribute alternative versions of the snap-fit connector for power and no power applications. It also facilitates simplification of LED tube lamp design, as the no power end  35  requires only a simple end cap without any modifications to accommodate a snap-fit connection system or external bi-pin terminals adapted for conventional tombstone lamp holders. The connector sleeve  520  is easily manufactured and contains no moving parts. 
     Moreover, the sleeve  520  provides convenience to the lamp installer and a more efficient installation methodology. With standard linear LED tube lamps typically ranging from 2 to 8 feet in length, it is cumbersome to properly align the cooperating components into the proper engaged position while handling a portion of the lamp that is significantly displaced from the lamp end being installed. Thus, lamp installation typically requires the installer to grasp a first end of the lamp and position it into engagement with its corresponding lamp holder, whether a snap-fit connector or rotating tombstone lamp holder, and then move to a position proximate the opposite end of the lamp to manipulate the opposite end into engagement with its lamp holder. Using the connector sleeve  520 , however, both ends of the lamp may be installed by manipulating the lamp from the power end. While grasping the lamp near the power end  30 , the installer may guide the opposite no power end  35  into the receptacle opening of connector sleeve  520 . This requires only minimal dexterity and skill compared to the more precise positioning and controlled movements needed to guide the components of the snap-fit or tombstone type connector system together. After the no power end is seated in the receptacle of the connector sleeve, the installer may adjust the linear and angular position of third connector part  410  at the power end  30  as necessary to align its connector opening with fourth connector part  420  while the opposite end  35  remains seated in the connector sleeve. While remaining at the same location, the installer then moves the lamp end  30  directly upward from the separated position and into snap-fit engagement with fourth connector part  420  pre-mounted on support  50 . Potentially significant time and associated labor savings may be achieved with this system and installation method, especially in commercial environments requiring installation of hundreds or potentially thousands of LED tube lamps. 
     With connector systems suitable to mechanically and electrically connect linear LED tube lamps to a support having thus been described, the following discloses improved connector systems capable of providing ground protection to the lamp heat sink and/or internal electronic components.  FIG.  10    is directed to a snap-fit connector system for a linear LED tube lamp that includes an integrated grounding system for providing ground protection to the LED tube heat sink. LED tube lamp  250  comprises an elongate tubular body portion including a metallic heat sink  254  extending throughout a generally upward facing portion of the circumference of the tubular body, and a transparent or translucent lens portion  252  extending throughout a generally downward facing portion of the circumference of the tubular body. The heat sink is preferably formed of an aluminum alloy, although other thermally conductive materials may be used. At least one LED emitter panel  270  comprising a printed circuit board mounting a series of LEDs is mounted to the heat sink internal to the tubular body. Heat generated by the LEDs conducts through the emitter panel to the heat sink. The heat sink may include fins  255  extending along its length to increase the effective surface area for transfer of heat to the atmosphere. The LED lamp  250  may include an internal ballast or driver module or may alternatively utilize an external ballast associated with the lighting fixture. Heat sink  254  has a generally semi-circular cross-section in a plane perpendicular to the length of the lamp, with support wall  259  extending across the internal region thereof to provide a mounting surface for LED emitter panel  270 . Other heat sink geometries are also contemplated, including, for example, a configuration such as the one illustrated in  FIG.  13    comprising multiple support walls arranged in a generally V-shape and lying in intersecting planes for supporting multiple LED emitter panels arranged to distribute light over a wide area. 
     With further reference to  FIG.  10   , LED lamp  250  is mounted at its first end to a support  50  of a lighting fixture by means of snap-fit connector system  200  comprising first connector part  210  and second connector part  220 . Several aspects of the components of the snap-fit connector system of  FIG.  10    for securely connecting LED lamp  250  to support  50  are substantially the same structurally as described above with reference to the snap-fit system illustrated in  FIGS.  1 - 7   . Thus, second connector part  220  is provided on the support/reflector  50 . The support  50  may be a reflector portion of an existing ceiling lighting fixture of the type conventionally used for linear fluorescent tube lighting. The connector system of the invention may be utilized in other types of lighting fixtures secured to an overhead ceiling grid or to another structure. The LED emitter panel  270  providing a source of illumination is electrically connected to a power supply through the connector system  200 . The second connector part  220  can be press connected to the support  50  by means of oppositely opening slots that cooperate with the support tabs  52 ,  54 . Of course other releasable, and potentially permanent, connections are contemplated. 
     The first connector part  210  is part of a first end cap assembly  214  that is provided at the first end of LED lamp  250 . The first end cap assembly  214  is formed of plastic or other non-conducting material and comprises cylindrical side wall  212  extending from circular end wall  230 . First end cap assembly  214  forms a cup-shaped receptacle into which the first end of the body of LED lamp  250  extends. An opening  216  is formed in side wall  212  to receive a portion of second connector part  220 . 
     The second connector part  220  has a pair of bendable parts  222  on opposite sides thereof, each operable through hinge  225 , which are engaged by the edge of the opening  116  and progressively cammed from a holding position towards an assembly position as the first connector part  210  is moved up to and into the engaged position. The first bendable parts  222  move from the assembly position back towards the holding position with the first part realizing the engaged position. The wall  214  resides captively between surfaces of the first connector part  210  in the engaged position to maintain this snap-fit connection. A pair of actuators  221  on opposite sides of second connector part  220  can be pressed to move the first bendable parts  222  towards its assembly position, in the same manner shown in dotted lines in  FIGS.  4  and  5   , to allow them to pass through the opening  216  so that first connector part  210  can be separated from the second connector part  220 . 
