Patent Publication Number: US-2022221135-A1

Title: Flame protected optic

Description:
The present application claims the benefit of priority of U.S. Provisional Patent Application Ser. No. 63/136,367, titled “Flame Protected Optic,” filed Jan. 12, 2021, which is incorporated herein by reference. 
    
    
     BACKGROUND 
     The application relates to luminaires and components for luminaires. 
     Light fixtures, or luminaires, include electric light sources and provide an aesthetic and functional housing in both interior and exterior applications. Sometimes, where luminaires are used in environments containing flammable gas, legal regulations sometime require luminaires to qualify for safe use in such an environment. Qualification for safe use of the luminaire enclosure in an environment containing flammable gas may include a requirement that any flame resulting from ignition of flammable gas in the luminaire is encapsulated by the luminaire and prevented from reaching the exterior of the luminaire. That is, the requirement may be that the luminaire be flame encapsulating in that it is configured to encapsulate any flames originating within the luminaire. 
     SUMMARY 
     According to an exemplary embodiment, a luminaire includes a flame encapsulating luminaire enclosure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional side view of a luminaire comprising a luminaire enclosure. 
         FIG. 2  is a front view of a luminaire comprising a luminaire enclosure. 
         FIG. 3  is a view of a pcb board, LED array, and LED protective lens array configuration including flame path gaps. 
         FIG. 3 a    is a top view of an LED protective lens array. 
         FIG. 3 b    is a side view of an LED protective lens array. 
         FIG. 3 c    is an underside view of an LED protective lens array including flame path gaps. 
         FIG. 4  is a detailed view of a luminaire lens securing structure of a luminaire enclosure cover. 
         FIG. 5 a    is a top view of an LED protective lens array. 
         FIG. 5 b    is an underside view of an LED protective lens array including flame path gaps. 
         FIG. 5 c    is a side view of an LED protective lens array. 
         FIG. 5 d    is a detailed view of a LED protective lens design. 
         FIG. 6 a    is a perspective view of a luminaire comprising a flame encapsulating luminaire enclosure. 
         FIG. 6 b    is a top view of a luminaire comprising a flame encapsulating luminaire enclosure. 
         FIG. 6 c    is a sectional side view of a luminaire comprising a flame encapsulating luminaire enclosure. 
         FIG. 7 a    is a perspective view of a luminaire comprising a flame encapsulating luminaire enclosure. 
         FIG. 7 b    is a top view of a luminaire comprising a flame encapsulating luminaire enclosure. 
         FIG. 7 c    is a sectional side view of a luminaire comprising a flame encapsulating luminaire enclosure. 
         FIG. 8 a    is a perspective view of an LED protective lens array clamp plate. 
         FIG. 8 b    is a perspective view of an LED protective lens array clamp plate. 
         FIG. 9 a    is a top view of a standalone battery indicator light lens. 
         FIG. 9 b    is a sectional side view of a standalone battery indicator light lens. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments are explained in detail, it is to be understood that embodiments described and illustrated are not limited in their application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The embodiments described and illustrated may be practiced or carried out in various ways and other embodiments are possible. 
     Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. As used within this document, the word “or” may mean inclusive or. As a non-limiting example, if it were stated in this document that “item Z may comprise element A or B,” this may be interpreted to disclose an item Z comprising only element A, an item Z comprising only element B, as well as an item Z comprising elements A and B. 
     Various embodiments described herein are directed to luminaire components that prevent flame transmission from the inside of a luminaire to the outside of a luminaire. In certain aspects, the luminaire can be used in an environment containing flammable gas, for example, in specialized lab work, testing applications, or workspaces containing flammable gas. The luminaire may comprise a luminaire enclosure and include light emitter(s) configured to emit light directly through a luminaire enclosure lens. This application discusses components that can be used to prevent flame transmission from the inside of a luminaire to the outside of a luminaire, while allowing one or more light emitters of the luminaire to transmit light from the interior of the luminaire to the exterior of the luminaire thereby creating a flame encapsulating luminaire. A configuration of the luminaire light emitters and light emitter protective lenses may be accomplished so that a lightweight, slim luminaire enclosure that prevents transmission of an internal flame to the exterior of the luminaire can be accomplished while still facilitating a transmission of light from the interior of the luminaire enclosure to the exterior of the luminaire enclosure. Accordingly, the components and assemblies described herein can be safely integrated with systems that operate in the presence flammable gas. 
