Abstract:
Explosion-proof enclosures having one or more flame paths and one or more grooves for protecting the flame paths and/or assisting in accessing and measuring the flame paths, and methods for coating the explosion-proof enclosures.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 62/306,357, filed Mar. 10, 2016, which application is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    Explosion proof enclosures are commonly used in hazardous locations in order to contain explosions that may occur within the enclosure and prevent sparks occurring within the enclosure from igniting vapors, gases, or other materials in the area surrounding the enclosure. Hazardous locations may include, for example, aircraft hangars, gasoline stations, marine vessels, rigs, paint finishing locations, agricultural areas, etc. 
         [0003]    The National Electric Code (NEC®) defines classes and divisions of hazardous locations, as well as requirements for explosion proof enclosures used in such locations. For example, a Class I hazardous location or area is one in which flammable gases or vapors are/could become present in concentrations sufficient to produce explosive and/or ignitable mixtures. Typical class I areas can include, for example, areas in marine vessels, on-shore and off-shore rigs, and petroleum processing facilities. Within Class I, a Division 1 area or location includes: one where the atmosphere of the area is expected to contain explosive mixtures of gases, vapors or liquids during normal working operations; one where ignitable concentrations frequently exist because of repair or maintenance operations; or one where there is release of ignitable concentrations of gases or vapors due to equipment breakdown, while at the same time causing electrical equipment failure. A Class I, Division 2 hazardous location includes: one where flammable liquids or gases are handled, but not expected to be in explosive concentrations, with the possibility of explosive concentrations resulting from an accidental rupture or other unexpected incident; one where ignitable gases or vapors are normally prevented from accumulating by positive mechanical ventilation, but could exist in ignitable quantities if there is a failure in the ventilation system; and areas adjacent to Class I, Division 1 locations where it is possible for ignitable concentrations of gas/vapors to enter the area due to lack of proper ventilation. Additional classes and divisions of hazardous locations are known in the art. 
         [0004]    Explosion-proof enclosures rated for use in hazardous locations are typically equipped with one or more flame paths. Flame paths are designed for the passage and escape of burning gas resulting from an ignition that may take place within the enclosure itself (e.g., as a result of electrical arcing). As the burning gas passes through a flame path, the gas cools before being vented via the flame path into the atmosphere, thereby preventing the burning gas from igniting the volatile atmosphere in the hazardous location. 
         [0005]    During the manufacturing and assembly of an explosion-proof enclosure, protecting the flame paths is critical to producing a safe product that conforms to regulations. A flame path located near an edge of a component of an enclosure is susceptible to being damaged when the component is handled (e.g., if the edge comes in contact with machinery or other objects) during the manufacture and assembly. 
         [0006]    In addition, painting or otherwise coating exposed surfaces of enclosure components can lead to paint buildup at or near a flame path. Such paint accumulation can prevent access to the flame path (e.g., with a tool designed to measure the flame path to ensure it meets safe operating characteristics periodically during the lifetime of the enclosure). Furthermore, the maximum tolerance between adjacent components of explosion-proof enclosures is generally small. Paint/coating buildup on one component at or near a junction with another component can create unsafe gaps between components that exceed maximum tolerances. 
         [0007]    There is a need for improved flame path protection and maintenance in explosion-proof enclosures. 
       SUMMARY 
       [0008]    One aspect of the present disclosure relates to an explosion-proof enclosure comprising a first housing piece, a second housing piece coupled to the first housing piece, the first housing piece having a surface disposed at a flame path of the enclosure; and a groove disposed in the first housing piece, the groove surrounding the surface and following an outer perimeter of the second housing piece, the second housing piece at least partially covering the groove. 
         [0009]    Another aspect of the present disclosure relates to an explosion-proof enclosure comprising a first housing piece, the first housing piece comprising an outer edge; a second housing piece; a flame path defined by a junction of the first housing piece and the second housing piece; and a groove, the groove being at least partially disposed at the outer edge of the first housing piece and abutting the flame path. 
         [0010]    A further aspect of the present disclosure relates to an explosion-proof enclosure comprising a first housing piece having an outer edge, first and second areas, and a surface disposed at a first flame path of the enclosure; a second housing piece coupled to the first area of the first housing piece; a first groove disposed in the first housing piece, the first groove surrounding the surface and following an outer perimeter of the second housing piece, the second housing piece partially covering the first groove; a third housing piece coupled to the second area of the first housing piece; a second flame path defined by a junction of the first housing piece and the third housing piece; and a second groove, the second groove being at least partially disposed at the outer edge of the first housing piece and abutting the second flame path. 