     As  FIG.  10    illustrates, the receptacle of end cap assembly  214  may receive an end connector board  260  having L-shaped electrical connector components  262 ,  264  thereon that cooperate with connector assemblies  72 ,  74  having wires that extend into the second connector part  220  and connect to a power supply. The connector components  262 ,  264  may connect to LED emitter board  270  by means of wires  266  and may similarly provide power to other internal components of LED tube lamp  250 . In one aspect, wires  266  connect to an internally mounted driver module to provide AC line voltage which the driver module converts to DC voltage supplied to the LED emitter board and optionally other internal componentry. Although the embodiment illustrated in  FIG.  10    utilizes internal wire connections, the end connector board  260  may alternatively be in the form of a printed circuit board (PCB) connector containing male or female electrical terminals for connecting to corresponding terminals associated with LED emitter board  270 , a driver circuit or other internal components of the lamp to provide a no-wire design. In both approaches, connector components  262 ,  264  provide an electrical path over which electrical power from a power supply is provided to the LED emitter board  270  and optionally other internal components. The L-shaped electrical connector components  262 ,  264  on the connector board  260  each have a first portion extending in direction generally parallel to the length of the body and a second engagement portion extending in a direction traverse to the length of the body and towards the second connector part  220  when said first connector part  210  is moved towards the second the second connector part and into the engaged position. 
     Heat sink  254  has a planar end face  258  at a first end thereof defining a pair of apertures  257 . Connector end board  260  includes a pair of corresponding apertures  253  aligned with heat sink apertures  257 . End wall  230  of first end cap assembly  214  defines corresponding aligned apertures  236 . The end cap assembly  214  and end connector board  260  may be secured to heat sink  254  at the first end of LED tube lamp  250  with a pair of metallic fasteners  234  extending through the corresponding apertures and into the end face  258  of the heat sink. When assembled, the end board  260  and end portions of the heat sink and translucent lens portion  252  reside within the receptacle of end cap assembly  214 . 
     Connector system  200  of this first embodiment of the invention comprises additional components that provide for grounding heat sink  254  as an incident of the snap-fit mechanical connectivity described above. In particular, second connector part  220  includes an integrated metal ground strap  238   a  mounted to a side surface thereof. The ground strap  238   a  extends from a base portion of second connector part  220  proximate the support  50  towards the distal leading end of second connector part  220  as shown. Ground strap  238   a  is mounted on the side surface of second connector part  220  that opposes end wall  230  of first end cap assembly  214  when the first connector part  210  and second connector part  220  are in the assembled configuration. Those skilled in the art will recognize a number of available techniques for mounting ground strap  238   a  to second connector part  220 , including the use of mechanical fasteners, adhesives, mounting tabs or slots formed integral with second connector part  220 , or using in laid injection molding techniques or any other available means. Ground strap  238   a  is connected at its proximal end to ground wire  76  via a connection internal to second connector part  220  (not shown). 
     First end cap assembly  214  is shown in  FIG.  10    with a portion cutaway to better illustrate ground plate  232 , which is mounted along the inner surface of end wall  230  of first end cap assembly. Ground plate  232  is of a conductive material, and defines apertures aligned with apertures  236  of end wall  230  for receiving the fasteners  234 . The ground plate  232  may be mounted internal to first end cap assembly  214  by any available means, including by mechanical fasteners, adhesives, mounting tabs or slots formed integral with first end cap assembly, by means of in-laid injection molding techniques, or any other available means. 
     With the first end cap assembly  214  assembled to heat sink  254  as described, ground plate  232  is in electrical contact with the heat sink via the fasteners  234 . At least a portion of ground plate  232  is of a thickness dimension such that when second connector  220  inserts through the opening  216  into the assembled position within first connector  210 , a portion of the exposed conductive surface of ground plate  232  engages an opposing conductive surface of ground strap  238   a.    
     Support  50  is grounded through mechanical connections to the ceiling infrastructure and/or via a connection to an isolated ground wire also providing grounding back to the dedicated ground bus of in input electrical power panel. Ground wire  76  may be connected to the support or to the ceiling infrastructure, or may be wired to a dedicated ground bus, to provide a grounding path for the snap-fit connector system and LED lamp. Thus, heat sink  254  is ground protected by the grounding path provided by the fasteners  234 , ground plate  232 , ground strap  238   a  and ground wire  76 . This snap-fit connector system with integrated grounding electrically grounds the lamp heat sink to the externally grounded lighting fixture or other grounded system as an incident of the first connector  210  and second connector  220  being snap-fit into the fully engaged configuration, thereby eliminating the potentially hazardous condition associated with an ungrounded heat sink. 
     Ground strap  238   a  of the invention may be provided in various shapes, sizes and configurations adapted to establish the desired grounding connection in a wide range of available LED lamp end cap assemblies. In one aspect, ground strap  238   a  may extend further in the horizontal and/or vertical direction than depicted in  FIG.  10    so as to directly engage the support  50  when the second connector part  220  is mounted to the support. In this alternative, the first connector part may form a direct mechanical ground connection with the support  50  without the use of ground wire  76 . 