       FIG. 1  illustrates a sectional side view of a redundantly flame encapsulating luminaire system  10   o  comprising a luminaire enclosure  102  including a luminaire enclosure backing  104  and a luminaire enclosure cover  106 . The luminaire enclosure backing  104  and luminaire enclosure cover  106  are secured together in a manner that encapsulates any flame that may ignite within the luminaire enclosure  102  and thereby prevents any such flame from escaping the luminaire enclosure  102  at any point at which the luminaire enclosure backing  104  and luminaire enclosure cover  106  meet. Moreover, the luminaire enclosure  102 , when assembled, is capable of fully encapsulating any flame that may ignite within the luminaire enclosure  102  according to a protective standard for enclosures. For example, the flame encapsulating protective standard of the luminaire enclosure  102  may be the Ex d standard. 
     In the embodiment shown, an encapsulating gasket  108  is disposed between the luminaire enclosure backing  104  and the luminaire enclosure cover  106 , thereby further ensuring that no flame is transmitted from the inside of the luminaire enclosure  102  to the outside of the luminaire enclosure  102 . The luminaire enclosure cover  106  includes a lens accommodating window  114  having at least an outer bezel lip  116 . In the embodiment shown, the luminaire lens  112  is cemented into place within a lens accommodating window  114  of the luminaire enclosure cover  106 , against the outer bezel lip  116 , by a sealing agent  118 . The sealing agent may be a silicone sealant adhesive but may include other sealing agents. A flame protected luminaire lens  112 , disposed in the luminaire enclosure  102 , allows light to be transmitted from the inside of the luminaire enclosure  102  to the outside of the luminaire enclosure  102  while also maintains the flame encapsulating protective standard of the luminaire enclosure  102 . 
     In the embodiment shown, the plurality of LED arrays  120  is arranged on a pcb board  122 . A plurality of LED protective lens arrays  124  are secured to the luminaire enclosure backing  104 , through the pcb board  122 . The LED protective lens arrays  124  are positioned over each of the LED arrays  120  and secured to the pcb board  122 . The luminaire lens  112  is positioned at a distance from the LED protective lens arrays  124  and pcb board  122 . In the embodiments shown, a spacer portion  127  of the assembled luminaire enclosure  102  defines a luminaire cavity  128  between the LED protective lens arrays  124  and the luminaire lens  112  by mechanically preventing the movement of the luminaire lens  112  and the pcb board  122  toward one another within the luminaire enclosure  102 . When fabricating the luminaire enclosure  102 , the volume of the luminaire cavity  128  may be strategically determined based on a particular flame encapsulating protective standard. For example, if the Ex d protection standard is applied, the volume of the luminaire cavity  128  is minimized when fabricating the luminaire enclosure  102 . For example, to adhere to a particular flame encapsulating standard, the dimensions of the luminaire enclosure cover and the luminaire enclosure backing may be chosen so that the height of the luminaire cavity (i.e., the distance between the luminaire lens and the luminaire enclosure backing) is between 5 mm and 100 mm. Minimizing the volume of the luminaire cavity  128  while adhering to flame path and gap requirements imposed by the relevant flame encapsulating standard helps to reduce the required reference pressure that the luminaire enclosure  102  must withstand during an overpressure test—for example, under the Ex d protection standard, in particular. In the embodiment shown, the LED protective lens arrays  124  mitigates the transmission of flames resulting from the ignition of flammable gas under the LED protective lens arrays  124  while the luminaire lens  112  may be configured to prevent transmission, to the exterior of the luminaire enclosure  102 , of any flame resulting from ignition of within the luminaire enclosure  102 . Additionally, a LED protective lens array clamp plate  111  is positioned over the LED protective lens arrays and fastened to the luminaire enclosure backing by a mechanical fastener  126 , thereby clamping the LED protective lens arrays  124  to the pcb board  122 . The LED protective lens array clamp plate  111  may be rigid or flexible, and made of metal, ceramic, plastic, or any other heat resistant or flame-resistant material. The LED protective lens array clamp plate  111  secures the LED protective lens arrays  124  to the pcb board  122  so that no flames ignited under the LED protective lens array have breathing room to travel from under the LED protective lens array into the luminaire cavity  128 . Therefore, in some embodiments, the entire luminaire enclosure  102  does not necessarily need to meet the relevant protective standard. That is, in some embodiments, only the LED protective lens arrays  124 , pcb board  122  and LED protective lens array clamp plate  111 , in combination, need to meet the relevant protective standard (e.g., Flame encapsulation, Ex d protection, Ex e protection, etc.). 