         [0011]    A further aspect of the present disclosure relates to a method for coating an explosion-proof enclosure, the enclosure comprising a cover and a base, the base comprising a surface configured to form a flame path between the base and the cover, the base further comprising a groove that surrounds the flame path, the groove following an outer perimeter of the cover, the method comprising the steps of: removably securing a coating mask on the base such that the coating mask covers the flame path and at least a portion of the groove; applying a coating material to the base to coat at least one exposed surface of the enclosure, such that coating material enters the groove; and removing the mask from the base. 
         [0012]    Still a further aspect of the present disclosure relates to a method for coating an explosion-proof enclosure, the enclosure comprising a first housing piece and a second housing piece, the first housing piece comprising a surface configured to form a flame path between the first housing piece and the second housing piece, the first housing piece further comprising a groove that surrounds the flame path, the groove following an outer perimeter of the second housing piece, the method comprising the steps of: removably securing a coating mask on the first housing piece such that the coating mask covers the flame path and at least a portion of the groove; applying a coating material to the first housing piece to coat at least one exposed surface of the enclosure, such that coating material enters the groove; and removing the mask from the first housing piece. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1A  is a bottom, front isometric view of an example explosion-proof enclosure in accordance with the present disclosure. 
           [0014]      FIG. 1B  is a bottom, rear isometric view of the explosion-proof enclosure of  FIG. 1A . 
           [0015]      FIG. 2  is a bottom, front isometric view of a first housing piece of the explosion-proof enclosure of  FIG. 1 . 
           [0016]      FIG. 3  is a bottom view of the first housing piece of  FIG. 2 . 
           [0017]      FIG. 4  is a top view of the first housing piece of  FIG. 2 . 
           [0018]      FIG. 5  is an end view of the first housing piece of  FIG. 2 . 
           [0019]      FIG. 6  is a side view of the first housing piece of  FIG. 2 . 
           [0020]      FIG. 7  is a top view of a second housing piece of the explosion-proof enclosure of  FIG. 1 . 
           [0021]      FIG. 8  is an isometric view of a third housing piece of the explosion-proof enclosure of  FIG. 1 . 
           [0022]      FIG. 9  is an expanded isometric cross-sectional view of a portion of the explosion-proof enclosure of  FIG. 1 . 
           [0023]      FIG. 10  is an end view of the call-out portion  10  of  FIG. 9 . 
           [0024]      FIG. 11  is an expanded isometric cross-sectional view of a further portion of the explosion-proof enclosure of  FIG. 1 . 
           [0025]      FIG. 12  is an end view of the call-out portion  12  of  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Various embodiments will be described in detail with reference to the drawings, wherein like reference numerals represent like parts and assemblies throughout the several views. Reference to various embodiments does not limit the scope of the claims attached hereto. Additionally, any examples set forth in this specification are not intended to be limiting and merely set forth some of the many possible embodiments for the appended claims. The figures are not necessarily drawn to scale. 
         [0027]    Many hazardous areas require artificial lighting so that people working in the area have adequate visibility for their activities and environments. Lighting fixtures carry a risk of ignition, from arcing or other forms of sparking. Therefore, lighting fixtures for hazardous locations are specially configured to prevent burning gas from escaping the fixture and entering the volatile atmosphere of the hazardous area. Details of the present disclosure will now be discussed with reference to a particular embodiment of an explosion proof enclosure, namely, a light fixture. It should be appreciated, however, that the inventive principles of this disclosure are not limited to the described embodiment, and can be suitably applied to a variety of explosion-proof enclosures. 
         [0028]      FIG. 1A  is a bottom, front isometric view of an example explosion-proof enclosure  100  in accordance with the present disclosure.  FIG. 1B  is a bottom, rear isometric view of the explosion-proof enclosure  100  of  FIG. 1A . Throughout this disclosure,  FIGS. 1A and 1B  are referred to collectively as  FIG. 1 . With reference to  FIG. 1 , the explosion-proof enclosure  100  is generally defined by a bottom  102 , a top  104 , a front  106 , a rear  108 , a first side  110 , and a second side  112 . Typically, the top  104  will be mounted to a wall, ceiling or other structure in the hazardous environment, and light produced by the enclosure  100  passes through the bottom  102 . 