     Ground plate  232  may also be provided in various different forms other than the circular plate illustrated in the embodiment of  FIG.  10   . For example, ground plate  232  may be provided as a thin conductive clip mounted to the internal surface of end wall  230  and extending generally parallel and opposite ground strap  238   a  of second connector part  220 . The plate may include a portion that protrudes away from end wall  230  and towards the ground strap  238   a  for contacting ground strap  238   a  of second connector part  220 . It will be appreciated from the teachings herein, that various shapes, sizes and geometries of ground strap  238   a  and ground plate  232  can be utilized within the scope of the invention so long as these two components are adapted to come into physical contact with each other when the first connector part  210  and second connector part  220  of connector system  200  are moved into an engaged configuration. 
       FIG.  11    is directed to another embodiment of a ground protecting connector system to further illustrate possible ways of implementing the principles of the invention. The connector system of this embodiment is essentially the same in overall design and functionality as grounded connector system  200  of  FIG.  10    except for the specific configuration of the ground strap. The structure and operation of like components is therefore not repeated. In particular, the ground strap  238   b  of this embodiment is secured at its proximal end to second connector part  220  and has an outwardly protruding profile. It includes a first ramp surface  238   b ′ extending away from the side surface of second connector part  220 , a mid-portion  238   b ″ extending generally parallel to the side surface, and a terminal end portion  238   b ′″ angled back slightly toward the side surface. When the first and second connector parts are in an engaged configuration, mid-portion  238   b ″ engages the inner surface of ground plate  232  to complete a grounding path for the system. Ground strap  238   b  is preferably formed of a thin piece of spring steel having a high yield strength that allows it to be deformed and return to its original shape despite significant deflection. In the engaged configuration, ground plate  232  slightly compresses ground strap  238   b  from its relaxed shape such that its mid-portion  238   b ″ is displaced towards the side surface of first connector part  220 . The resulting spring force biases the mid-portion in the direction of and against the ground plate  232  to maintain secure contact between the mid-portion and the plate. 
     Another embodiment of a grounded connector system in accordance with the principals of the invention can be seen in  FIG.  12   . The connector system of this embodiment is essentially the same in overall design and functionality as grounded connector system  200  of  FIG.  10    except for the specific configuration of the ground strap. The structure and operation of like components is therefore not repeated. In particular, the ground strap  238   c  of this embodiment is provided as a thin wire mesh integrated into the side wall of second connector part  220  by utilizing an in-laid injection molding process. An outer surface of the wire mesh is exposed such that it engages and forms an electrical grounding path with a portion of the inner surface of end plate  232  of first connector part  210  when the connector components are in the engaged configuration. This embodiment may provide manufacturing advantages and results in the second connector part  220  having a thinner profile with no protruding components susceptible to being bent or damaged. 
       FIG.  13    is directed to another embodiment of the grounding system of the invention that can ground protect both the LED tube lamp heat sink and its internal LED emitter board and other internal electronic components. This embodiment is illustrated by reference to a LED tube lamp  350 , which includes multi-sided heat sink  354  with a pair of support walls  359  having a generally V-orientation for supporting multiple LED emitter boards  370  facing different directions. Other components such as an internal driver circuit may also be mounted to the heat sink. The end connector and grounding system of this embodiment may also be adapted to other LED tube lamp forms, including those having a generally circular cross section and a single LED emitter board mounting surface as depicted in  FIGS.  10  to  13   . 
     The connector system  300  of the embodiment of  FIG.  13    includes first connector part  310  formed as part of first end cap assembly  314  and second connector part  320  secured to support  50 . The first end cap assembly  314  consists of a first, cup-shaped receptacle into which the first end of the LED tube lamp body extends. The first end cap assembly  314  is shaped to accommodate the multi-sided heat sink  354 . It comprises side walls  312  extending perpendicular from end wall  330  and forming a receptacle having a generally triangular cross-section. Similar to the embodiments of  FIGS.  10 - 12   , first end cap assembly  314  includes an internal ground plate  332 , which is shown in the cutaway view of  FIG.  13   . The second connector part  320  is of similar design as the connector part  220  described above in connection with the embodiment of  FIG.  10   . It is adapted to extend through an opening in the upper facing side wall of first end cap assembly  314  and form a snap-fit connection to the first connector part by the action of bendable members  322  and live hinges  325  on opposite sides thereof in essentially the same manner described for other embodiments. Second connector part  320  further includes ground strap  338   a  on one side thereof for engaging ground plate  332  of first connector part  310  when the two connector parts are in the engaged configuration. The ground plate  332  is in electrical contact with heat sink  354  through metallic fasteners  334 , which extend through the aligned apertures of end wall  330 , ground plate  332  and end connector board  360  and into corresponding mounting apertures  357  in the end face of the heat sink. Ground strap  338   a  is secured to ground wire  76 . Thus, in essentially the same manner described above in reference to the embodiment of  FIG.  10   , the ground plate  332 , fasteners  334 , ground strap  338   a  and ground wire  76  provide a means to ground protect heat sink  354  when LED tube lamp  350  is installed in the operating state to the support using end connector  300 . 