     In the embodiment shown, the luminaire enclosure backing  104  comprises a heat conductive material and acts as a heatsink for the pcb board  122 . The luminaire enclosure backing  104  acts as a mounting surface for the pcb board  122  and may conduct heat to the luminaire enclosure backing  104  via the mechanical fasteners (not shown) or via surface contacts or heat pipes. In some embodiments, the entire luminaire enclosure  102  may be comprised of a lightweight, heat-conductive metal such as aluminum or titanium. In this way, the entire luminaire enclosure may be used as a heatsink for the LED arrays  120  and the pcb board  122  during operation of the luminaire system  100 . In some embodiments, only certain parts, such as limited portions of the luminaire enclosure backing  104  and luminaire enclosure cover  106  comprise a heat-conductive material. In such embodiments, those certain parts may be used as localized heatsinks. A standalone heatsink  150  can be positioned in or on the luminaire enclosure  102  and draw heat from the LED arrays  120  during operation. However, in most cases, the luminaire enclosure  102  is constructed of a heatsinking material such as a heat conductive metal, and the luminaire enclosure  102 , itself, may therefore act as a heatsink for the LED arrays  120  during operation. 
     In the embodiment shown, the luminaire system  100  includes a controls enclosure  132  that encloses a lighting gearbox  134  and an LED driver  136 . Here, the controls enclosure  132  is also qualified to encapsulate flames ignited within the controls enclosure  132 . That is, the controls enclosure  132  comprises a controls enclosure backing  138  and controls enclosure cover  139  that, when secured together, yield a seal or flame path that will prevent flames inside the controls enclosure  132  from reaching the outside of the controls enclosure  132  (e.g., Ex d protection qualified). In the embodiment shown, the controls enclosure  132  removably connects to the luminaire enclosure  102  via an adaptor  140 . In some embodiments, the adaptor  140  connects the controls enclosure  132  to the luminaire enclosure  102  via electrical contacts. In other embodiments, the adaptor  140  connects the controls enclosure  132  to the luminaire enclosure  102  wirelessly. In still other embodiments, the adaptor  140  connects the controls enclosure  132  to the luminaire enclosure  102  via a removable or fixed wired connection. 
     In the embodiment shown, the lighting gearbox  134  is configured to perform analog regulation of an electrical input from a power source (not shown) and output a regulated electrical signal to the LED driver  136 . The LED driver  136  may deliver an electrical signal to the LED arrays  120  based upon the regulated electrical signal received from the lighting gearbox  134 , causing the LED arrays  120  to emit light. 
     One or more mounting components  142  may be disposed on one or more portions of the luminaire enclosure  102 . The mounting components  142  are configured to secure the luminaire enclosure  102  to a rod, a cord, a chain, or any other known component or assembly for attaching a luminaire to a surface or hanging it therefrom. The mounting components  142  can also be configured to connect the luminaire enclosure  102  to a pole, post, ceiling, or other structure. Mounting components  142  may also include brackets having a pair of openings that receive fasteners to fasten the luminaire enclosure  102  to a wall. Similar mounting components can also be used to secure the controls enclosure  132  to a surface. 
     The LED driver  136  may be disposed in the luminaire enclosure  102 , when present, or in the controls enclosure  132 , when present. The, lighting gearbox  134  may be disposed in the luminaire enclosure  102  or in the controls enclosure  132 , similarly. A power supply  146  may provide power to the luminaire enclosure  102  or controls enclosure  132  and in turn the pcb board  122 , the LED driver  136  and the LED arrays  120 . An LED driver  136  provides a power signal to the LED arrays  120 , causing them to emit light. The power supply  146  may be any combination of drivers, ballasts, or other power supply depending on the type of LEDs in the LED arrays  120 . The LED driver  136  may be a separate component or may be integrated with a light engine on the same circuit board as the LED arrays  120 . For example, the power supply  146  may be a power signal corrector including components such as a voltage regulator or bridge rectifier. Additionally, the power supply  146  may be an onboard or externally connected battery. In certain aspects, the luminaire enclosure may be connected to power supply  146  or connected directly to line power (not shown). 