         [0029]    Throughout this disclosure, with respect to the enclosure  100 , references to orientation (e.g., front(ward), rear(ward), in front, behind, above, below, high, low, back, top, bottom, under, underside, etc.) of structural components and positions shall be defined by the enclosure&#39;s bottom  102 , top  104 , front  106 , and rear  108  as just defined with reference to  FIG. 1 , regardless of how the enclosure may be positioned in the field, during manufacturing or assembly, or otherwise. Words such as “interior” or “interiorly” are defined relative to the exterior of the enclosure  100 , which is defined by its bottom  102 , top  104 , front  106 , rear  108 , first side  110  and second side  112 . 
         [0030]    With reference to  FIG. 1 , the example explosion-proof enclosure  100  includes a first housing piece (or base)  114 , a second housing piece (or first cover)  116 , and a third housing piece (or second cover)  118 . The second housing piece  116  and the third housing piece  118  are configured to be mounted to the base  114  to cover portions of the base  114 . The first housing piece  114  includes a first area  113  and a second area  115 . The first area  113  of the first housing piece  114 , and the second housing piece  116  are removably coupled together with coupling means (e.g., one or more screws, bolts, clips or other fasteners)  120 . The third housing piece  118  and the second area  115  of the first housing piece  114  are removably coupled together with coupling means (e.g., one or more screws, bolts, clips or other fasteners)  122 . In this example, an electrically powered lighting component  124  is disposed in the first housing piece  114 . The second housing piece  116  secures the lighting component  124  in place in the first housing piece  114 . In addition, in this example, a driver for powering and/or controlling the lighting component  124  is housed in a space between the first housing piece and the third housing piece. Passageways  126  enable electrical connectivity between the driver and the lighting component  124 . During manufacture of the enclosure  100 , electrical wiring can pass from the second area  115  via the port  147  into the passageways  126  ( FIGS. 2, 3 ) of the first housing piece  114 , connecting to the lighting component  124  via the port  145  ( FIG. 3 ) in the first area  113 . After wiring has been routed and completed through the enclosure  100 , the ends of the passageways  126  can be plugged, e.g., with set screws. Connectivity to power and/or control sources external to the enclosure  100  can be routed to the driver through one or both of the sealable ports  127  ( FIG. 1B ). 
         [0031]      FIG. 2  is a front, bottom isometric view of the first housing piece  114  of the explosion-proof enclosure  100  of  FIG. 1 .  FIG. 3  is a bottom view of the first housing piece  114  of  FIG. 2 . 
         [0032]    With reference to  FIGS. 2-3 , the first housing piece  114  includes the first area  113 , the second area  115 , and the passageways  126 , as described above. In addition, in this example, the first area  113  includes a bottom  129 , a bridging surface  130 , a flame path surface  131 , and a first groove  132 , and the second area  115  includes a first contact surface  134  and a second groove  136 . The first area  113  includes an edge  138  on three sides. The second area  115  includes a first edge component  140  on a first side, and a second edge component  142  on two sides. A recess  144  in the first area  113  is configured to support the lighting component  124  ( FIG. 1 ). A surface  146  in the second area  115  is configured to support a driver for the lighting component  124  ( FIG. 1 ). In addition, in this example, the first housing piece  114  includes a channel  149 . The channel  149  surrounds the recess  144  and is configured to support a sealing component (e.g., a gasket) to seal off the lighting component. 
         [0033]    The first groove  132  is disposed interiorly to the edge  138 . The bridging surface  130  is disposed interiorly to the first groove  132  and spans a width from the first groove  132  to the flame path surface  131 . The flame path surface  131  is interior to the bridging surface  130  and is disposed at the first flame path  206  ( FIG. 9 ) when abutted against a surface of an adjacent component of the enclosure  100  (e.g., the glass pane  202  shown in  FIG. 9 ). When the first housing piece  114  is coupled to the second housing piece  116  ( FIG. 1 ), the second housing piece  116  covers (but, in some examples, does not contact) the bridging surface  130 . In some examples, when the first housing piece  114  is coupled to the second housing piece  116 , the second housing piece  116  covers at least part of the width of the first groove  132 , e.g., a majority of a width of the first groove  132 . In some examples, the shape of the space bounded by the first groove  132  is at least approximately defined by the outer perimeter  180  ( FIG. 7 ) of the second housing piece  116 . 