     The end connector board  360  of this embodiment is a PCB connector board having L-shaped electrical connector components  362 ,  364  thereon that insert into corresponding spaced receptacles in second connector part  320  and cooperate with connector assemblies  72 ,  74  having wires that extend through the second connector part  320  to establish electrical connection between the board  360  and the power supply. The connector components  362 ,  364  may be mechanically and electrically connected to the board  360 , and the board includes traces to provide electrical paths from the connector components to terminals such as terminals  365 . The terminals  365  cooperate with pins  372  extending from LED emitter boards, driver circuit boards or other electrical component to provide power to such components. Thus an electrical path is established between the power supply and the internal componentry of the LED tube lamp  350  when the first and second connector parts of connector  300  are in the engaged configuration. 
     In the embodiment shown, end connector board  360  also includes L-shaped electrical ground pin  366 . Second connector part  320  has a female receptacle  342  adapted to receive the vertically extending portion of the ground pin  366  when the first and second connector parts  310 ,  320  are in the assembled configuration. Receptacle  342  includes an internal connector component (not shown) that forms an electrical path with ground wire  76 , or with a separate ground wire, such that ground pin  366  may function to provide additional ground protection for LED tube lamp  350 . In a preferred aspect, end connector board  360  includes traces electrically connecting ground pin  366  to one of the terminals  365  to provide an isolated grounding path for the internal components of the lamp  350  connected to the terminals  365 . In another aspect, ground pin  366  may also be electrically connected to wire  367  and its loop connector  368 . One of the fasteners  334  may extend through the loop connector  368  to form a ground connection between heat sink  354  and ground pin  366 . This may provide for redundant grounding of the heat sink, or may render the ground strap  338   a  and ground plate  332  unnecessary. Alternatively, ground pin  366  may be electrically connected to the edge of one or more of the screw apertures via internal traces of end connector board  360  and the wire  367  eliminated. The embodiment of  FIG.  13    thus provides multiple options for providing ground fault protection to internal componentry and the heat sink. In a preferred form, ground strap  338   a  and ground plate  332  provide a grounding path for heat sink  354 , and ground pin  366  functions to ground the internal componentry of the LED tube lamp. 
     The ground protected LED lamp connector embodiments described previously provide a ground path for the lamp heat sink and/or internal components at an end of the lamp adapted to receive power from an external power supply. It will be recognized that any of the above embodiments may modified to provide a ground protected snap-fit connector system for the no power end of a single end powered lamp. For example, end connector board  260  of the embodiments of  FIGS.  10 - 12   , and associated connectors and wires, may be eliminated at the no power end with the connector  200  still functioning to provide a ground path for the lamp heat sink in the same manner described above. Connector components  72 ,  74  are also unnecessary at the no power lamp end. Similarly, end connector board  360  may be eliminated to adapt connector  300  of  FIG.  13    for a lamp end that does not receive external power. Alternatively, end connector board  360  may be provided without L-shaped connector components  362 ,  364 , but with ground pin  366  to provide isolated ground protection to the lamp internal components in the manner described. The system is thus highly adaptable to a variety of LED lamp designs and powering options, as may be flexibly implemented to suit the needs of each individual lighting installation. 
       FIG.  14    is directed to an alternative connector system adapted to secure the no power end of a linear LED tube lamp to a light fixture, as well as to provide ground protection to the lamp heat sink. Connector sleeve  600 , which is preferably an injection molded plastic component, is of a form similar to connector sleeve  520  discussed above with reference to  FIG.  9   . A base portion  630  of connector sleeve  600  includes slots  632  on opposite sides thereof into which tabs  52 ,  54  of support  50  slide to secure connector sleeve  600  to support  50 . The base portion  630  extends toward sleeve portion  624  comprising cylindrical sidewall  612  and end wall  610 , which form a cylindrical receptacle  614  sized to receive cylindrical end cap assembly  660  of the no power end of LED lamp  650 . Connector sleeve  600  includes ground plate  620  comprising a conductive material and mounted adjacent the inner surface of end wall  610 . Ground plate  620  is electrically connected to ground wire  680 . The sleeve portion  624  is preferably of a cross-sectional shape selected to match the cross-sectional shape of plastic end cap assembly  660 , which is cylindrical in the illustrated embodiment. Connector sleeves comprising a sleeve portion of other cross-sectional geometries, such as generally triangular, square or rectangular, are also contemplated for use with other lamp designs. 
     LED tube lamp  650  comprises heat sink  654  of a semi-circular cross-section and having a support surface on which LED emitter board  670  is mounted. Translucent lens cover  652  is attached to heat sink  654 . End cap assembly  660  forms a cylindrical receptacle into which and end portion of the heat sink and lens cover inserts. End cap assembly  660  is non-conductive and includes an annular lip  664  circumscribing a recessed mid-portion of the outer surface of the end wall thereof. Ground plate  666  is disposed in the recessed mid-portion and retained by lip  664 . Ground plate  666  is of a conductive material and includes central boss  668  protruding outwardly of its outer surface. End cap assembly  660  is secured to the lamp by means of metallic fasteners  657  extending through apertures  661  of the end wall and ground plate and into mounting apertures  655  and  657  of end face  658  of the heat sink. Ground plate  666  is thus in electrical contact with heat sink  654  through fasteners  657 . 