     One or more control components  148 , may be connected to or integrated with the luminaire system  100 . The control components  148  can include backup battery units, fuses, microprocessors, FPGAs, surge protectors, wired or wireless communication modules (e.g., CAT5, radio, Wi-Fi, etc.), sensors (e.g., light, occupancy, motion, heat, temperature, etc.), or any combination thereof. In some embodiments, the control components  148  include components facilitating the connection of the luminaire system  100  to a network that includes luminaire controllers, or one or more controllers for distributed communication and centralized control of the luminaire system  100 . 
     Certain embodiments utilize reflectors, baffles, louvers or other optical features to direct light through the luminaire lens  112  during operation of the luminaire system  100 .  FIG. 1  shows an embodiment of a luminaire system  100  illustrated as a linear luminaire. In many embodiments, LED arrays  120  are positioned in the luminaire enclosure  102  and configured to emit visible light directly through the luminaire lens  112 . However, in other embodiments, reflectors, louvers, fiber optics, or baffles may be used to transmit light emitted by the LED arrays  120  through the luminaire lens  112  indirectly. 
     In some embodiments, a luminaire enclosure cover  106  secures the luminaire lens  112  to the luminaire enclosure backing  104 , by sandwiching the luminaire lens  112  between the luminaire enclosure cover  106  and luminaire enclosure backing  104  or an extension of either (e.g.,  116 ) when the luminaire enclosure  102  is tightened closed by enclosure fasteners (not shown). In other embodiments, the luminaire lens  112  is not sandwiched between the luminaire enclosure backing  104  and the luminaire enclosure cover  106  when the enclosure is sealed by enclosure fasteners. Additionally, in some embodiments, the sealing agent cementing the luminaire lens  112  in or to the luminaire enclosure cover  106  can be replaced by mechanical fasteners, welds, etc. Similarly, in some embodiments, mechanical fasteners and enclosure fasteners may be replaced by adhesives, welds, etc. In other embodiments, the lens accommodating window  114  also includes an inner bezel lip (not shown). In such embodiments, the luminaire lens  112  may be retained between the outer bezel lip  116  and the inner bezel lip of the lens accommodating window  114 . In most embodiments, the luminaire lens  112  is generally planar in shape, but it is contemplated that the luminaire lens  112  may take other shapes and that other configurations may be used, and that the combination of the means of securing the luminaire lens  112 , may still be qualified for use in environments containing flammable gases or under a flame encapsulating protective standard. Additionally, the luminaire lens  112  can be plain or it can have optical features (e.g., frosting, textured surface, prisms, etc.) that alter or condition light emitted from a visible light emitter, such as a plurality of LED arrays  120 . The luminaire lens  112  can also be used to address color mixing or color angle concerns. 
     In a number of embodiments, the encapsulating gasket  108  may not aid in encapsulating a flame and in some embodiments may not be present. For example, in some embodiments, the encapsulating gasket may be configured primarily to prevent the ingress of dust or liquid into the luminaire enclosure  102 . As yet another example, in an embodiment including the luminaire enclosure  102 , the encapsulating gasket  108  may be excluded from the luminaire enclosure  102  because, for a particular use of the luminaire system  100 , there may be no need to prevent the ingress of dust or liquid into the luminaire enclosure  102 . 
     In a number of embodiments, LED arrays  120  are not disposed in a redundantly flame-encapsulating luminaire system  100 . In such cases, the LED arrays  120  may be sufficiently flame protected by the use of LED protective lens arrays  124 . In some cases, LED protective lens arrays  124  may be secured to pcb board  122  over LED arrays  120 . luminaire enclosure  102  may be entirely absent in such an embodiment, and LED protective lens array clamp plate  111  may be used in concert with LED protective lens arrays  124  to perform sufficient flame encapsulation to provide a flame-encapsulating luminaire system  10  without the use of luminaire enclosure  102 . As another example, in embodiments lacking a luminaire enclosure  102 , the encapsulating gasket  108  is not used in conjunction with the luminaire system  100 . It is also contemplated herein that a single LED protective lens may be used, independent from an LED protective lens array  122 , to provide flame encapsulation for a single LED or light emitter, with or without a luminaire enclosure  102 , by using the approaches taught herein. 