         [0034]    The second groove  136  coincides with at least a portion each of the first edge component  140  and the second edge components  142  in the second area  115 . That is, at least a portion of each of the first edge component  140  and the second edge component  142  is recessed relative to the level of the surface  146  corresponding to a depth of the second groove  136 . 
         [0035]    The first contact surface  134  is disposed interiorly to the second groove  136 . When the first housing piece  114  is coupled to the third housing piece  118  ( FIG. 1 ), the third housing piece  118  abuts and contacts the first contact surface  134 . In some examples, when the first housing piece  114  is coupled to the third housing piece  118 , the third housing piece  118  covers at least part of the width of the second groove  136 , e.g., the entirety of the width of the second groove  136 . In some examples, the shape of the space bounded by the second groove  136  is at least approximately defined by the outer perimeter  190  ( FIG. 8 ) of the third housing piece  118 . 
         [0036]    As shown in  FIGS. 2-3 , in some examples, the first groove  132  and the second groove  136  can be optionally adjoined at a juncture  148  between the first area  113  and the second area  115 . The juncture  148  provides groove continuity between the first area  113  and the second area  115 . Typically, the grooves ( 132 ,  136 ) do not themselves require painting/coating. Thus, by providing groove continuity between the first area  113  and the second area  115 , a single (rather than multiple) paint mask can be used on the bottom  129  of the first housing piece  114  when painting the exposed surfaces thereof. 
         [0037]    As just described, to paint exposed surfaces of the first housing piece  114 , one or more masks can be placed on the bottom  129  of the first housing piece  114 , the mask having a shape corresponding to the outer perimeters ( 180 ,  190 ) of the second housing piece  116  ( FIG. 7 ) and the third housing piece  118  ( FIG. 8 ) (or, if using multiple masks, one mask can have a shape corresponding to the outer perimeter of the second housing piece  116  ( FIG. 7 ) and another mask can have a shape corresponding to the outer perimeter of the third housing piece  118  ( FIG. 8 )). The advantages of the first groove  132  and the second groove  136  with respect to the paint/coating masking process will be described in greater detail below in connection with  FIGS. 9-12 . 
         [0038]      FIG. 4  is a top view of the first housing piece  114  of  FIG. 2 . In this example, the first housing piece  114  includes an outer perimeter  150  and a mounting surface  152 . A primary mounting system for the enclosure  100  includes the mounting surface  152 , which can be secured directly to a surface in a hazardous location. Alternatively, one or more securing means, e.g., brackets that adjustably mount to the wings  163  of the mounting surface  152  and are bolted into a wall, ceiling or other fixture, can be coupled to the mounting surface  152  for securing the first housing piece  114  in a hazardous location. Holes  165  ( FIG. 4 ) disposed at or near the corners of the first housing piece  114  can be provided to receive rope or other supporting material that can be tied to a fixture to provide secondary mounting support should the primary mounting support system fail. 
         [0039]      FIG. 5  is an end view of the first housing piece  114  of  FIG. 2 . In this example, the first housing piece  114  includes the passageways  126 , the bottom  129 , and the mounting surface  152 , as described above. In addition, in this example, the first housing piece  114  includes a top  160  (corresponding to the top  104  of the enclosure  100  in  FIG. 1 ), and a plurality of cutouts  162 . The cutouts  162  reduce the overall weight of the first housing piece  114 , the shape and placement of the cutouts  162  being selected to minimize any loss of structural integrity to the enclosure  100 . 
         [0040]      FIG. 6  is a side view of the first housing piece  114  of  FIG. 2 , with the opposing side view being a mirror image thereof. In this example, the first housing piece  114  includes the first area  113 , the second area  115 , and the mounting surface  152 , as described above. In addition, in this example, the first housing piece  114  includes a first end  170  adjacent the first area  113  (and corresponding to the first end  106  of the enclosure  100  of  FIG. 1 ), and a second end  172  adjacent the second area  115  (and corresponding to the second end  108  of the enclosure  100  of  FIG. 1 ). 
         [0041]      FIG. 7  is a top view of the second housing piece  116  of the explosion-proof enclosure  100  of  FIG. 1 . The second housing piece  116  includes an outer perimeter  180 , a bridge covering surface  182 , a recess  183 , a recessed surface  184 , and openings  186 . 