     In the same manner described above with reference to  FIG.  9   , the no power end LED tube lamp  650  of  FIG.  14    inserts linearly into receptacle opening  614  of connector sleeve  600 . The opposite power input end of lamp  650  is preferably configured with the snap-fit end cap assembly of the type discussed herein to provide for mechanical and electrical connection to a male snap-fit connector mounted to support  50  upon moving the power end upward towards and into engagement with the male snap-fit connector part. With lamp  650  secured to support  50  in its installed configuration, boss  668  is forced into abutting engagement with the exposed conductive surface of ground plate  620 . This engagement completes a grounding path between heat sink  654  and ground wire  680 , which may be grounded to the light fixture or to an external isolated ground connection to provide ground protection to the heat sink. 
     Ground plate  666  may be provided in various shapes, sizes and configurations adapted to establish the desired grounding connection in a wide range of available LED lamp end cap assemblies. It may be provided, for example, as one or more thin conductive straps mounted to the external surface of the end wall of end cap assembly  660  or integrated into the end wall using in-laid molding techniques. Ground plate  620  may also take on other forms besides the circular plate illustrated in the embodiment of  FIG.  14   . For example, ground plate  620  may be provided as a thin conductive clip mounted to the internal surface of end wall  610  and extending generally parallel and opposite ground plate of the end cap assembly  660 . Instead of boss  668  provided on ground plate  666 , a boss may be provided on the ground plate  620  protruding into the receptacle of connector sleeve  600  to provide for contact with a planar form of ground plate  666 . It will be appreciated from the teachings herein, that various shapes, sizes and geometries of ground strap ground plate  666  and ground plate  620  are within the scope of the invention so long as these two components are adapted to come into physical contact with each other when the end cap assembly  660  is seated in connector sleeve  600  and the opposite lamp end secured to the support  50  by a snap-fit connector system of the type described herein. 
     As illustrated in  FIG.  15   , LED tube lamp  650  may be provided with an alternative end cap assembly  690  adapted for use with the same connector sleeve  600  just described. The end cap assembly in this embodiment comprises planar end wall  694  forming on outer end surface of the assembly and cylindrical side wall  692  which extends from the end wall. Ground plate  696  is mounted internal of end wall  694  as shown. Boss  698  of ground plate  696  protrudes through a central opening of end wall  694  as shown. Fasteners  667  extend through apertures  663  in the end wall and ground plate and into apertures  655  and  657  of end face  658  of the heat sink to secure end cap assembly  690  to the lamp. With end cap assembly  690  inserted into connector sleeve  600  to the assembled position, boss  698  abuts the exposed inner conductive surface of ground plate  620 . This completes a ground path from heat sink  654  to ground wire  680  through the fasteners  657 , ground plate  696  and ground plate  620 . 
     The ground protected connector sleeve embodiments of  FIGS.  14  and  15    provide additional options for safely grounding linear LED tube lamps. With the connector sleeve providing ground protection for the heat sink, the configuration of the connector system at opposite power input end may be simplified. In a preferred aspect, the connector sleeve provides a ground path for the heat sink and the snap-fit connector at the opposite power end is adapted to provide isolated grounding of the LED emitter boards and other internal electronic components such as by using a dedicated ground pin as disclosed in  FIG.  13   . This results in a fully grounded lamp having a simplified overall design. 
       FIG.  16    illustrates another embodiment of the grounding system of the invention for ground protecting both the LED tube lamp heat sink and its internal LED emitter board and other internal electronic components. This embodiment illustrates an implementation of the invention in which ground protection is provided through use of a third L-shaped pin associated with the lamp end cap assembly. The body of multi-sided LED tube lamp  350  of this embodiment is substantially similar to the lamp shown in  FIG.  13   , and the description of like components is not repeated. The lamp  350  of  FIG.  16    includes an internal driver board  352  with corresponding pin connector  353  mateable with one of the terminals  365  of end connector board  360 . L-shaped pins  362 ,  364  and  366  are mounted to support board  361  and include stem portions that seat within corresponding mounting apertures of PCB end connector board  360 . Alternatively, the support board  361  may be eliminated and the pins mounded directly to PCB end connector board  360 . 
     The connector system  300  of the embodiment of  FIG.  16    includes first connector part  310  formed as part of first end cap assembly  314  and second connector part  320  secured to support  50 . The first connector part  310  and second connector part  320  function to form a snap-fit mechanical connection in the same way described previously in relation to the  FIG.  13    and other embodiments. The first end cap assembly  314  is essentially the same as that of the embodiment of  FIG.  13    except that ground plate  332  has been eliminated. In this embodiment, the ground strap  228   a  has also been eliminated from the second connector part  320 . 
     The L-shaped electrical connector components  362 ,  364  of this embodiment are in the form of pins having engagement portions that insert into corresponding spaced receptacles  346 ,  344  extending within second connector part  320 . The pins cooperate with connector assemblies  72 ,  74  having wires and corresponding connector terminals that extend through the second connector part  320  to establish electrical connection with the pins and thereby form an electrical path between the lamp internal components and the power supply. The connector components or pins  362 ,  364  are mechanically and electrically connected to the end connector board  360 , and the board includes traces to provide electrical paths from the connector components to terminals such as terminals  365 . The terminals  365  cooperate with pins  372  extending from LED emitter boards and pins  353  extending from the driver circuit board  352  to provide power to those components. Thus an electrical path is established between the power supply and the internal componentry of the LED tube lamp  350  when the first and second connector parts of connector  300  are in the engaged configuration. 