       FIG. 2  illustrates a front view of the luminaire system  200  including a luminaire enclosure  202 . Enclosure fasteners  230  are positioned along the perimeter edge of the luminaire enclosure cover  206 . The even spacing of enclosure fasteners  230  may help ensure a flame-tight seal of the luminaire enclosure cover  106  against the luminaire enclosure backing  104 , when such a flame-tight seal is desired. Similarly controls enclosure fasteners  230  are positioned at the corners of the controls enclosure  232  and may likewise ensure a flame-tight seal between the controls enclosure backing  138  and the controls enclosure cover  239 , when desired. Additionally, mechanical fasteners  226  sandwich the pcb board  122  between the LED protective lens array clamp plate  211  and the luminaire enclosure backing  104 . In the embodiment shown, a plurality of LED arrays  220 , is clearly visible, and configured to emit light directly through the luminaire lens  212 , when powered. Additionally, adaptors  240   a ,  240   b  ensure redundant, direct communication between the luminaire enclosure  202  and the controls enclosure  232 . 
       FIG. 3  illustrates a closeup view of the LED arrays  320  within of the luminaire system  200  is shown. In the embodiment shown, the LED protective lens arrays  324  are tightly secured in over individual LED elements  323  of the LED arrays  32   o , by mechanical fasteners  226 ,  326 , thereby creating a mechanical seal that disallows a flame from travelling into or out of any of the protective lenses  352 , within the LED protective lens arrays  324 . In some embodiments, the LED protective lens arrays  324  are cemented into place a by an LED protective lens array sealing agent (not shown) that aids in making each of the protective lenses  352 , flame encapsulating. For example, the sealing agent may be a silicone sealant adhesive, but may include other sealing agents. In some embodiments, a flame-tight LED protective lens array gasket (not shown) may be used in conjunction with the LED protective lens arrays  324 . In such cases, the LED protective lens arrays  324 , may be pressed down onto the LED protective lens array flame-tight gasket, thereby creating the aforementioned flame-tight seal. LED protective lens array clamp plate  311  protects this arrangement and further ensures a flame-tight seal between the LED protective lens arrays  324 , and the pcb board  222 . This flame-tight seal is indirectly exhibited by flame path  354 , shown in  FIG. 3 c    on the underside of one of LED protective lens arrays  324 . Further, the LED protective lens array clamp plate  311 , protects the LED protective lens arrays  324  from deformation or movement during the ignition of any flammable gas within the luminaire enclosure  102 ,  202 , or under the LED protective lens arrays  324 . 
     As shown in  FIGS. 3 a , 3 b , and 3 c   , the LED protective lens array  324  includes eight LED protective lenses  356  in a 2×2 configuration. Each LED protective lens  356  includes an LED accommodating cavity  358 . The LED protective lens array  324  also includes a center aperture  360  configured to receive the mechanical fastener  226 . The LED protective lens array  324  also includes, at its corners, fastener accommodating cutouts  362 . The LED protective lens array  324  is configured to be attached to the pcb board  222  by way of mechanical fasteners  126  interacting with the pcb board  222  via at least one of the center aperture  360  and the fastener accommodating cutouts  362 . The LED accommodating cavities are  358  are configured to overlay and protect the individual LED elements  323  of the LED arrays  120  when the LED protective lens array  324  is placed onto the pcb board  222 . 
       FIG. 4  illustrates a luminaire enclosure cover  406  including an encapsulating gasket  408  a luminaire lens  412  and one of enclosure fasteners  430 . The luminaire enclosure cover  406  may be configured to ensure that the luminaire enclosure  202  is flame encapsulating when secured to the luminaire enclosure backing  104  according to the methods and products described herein. For example, in the embodiment shown, the sealing agent  418  cements the luminaire lens  412  into the lens accommodating window  214  of the luminaire enclosure cover  406 . The sealing agent  418  may be flame-tight, and thereby create a flame-tight seal between the luminaire lens  112 ,  412  and the luminaire enclosure cover  406  that disallows flames from exiting the luminaire enclosure  202  between the luminaire lens  112 ,  412  and the luminaire enclosure cover  406 . Similarly, in some embodiments, an encapsulating gasket  408  is flame-tight. In embodiments wherein the luminaire enclosure cover  106  is flame-tight, and the luminaire enclosure cover  106  is flame-tight and comprises an encapsulating gasket  408  the entire luminaire enclosure  202  becomes flame encapsulating when fastened together by the enclosure fasteners  430 . 