         [0042]    In some examples, and as discussed above, the outer perimeter  180  can define or partially define the shape of a paint mask used to paint the bottom  129  of the first housing piece  114  ( FIG. 2 ). The bridge covering surface  182  covers, but does not contact, the bridging surface  130  of the first housing piece  114  ( FIG. 2 ) when the first housing piece  114  and the second housing piece  116  are coupled together via the coupling means  120 . The recess  183  receives a transparent panel (e.g., a glass pane—see  FIG. 9 ) that abuts the recessed surface  184  and covers the lighting component  124  ( FIG. 1 ) to protect the lighting component  124  and to improve light dispersion. The openings  186  allow light to pass through the second housing piece  116  from the lighting component  124  ( FIG. 1 ). 
         [0043]      FIG. 8  is an isometric view of the third housing piece  118  of the explosion-proof enclosure  100  of  FIG. 1 . In this example, the third housing piece has a top  191  and is defined by an outer perimeter  190 , sides  192  and  193 , and an end  194 . The outer perimeter  190  defines a second contact surface  196 . The third housing piece  118  also includes a cavity  198 . 
         [0044]    In some examples, and as discussed above, the outer perimeter  190  can define or partially define the shape of a paint mask used during a painting process of the bottom  129  of the first housing piece  114  ( FIG. 2 ). In this example, the side  192  corresponds to the second side  112  of the enclosure  100  of  FIG. 1 , the side  193  corresponds to the first side  110  of the enclosure  100  of  FIG. 1 , and the end  194  corresponds to the second end  108  of the enclosure  100  of  FIG. 1 . The second contact surface  196  covers and contacts the first contact surface  134  of the first housing piece  114  ( FIG. 2 ) when the first housing piece  114  and the third housing piece  118  are coupled together. The cavity  198  is configured to hold a driver to power and/or control the lighting component  124  ( FIG. 1 ). 
         [0045]      FIG. 9  is an expanded isometric cross-sectional view of a portion of the explosion-proof enclosure  100  of  FIG. 1 . The enclosure  100  includes the first housing piece  114 , the first area  113 , the second housing piece  116 , the coupling means  120 , the lighting component  124 , the passageways  126 , the bridging surface  130 , the first groove  132 , the channel  149 , the mounting surface  152 , the cutouts  162 , and the recessed surface  184 , as discussed above. In addition, in this example, the lighting component  124  includes lighting elements  200 , and the enclosure  100  includes a glass pane  202 , a first gasket  204 , and a first flame path  206 . 
         [0046]    The lighting elements  200  (e.g., light emitting diodes) are selected in type, power, number and configuration to emit light commensurate with the lighting needs of the hazardous location and any applicable hazardous location regulations. 
         [0047]    The glass pane  202  covers the lighting component  124 , and is disposed between the first housing piece  114  and the second housing piece  116 , nesting in the recess  183  ( FIG. 7 ) defined by the recessed surface  184 . Thus, the second housing piece  116  acts as a bezel for the glass pane  202 . In some examples, a spacer element  203  (e.g., a pad) ( FIG. 10 ) is placed between the glass pane  202  and the second housing piece  116 , to ensure an adequate gap between the bridging surface  130  and the bridge covering surface  182 , to enable a measuring tool (e.g., a feeler gauge) to access the first flame path  206 . 
         [0048]    The first gasket  204  is disposed in the channel  149  that surrounds the lighting component  124 . Contact between the first gasket  204  and the glass pane  202  forms a seal around the lighting component  124 . 
         [0049]    The first flame path  206  is a gas pathway formed at a junction where the glass pane  202  and the flame path surface  131  ( FIG. 10 ) of the first housing piece  114  contact each other, and interior to the bridging surface  130 . Burning gas resulting from the lighting component  124 , or the wiring associated therewith, cools as it passes through the first flame path  206  towards the exterior of the enclosure  100 . 
         [0050]    With reference to  FIG. 9 , a majority of the width of the first groove  132  is covered by the second housing piece  116 . However, in this example an access gap  208  between the edge of the second housing piece  116  and an outer edge of the first groove  132  is not covered, enabling a flame path measuring tool (e.g., a feeler gauge) to more easily enter the first groove  132  and thereby access the first flame path  206  via the gap between the bridging surface  130  and the bridge covering surface  182 . 