     In the embodiment shown, the heat sink and/or lamp electronic components are ground protected through the third L-shaped connector component  366 , which functions as a dedicated grounding pin. The second connector part  320  has a female receptacle  342  adapted to receive the vertically extending engagement portion of the ground pin  366  when the first and second connector parts  310 ,  320  are in the assembled configuration. Receptacle  342  includes an internal connector component (not shown) that forms an electrical path with ground wire  76  to enable the ground pin  366  to provide ground protection for linear LED lamp  350 . In a preferred aspect, end connector board  360  includes traces electrically connecting ground pin  366  to one of the terminals  365  to provide an isolated grounding path for the internal components of the lamp  350  connected to the terminals  365 . In another aspect, ground pin  366  may also be electrically connected to wire  367 . The wire may be utilized to form a mechanical ground connection to the heat sink or to a pad on driver circuit board  360 . In another aspect, the heat sink may be grounded by means of internal electrical traces in end connector board  360  which connect ground pin  366  to conductive edge portions of one or more screw receiving recesses that engage a corresponding assembly screws  334  when the end cap is assembled to the heat sink. 
     LED lighting products as well as the systems in which they are used are subject to safety and electrical isolation requirements, which are defined in safety standards. Various standards organizations around the world determine individual standards and issue approvals or certificates for equipment and products. Some important standards bodies include Underwriters Laboratories (UL), the American National Standards Institute (ANSI), the International Electrotechnical Commission (IEC), the Canadian Standards Association (CSA) and the Deutsche Elektotechnische Kommission (DKE). The equipment level specifications reference general standards on insulation, such as: IEC60664—Insulation coordination for equipment within low-voltage systems, and UL840—Insulation coordination including clearances and creepage distance for electrical equipment. Besides equipment level specifications there are component level standards. 
     The distance between components that is required to withstand a given voltage is specified in terms of “clearance” and “creepage.” Creepage distance is defined as the shortest path between two conductive materials measured along the surface of an isolator which is in between. Creepage is an important characteristic because reduced creepage will result in the flow of current or “tracking” along the surface of the insulation. Tracking causes localized heating and carbonization of the surface, and may lead to failure of the insulation. The Comparative Tracking Index (CTI) is used to measure the electrical breakdown (tracking) properties of an insulating material. Creepage also depends on contamination of the surface, humidity, corrosive chemicals and the altitude in which the equipment is installed. Clearance distance describes the shortest distance between two conductive materials measured through air. Sufficient clearance distance prevents an ionization of the air gap and a subsequent flashover. Similar to creepage distance, the pollution degree, temperature and relative humidity influence the tendency for a breakdown. 
       FIG.  16    illustrates a preferred arrangement of the electrical connector components  362 ,  364  and the ground electrical connector component  366  to satisfy the spacing distance between electrical conductors required for a wide range of voltage levels, as well as to assure that the system is grounded before external power is applied. Ground pin  366  is shown mounted at a laterally centered position, and the power electrical connector components  362 ,  364  are mounted on opposite sides of the board&#39;s lateral midline and spaced approximately equally therefrom. Ground pin  366  attaches to support board  361 , and to end connector board  360 , at a position vertically offset from the connector components  362 ,  364 , and the tip of its vertically extending engagement portion protrudes above the tip of the vertically extending engagement portions of connector components  362 ,  364  in the vertical direction. The internal connector components preferably extend approximately the same distance within second connector part  320  so that their ends are generally aligned at a position adjacent the leading end face thereof, and preferably at a position recessed from the leading end face. As first end cap assembly  314  is moved upward into an engaged configuration and the pins insert into the corresponding receptacles of second connector part  320 , ground pin  366  will engage its corresponding internal connector component to form an electrical ground circuit for the linear LED lamp before the connector components  362 ,  364  engage their corresponding connector components of second connector part  320 . This enhances overall safety by assuring the system is grounded before power is applied to the linear LED lamp. This is illustrated further in relation to the embodiment illustrated in  FIGS.  17  to  21   , and in particular  FIGS.  19   a  and  19   b    and the corresponding discussion below. 
     The horizontal leg portions of L-shaped electrical connector components  362 ,  364  shown in  FIG.  16    extend further in the longitudinal direction of the linear LED lamp  350  than the horizontal leg portion of ground electrical connector component  366 . The illustrated positioning and configuration of the connector components  362 ,  364  and  366  provides increased creepage distance between these components, allowing the connector system to satisfy creepage requirements over a wide range of voltage operations. This is explained more fully in relation to the embodiment of  FIGS.  17  to  21   , which illustrates a similar connector system for a generally cylindrical linear LED lamp. 
     The linear LED lamp and connector system illustrated in  FIGS.  17  to  21    is similar to the embodiments described  FIGS.  10  to  12    but utilizes a third ground pin instead of an end cap ground plate and external strap system for providing ground protection to the lamp heat sink and internal components. LED tube lamp  750  comprises an elongate tubular body portion including a metallic heat sink  754  extending throughout a generally upward facing portion of the circumference of the tubular body, and a transparent or translucent lens portion  752  extending throughout a generally downward facing portion of the circumference of the tubular body. The heat sink is preferably formed of an aluminum alloy, although other thermally conductive materials may be used. At least one LED emitter panel  770  comprising a printed circuit board mounting a series of LEDs is mounted to the heat sink internal to the tubular body. The heat sink may include fins  755  extending along its length to increase the effective surface area for transfer of heat to the atmosphere. The LED lamp  750  may include an internal ballast or driver module (not shown) or may alternatively utilize an external ballast associated with the lighting fixture. Heat sink  754  has a generally semi-circular cross-section in a plane perpendicular to the length of the lamp, with support wall  759  extending across the internal region thereof to provide a mounting surface for LED emitter panel  770 . Other heat sink geometries are also contemplated, including, for example, a configuration such as the one illustrated in  FIG.  16    comprising multiple support walls arranged in a generally V-shape and lying in intersecting planes for supporting multiple LED emitter panels arranged to distribute light over a wide area. 