       FIGS. 5 a , 5 b , and 5 c    illustrate a LED protective lens array  524  including four LED protective lenses  556  in a 2×2 configuration. Each LED protective lens  556  includes an LED accommodating cavity  558 . the LED protective lens array  524 , and includes a center aperture  560  configured to receive the mechanical fastener  226 . The LED protective lens array  524  also includes, at its corners, fastener accommodating cutouts  562  configured to be engaged by a mechanical fastener  126 . The LED protective lens array  524  is configured to be attached to the pcb board  222  by way of mechanical fasteners  126  interacting with the pcb board  222  via at least one of the center aperture  560  and the fastener accommodating cutouts  562 . The LED accommodating cavities are  558  are configured to overlay and protect the individual LED elements  323  of the LED arrays  120  when the LED protective lens array  524  is placed onto the pcb board  222 . 
       FIG. 5 d    illustrates a cross-section  562  of an embodiment of the led protective lens  556 . In the embodiment shown, the LED accommodating cavity  558  includes plurality of inner walls  564  forming tiered, concentric, conical cavities of differing slopes, diameters, and heights. In the embodiment shown, the outermost wall of the plurality of inner walls  564  has a diameter of 6.7 millimeters and a height of 0.84 millimeters; a second wall, just above the outermost wall, has a diameter of 6.37 millimeters and rises 0.64 millimeters above the outermost wall; a third wall, just above the second wall has a diameter of 3.97 millimeters and rises 1 millimeter above the second wall; lastly, a final wall, just above the third wall, rises 0.21 millimeters above the third wall, has a diameter of 2.06 millimeters, and comes to a closed, conical apex in the center of the LED accommodating cavity  558 . 
       FIGS. 6 a  and 6 b    illustrate a perspective view and a top view, respectively, of the luminaire system  600  including a luminaire enclosure  602 . Enclosure fasteners  630  (screws, in the embodiment shown) are positioned along the perimeter edge of the luminaire enclosure cover  606 . The even spacing of enclosure fasteners  630  help ensure a flame-tight seal of the luminaire enclosure cover  606  against the luminaire enclosure backing  604 . Additionally, mechanical fasteners  626   a ,  626   b ,  626   c  sandwich the pcb board  622  between the LED protective lens array clamp plate  611  and the luminaire enclosure backing  604 . In the embodiment shown, a plurality of LED arrays  62   o  is configured to emit light through the luminaire lens  612  when powered. Additionally, adaptors  664   a ,  664   b  provide channels for an exterior power or data source (not shown) to communicate electronically with a control board (not shown) of the luminaire  602  or with the pcb board  622 . For example, a controls enclosure  232  may be configured to communicate with the luminaire  602  via the adaptors  664   a ,  664   b  and control the LED arrays  620  or the individual LED elements  623 . The luminaire  602  also includes a standalone battery indicator light  668  configured to indicate a condition of the battery (e.g., a low charge condition, a charged condition, a damaged condition). As will be discussed in further detail below, a standalone flame protected LED optic houses the standalone battery indicator light  668  and provides flame protection for the standalone battery indicator light  668 . 
       FIG. 6 c    illustrates a cross-section of the luminaire  602 . In the embodiment shown, the luminaire  702  includes a hollow compartment  642  disposed on a backside of the luminaire enclosure backing  604 . In the example shown, the hollow compartment  642  contains mounting equipment  671  configured to mount the luminaire enclosure backing  604  (and thereby the luminaire  602 ) to a surface (e.g., a wall, a ceiling, a doorway). The hollow compartment  642  may also be used for storage of electronic components (e.g., a battery, a controls circuit). In the embodiment shown, the volume of the luminaire cavity  628  is determined to prioritize flame protection. Accordingly, the volume of the luminaire cavity  628  is minimized when fabricating the luminaire enclosure  602  so that a flame occurring in the luminaire cavity  628  is accordingly contained. 