         [0051]      FIG. 10  is an end view of the call-out portion  10  of  FIG. 9 .  FIG. 10  shows the enclosure  100  with top  102 , the first housing piece  114 , the first area  113 , the second housing piece  116 , the lighting component  124 , the bottom  129 , the bridging surface  130 , the flame path surface  131 , the first groove  132 , the glass pane  202 , the spacer element  203 , the first gasket  204 , the first flame path  206 , and the access gap  208 , as discussed above. In addition, in this example, the first groove  132  includes a beveled side  210 , and the first groove  132  has a width w 1  and a depth d 1 . 
         [0052]    The beveled side  210  can facilitate access of a flame path measuring tool (e.g., a feeler gauge) to the first flame path  206 , by providing a sloped (relative to the top  102 ) surface rather than a perpendicular surface, for the flame path measuring tool to slide along the beveled side  210  and into the gap between the bridging surface  130  and the bridge covering surface  182 . In some examples, the side opposing the beveled side  210  can also be beveled, as shown in  FIG. 10 . This can help, for example, in extracting of a flame path measuring tool from the enclosure  100  following measurement of the first flame path  206 . 
         [0053]    Still with reference to  FIG. 10 , while painting exposed surfaces of the first housing piece  114 , a mask can be placed on the first area  113  on the bottom  129  of the first housing piece  114 , the mask extending to where the edge  212  (i.e., the outer perimeter  180 ) of the second housing piece  116  will be disposed when the enclosure  100  is fully constructed. The painting process can include the application of electrostatically charged coating powder to the exposed surfaces of the first housing piece  114 , which is later melted into an epoxy. 
         [0054]    The properties of the powder (e.g., its electrostatically charged nature) can cause the powder to accumulate at edges and corners, e.g., at the edge of the paint mask covering portions of the bottom  129  of the first housing piece  114 . An area of such paint accumulation could therefore form in a strip along the bottom  129  of the first area  113  of the first housing piece  114  in a shape that corresponds to the shape or portion of the shape of the outer perimeter  180  ( FIG. 7 ) of the second housing piece  116  (i.e., the shape of the mask). The approximate location of a hypothetical accumulation strip is identified as A in  FIG. 10 . 
         [0055]    A strip of coating/paint accumulation as just described can inhibit or prevent necessary access to the first flame path  206  for measuring or monitoring the first flame path  206 . Moreover, such a coating/paint accumulation can cause dangerous spacing between components of the enclosure  100 , such as between the first housing piece  114  and the second housing piece  116 , rendering the enclosure  100  unsuitable in a hazardous location due to the tight tolerances required to make an enclosure explosion-proof. 
         [0056]    The first groove  132  can reduce or prevent undesirable coating/paint accumulation at the mask edge (while still enabling all exposed surfaces to be painted/coated) since the mask edge is disposed over a portion of the the first groove  132 , the first groove  132  acting as a gap between the first housing piece  114  and the edge of the mask that the coating/paint does not bridge. In some examples, the first groove  132  captures excess paint/coating. In addition, beveling the sides of the first groove  132  can reduce sharp (e.g., right angled) edges, thereby further reducing the possibility of paint/coating accumulation. 
         [0057]    In some examples, the width w 1  is in a range from about 0.15 inches to about 0.35 inches. In some examples, the width w 1  is about 0.25 inches. In some examples the depth d 1  is in a range from about 0.015 inches to about 0.035 inches. In some examples, the depth d 1  is about 0.025 inches. Widths and depths outside of these ranges may also be suitable. In some examples, both sides of the first groove  132  are beveled, and an arc formed by rays extending along the beveled sides has an angle of between about 60° and about 120°. In a particular example, this angle is approximately 90°. Angles outside of this range may also be suitable. 
         [0058]      FIG. 11  is an expanded isometric cross-sectional view of a further portion of the explosion-proof enclosure  100  of  FIG. 1 .  FIG. 12  is an end view of the call-out portion  12  of  FIG. 11 . 