     With further reference to  FIG.  17   , LED lamp  750  is mounted at its first end to a support of a lighting fixture (not shown) by means of snap-fit connector system comprising first connector part  710  and second connector part  720  configured to mount to the support. The second connector part  720  can be press connected to tabs of the support by means of oppositely opening slots formed between flanges  724  and flanges  723  extending outwardly from opposite sidewalls of second connector part  720 . Of course other releasable, and potentially permanent, connections are contemplated. 
     As is further illustrated in  FIGS.  19   a  and  19   b   , the second connector part  720  has a pair of bendable parts  722  on opposite sides thereof, each operable through hinge  725 , which are engaged by the edge of the opening  716  and progressively cammed from a holding position towards an assembly position as the first connector part  710  is moved up to and into the engaged position. The first bendable parts  722  move from the assembly position back towards the holding position with the first part realizing, the engaged position. The wall  714  resides captively between surfaces of the first connector part  710  in the engaged position to maintain this snap-fit connection. A pair of actuators  721  on opposite sides of second connector part  720  can be pressed to move the first bendable parts  722  towards its assembly position to allow them to pass through the opening  716  so that first connector part  710  can be separated from the second connector part  720 . Second connector part  720  includes a curved concave ledge portion  732  at the juncture of sidewall  730  and sidewall  740  and has a generally planar opposite outer sidewall. This permits the second connector part  720  to insert further into the interior of first connector part  710 , with a portion of the convexly curved outer wall portion of first connector part  710  seating within the curved ledge portion  732 . 
     Heat sink  754  has a planar end face  758  at a first end thereof defining a pair of apertures  757 . Connector end board  760  includes a pair of corresponding notches  753  aligned with heat sink apertures  757 . The end wall of first end cap assembly  714  defines corresponding aligned apertures  736 . The end cap assembly  714  and connector board  760  may be secured to heat sink  754  at the first end of LED tube lamp  750  with a pair of metallic fasteners (not shown) extending through the corresponding apertures and into the end face  758  of the heat sink. When assembled, the end board  760  and end portions of the heat sink and translucent lens portion  752  reside within the receptacle of end cap assembly  714 . 
     As  FIG.  17    illustrates, the receptacle of end cap assembly  714  may receive end connector board  760  having L-shaped electrical connector components  762 ,  764  and  763  thereon that cooperate with connector assemblies  72 ,  74  and  76  of second connector part  720 . The connector assemblies have wires terminated with conductive cylindrical terminals  72   a ,  74   a  and  76   a  respectively that extend into the receptacles of second connector part  720 . The wires of assemblies  72  and  74  connect to a power supply and the third wire  76  provides an isolated ground circuit. The connector components  762  and  764  may connect to LED emitter board  770  by means of wires  766  and may similarly provide power to other internal components of linear LED lamp  750 . In one aspect, wires  766  connect to an internally mounted driver to provide AC line voltage which the driver converts to DC voltage supplied to the LED emitter board and optionally other internal componentry. The ground connector  763  may connect via wire  767  to the heat sink or to an internal driver board. 
     The L-shaped electrical connector components  762 ,  764  and  763  on the connector board  760  each have a first portion extending horizontally in direction generally parallel to the length of the body and a second engagement portion extending vertically in a direction traverse to the length of the body and towards the second connector part  720  when said first connector part  710  is moved towards the second connector part and into the engaged position. The vertically extending engagement portions insert into corresponding spaced receptacles  744 ,  746  and  742  respectively in the leading end of second connector part  720  and engage the connector terminals  74   a ,  72   a  and  76   a  respectively that extend within the second connector part  720  to establish electrical connections with the power supply and a grounding circuit.  FIG.  18    provides a perspective view showing the interaction of the components in the fully engaged configuration. 
     Although the embodiment illustrated in  FIG.  17    utilizes internal wire connections, the connector board  760  may alternatively be in the form of a printed circuit board (PCB) connector containing male or female electrical terminals for connecting to corresponding terminals associated with LED emitter board  770 , a driver circuit or other internal components of the lamp to provide a no-wire design. In both approaches, connector components  762 ,  764  provide an electrical path over which electrical power from a power supply is provided to the LED emitter board  770  and optionally other internal components, and the connector component  763  provides a grounding circuit. 
     The configuration of the L-shaped connectors shown in  FIG.  17    is similar to that of the configuration shown in embodiment of  FIG.  16   . The advantages of this configuration in relation to satisfying spacing distance requirements between electrical conductors and other standards requirements is further explained by reference to  FIGS.  19   a ,  19   b ,  20   a ,  20   b ,  21   a    and  21   b.    