       FIGS. 7 a  and 7 b    illustrate a perspective view and a top view, respectively, of another luminaire system  700  including a luminaire enclosure  702 . Enclosure fasteners  730  are positioned along the perimeter edge of the luminaire enclosure cover  706 . The even spacing of enclosure fasteners  730  help ensure a flame-tight seal of the luminaire enclosure cover  706  against the luminaire enclosure backing  704 . Mechanical fasteners  726  fix the LED protective lens array clamp plate  711  over the pcb board  722  by mechanically engaging the luminaire enclosure backing  704  through the pcb board  722 . In the embodiment shown, a plurality of LED arrays  720  is configured to emit light through the luminaire lens  712 . Additionally, aperture  770  provides a way for an exterior power or data source (not shown) to communicate electronically with a control board (not shown) of the luminaire  702  or with the pcb board  722 , as described above, with respect to  FIG. 6 . As with the luminaire of  FIG. 6 , the luminaire  702  includes a standalone battery indicator light  768  configured to indicate a condition of the battery (e.g., a low charge condition, a charged condition, a damaged condition). 
       FIG. 7 c    illustrates a cross-section of the luminaire  702 . In the embodiment shown, the luminaire  702  includes a slim enclosure cover  706  and a slim luminaire enclosure backing  704  joined together by enclosure fasteners  730  (pins, in the embodiment shown). In the embodiment shown, the volume of the luminaire cavity  628  is determined to prioritize flame protection according to a flame protection standard for enclosures. Accordingly, the volume of the luminaire cavity  728  is minimized when fabricating the luminaire enclosure  702  so that a flame occurring in the luminaire cavity  728  is accordingly kept relatively small. Aperture  770  is configured to maintain the flame protected status of the luminaire  702  by forming a flame-tight seal against the materials inserted therein (e.g., wires, a plug). In this way, the luminaire  702  may remain slim and while achieving flame protection as described herein. 
       FIGS. 8 a  and 8 b    illustrate LED protective lens array clamp plates  811   a ,  811   b . The LED protective lens array clamp plates  811   a ,  811   b  include fastener apertures  870   a ,  870   b  configured to receive mechanical fasteners  726  for the purpose of fastening the LED protective lens array clamp plates to the luminaire enclosure backing  804 . The LED protective lens array clamp plates  811   a ,  811   b  also include a plurality of LED protective lens apertures  872   a ,  872   b  configured to receive a variety of LED protective lenses  756  therethrough when the LED protective lens array clamp plate  811   a  or  811   b  is fastened to the luminaire enclosure backing  704  and sandwiches the LED protective lens array  724  and pcb board  722  to the luminaire enclosure backing  704 . 
       FIGS. 9 a  and 9 b    illustrate a standalone battery indicator light lens  974 . The standalone battery indicator light lens  974  comprises an indicator light cavity  976  configured to receive a standalone battery indicator light  768  and to provide flame protection of the type described herein for the standalone battery indicator light  768  when clamped to the pcb board  722  via the LED protective lens array clamp plate  811   a ,  811   b.    
     The foregoing detailed description of the certain exemplary embodiments has been provided for the purpose of explaining the general principles and practical application, thereby enabling others skilled in the art to understand the disclosure for various embodiments and with various modifications as are suited to the particular use contemplated. This description is not necessarily intended to be exhaustive or to limit the disclosure to the exemplary embodiments disclosed. Modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Any of the embodiments and/or elements disclosed herein may be combined with one another to form various additional embodiments not specifically disclosed. Accordingly, additional embodiments are possible and are intended to be encompassed within this specification and the scope of the appended claims. The specification describes specific examples to accomplish a more general goal that may be accomplished in another way. 
     As used in this application, the terms “front,” “rear,” “upper,” “lower,” “upwardly,” “downwardly,” and other orientational descriptors are intended to facilitate the description of the exemplary embodiments of the present application, and are not intended to limit the structure of the exemplary embodiments of the present application to any particular position or orientation. Terms of degree, such as “substantially” or “approximately” are understood by those of ordinary skill to refer to reasonable ranges outside of the given value, for example, general tolerances associated with manufacturing, assembly, and use of the described embodiments.