         [0059]    With reference to  FIGS. 11-12 , the enclosure  100  having a top  102  includes the first housing piece  114 , the second area  115 , the third housing piece  118 , the coupling means  122 , the bottom  129 , the first contact surface  134 , the second groove  136 , the second edge component  142 , the cutouts  162 , the second contact surface  196  and the cavity  198 , as discussed above. In addition, in this example, the enclosure  100  includes a second flame path  220 , a second gasket  222 , and a channel  224 , and the second groove  136  includes a beveled side  226 . 
         [0060]    The second gasket  222  is disposed in the channel  224  and surrounds the cavity  198  to seal off the contents (e.g., an electrical driver) of the cavity  198 . As shown, the second groove  136  is covered by the third housing piece  118  and coincides with the second edge component  142 , and the first contact surface  134  is interior to the second groove  136 . 
         [0061]    The second flame path  220  is a gas pathway between the first contact surface  134  and the second contact surface  196 , disposed interiorly to the second groove  136 . In this example, the second flame path  220  is disposed between the second groove  136  and the second gasket  222 . Burning gas resulting from the driver, or the wiring associated therewith, cools as it passes through the second flame path  220  towards the exterior of the enclosure  100 . 
         [0062]    The second groove  136  can reduce (e.g., by capturing excess coating/paint in the second groove  136 ) dangerous coating/paint accumulation at the second edge component  142  (and similarly at the first edge component  140  ( FIG. 2 )) that may otherwise occur during masking of the bottom  129  of the second area  115  of the first housing piece  114  when coating/painting the first housing piece  114 . Such undesirable coating/paint accumulation could inhibit access to the second flame path  220  for measurement and/or maintenance, and could also space the third housing piece  118  from the first housing piece  114  beyond acceptable tolerances. 
         [0063]    In addition, the second groove  136  can help protect the second edge component  142  (and similarly the first edge component  140  ( FIG. 2 )) from mechanical damage that could occur during handling of the first housing piece  114  and/or during assembly of the enclosure  100 , thereby protecting the second flame path  220  from such mechanical damage. 
         [0064]    A flame path measuring tool (e.g., a feeler gauge) can be introduced to the second flame path  220  via the second groove  136  at the second edge component  142 .The beveled side  226  can facilitate access of a flame path measuring tool to the second flame path  220 , by providing a sloped surface rather than a perpendicular surface, for the flame path measuring tool to slide along the beveled side  226  and into the second flame path  220 . In addition, beveling the side of the second groove  136  can reduce sharp (e.g., right) angled edges, thereby further reducing the possibility of paint/coating accumulation. 
         [0065]    In some examples, the width w 2  is in a range from about 0.05 inches to about 0.15 inches. In some examples, the width w 2  is about 0.087 inches. In some examples, the depth d 2  is in a range from about 0.015 inches to about 0.035 inches. In some examples, the depth d 2  is about 0.025 inches. With reference to  FIG. 3 , the second groove  136  at the first edge component  140  has a width w 3  in a range from about 0.15 inches to about 0.30 inches. In some examples, the width w 3  is about 0.22 inches. The second groove  136  at the first edge component  140  has a depth in a range from about 0.015 inches to about 0.035 inches. In some examples, the depth is about 0.025 inches. Widths and depths outside of these ranges may also be suitable. In some examples, the second groove  136  at the opposing side of the second area  115  from the first edge component  140  has a width w 4  ( FIG. 3 ) and a depth, corresponding to the width w 3  and the depth, respectively, of the second groove  136  at the first edge component  140 . 
         [0066]    In an example method in accordance with the present disclosure, a base  114  of an explosion-proof enclosure  100  is provided, the enclosure having a cover ( 116 ,  118 ), the base having a surface configured to form a flame path ( 206 ,  220 ) between the base and the cover, the base further comprising a groove ( 132 ,  136 ) that surrounds the flame path ( 206 ,  220 ), the groove ( 132 ,  136 ) following an outer perimeter of the cover ( 116 ,  118 ), the method including: removably securing a coating mask on the base ( 114 ), the coating mask covering the flame path ( 206 ,  220 ) and at least a portion of the groove ( 132 ,  136 ); applying a coating material to the base  114  to coat at least one exposed surface of the enclosure ( 100 ), such that coating material enters the groove; and removing the mask from the base. 
         [0067]    The various embodiments described above are provided by way of illustration only and should not be construed to limit the claims attached hereto. Those skilled in the art will readily recognize various modifications and changes that may be made without following the example embodiments and applications illustrated and described herein, and without departing from the true spirit and scope of the following claims