       FIG.  19   a    shows that ground connector component or pin  763  is mounted at a laterally centered position, and the power electrical connector components  762 ,  764  are mounted on opposite sides of the vertical diameter of support board  760  and spaced approximately equally therefrom. Ground pin  763  attaches to support board  760  at a position vertically offset from the connector components  762 ,  764 , and the tip of its vertically extending leg protrudes above the tip of the vertically extending legs of connector components  762 ,  764  in the vertical direction. The internal connector terminals  72   a ,  74   a  and  76   a  extend approximately the same distance within second connector part  720  to positions offset from the leading end face thereof by the dimension shown as D3. As first end cap assembly  714  is moved upward into an engaged configuration and the pins insert into the corresponding receptacles of second connector part  720 , ground pin  763  will engage its corresponding internal connector component to form an electrical ground circuit for the linear LED lamp before the connector components  762 ,  764  engage their corresponding connector components of second connector part  720 , as shown in  FIG.  19     a.    
       FIG.  19   b    shows the relative positioning of the components with the first connector part  710  and second connector part  720  in the engaged position. In this embodiment, second connector part  720  is configured so that its leading end extends internally approximately one-half of the vertical diameter of end cap assembly  714  in the view shown. The vertical portions of connector components  762 ,  764  and  763  are of sufficient length so that they insert into the cylindrical terminals  74   a ,  72   a  and  76   a  respectively in the engaged position. The connector components may have a predetermined length selected to meet a minimum desired distance over which the connector components engage the terminals. For example, the vertical portions of connector components  762  and  764  extend the distance D4 from the centerline of the end cap assembly, and the pin engagement distance when the components are assembled is represented by D4 minus D3. In a preferred embodiment, the pins are configured to provide a pin engagement distance of at least 4.0 mm, and more preferably at least 4.3 mm. 
       FIG.  20   a    is end view of the second connector part  720  showing the arrangement of receptacles  744 ,  746  and  742  accessible through openings in the end face of the leading end thereof. The connector terminals  74   a ,  72   a  and  76   a  housed within the receptacles are also shown. The shortest distance between adjacent conductors along the surface of the end face is the distance from the outer edge of receptacle openings  742  and  744 , which is labeled as D1. This dimension is preferably at least about 2.0 mm to provide adequate electrical isolation at higher voltage operation. The outer edges of receptacle openings  746  and  744  for the power terminals are preferably spaced by at least 2.8 mm. As shown in the side view of  FIG.  20   b   , the distance from the end of the terminals to the end face of second end connector  720  is D3. This dimension is preferably at least about 5.5 nm to provide adequate electrical isolation at higher voltage operation. Accordingly, the shortest path between two adjacent connector terminals measured along the surface of the isolator between them is the sum of D3 and D1 and D3. In a preferred form, second connector part  720  may be dimensioned such that this creepage distance is at least about 13.0 mm. 
       FIG.  21   a    shows a view of end cap assembly  714  from above, looking into opening  716 . The clearance distance separated by air between any portion of adjacent connector components is preferably at least 3.0 mm, and more preferably at 3.2 mm to provide for safe operation at voltage levels up to 600 volts. The shortest distance separated by air between vertical legs of adjacent connector components is the distance between the vertical engagement portion of ground connector component  763  and the vertical engagement portion of either of the power connector components  762  and  764 , which is designated D2 in  FIG.  21   a   . This distance is preferably controlled to provide minimum clearance of at least 3.5 mm. 
     The ground protected connector systems disclosed herein provide safe and reliable means for securing linear LED tube lamps to a lighting fixture. The disclosed ground protected systems alleviate all safety concerns, permit high power operation, provide for flexible lamp design and installation options, and can be implemented in a cost-effective manner. 
     In a preferred aspect, the linear lamp  750  illustrated in  FIGS.  17  to  21    connects to the support  50  of the lighting fixture by means of a similar second snap-fit connector system at its opposite end. The second snap-fit connector system need not include electrical connector terminals and may be provided without a means for connecting to the power supply. The opening  716  in first connector part  710  is preferably slightly larger than the corresponding dimensions of the leading end of connector  720 , and the same relative sizing is preferable for the end cap assembly and support connector at the opposite lamp end. Sufficient clearance between the end cap openings and the leading end of the support connectors permits lamp  750  to be shifted slightly relative to the support connectors along the direction of its length or transverse to its length so that the vertical extending portions of connector components  764 ,  762  and  763  can be readily aligned with and inserted into receptacles  744 ,  746  and  742  during lamp installation. 
       FIG.  22    shows an alternative approach in which the opposite end of lamp  750  is connected to the fixture support by means of the cylindrical connector sleeve  520  shown previously in  FIG.  9   . The above description of connector sleeve  520  and its advantages is not repeated. The use of connector sleeve  520  may provide for easier installation, as discussed above. It also accommodates small variations in lamp length by permitting the lamp to be shifted linearly during installation so that connector components  764 ,  762  and  763  align with and inserted into receptacles  744 ,  746  and  742 . Of course, connector sleeves comprising a sleeve portion of other cross-sectional geometries, such as generally triangular, square or rectangular, are also contemplated for use with other lamps having corresponding end cap cross-sectional geometries. 
     Those skilled in the art will recognize that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the spirit and scope of the invention, and that such modifications, alterations, and combinations, are to be viewed as being within the scope of the invention.