Hazardous area enclosure with improved mating interface

Abstract

An enclosure (100) includes a cover (102) having a plurality of apertures (114). The enclosure further includes a body (104) having a first surface (126) and a second surface (128) opposite the first surface (126), wherein the first surface (126) is an engagement surface (112) having a plurality of holes (162) corresponding with the cover apertures (114), the body (104) further having at least one sidewall (130, 132, 134, 136) defining a cavity (138). The enclosure (100) further includes a plurality of fasteners (118) that pass through the cover apertures (114) and the corresponding body holes (162), thereby securing the cover (102) to the body (104). The enclosure (100) further includes a slot (170) along the engagement surface (112).

Description

HAZARDOUS AREA ENCLOSURE WITH IMPROVED MATING INTERFACECROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Indian Provisional Application No. 202411027628, filed on April 3, 2024. The disclosure of which is incorporated by reference herein in its entirety.FIELD OF INVENTION

[0002] The present disclosure relates generally to an enclosure. More particularly, the present disclosure relates to an enclosure having a cover and a body wherein the enclosure body includes a slot in an engagement surface.BACKGROUND

[0003] Hazardous area enclosures such as explosion-proof housings and enclosure systems are used in many different industrial applications. Such hazardous area enclosures may be used, for example, in military applications, onboard ships, assembly plants, power plants, oil refineries, petrochemical plants, and other harsh environments. Such hazardous area enclosures are used to protect and encase vulnerable equipment and controls that permit such harsh environments to function properly. Furthermore, such hazardous area enclosures are used to restrict hazardous gases from exiting the enclosure into such hazardous environments.

[0004] Given that these enclosures are utilized in volatile and harsh environments an operator may need to perform maintenance on the equipment contained within the enclosure to ensure the systems operating in the harsh environments are in working order. Maintenance on the equipment within the enclosure may require a complete shutdown of the systems affected and may put the operator in a hazardous environment. In such cases, long shutdowns or delays can result in system inefficiencies and stymie productivity.SUMMARY OF THE INVENTION

[0005] In one embodiment, an enclosure includes a cover having a plurality of apertures. The enclosure further includes a body having a first surface and a second surface opposite the first surface, wherein the first surface is an engagement surface having a plurality of holes corresponding with the cover apertures, the body further having at least one sidewall defining a cavity. The enclosure further includes a plurality of fasteners that pass through the cover apertures and the corresponding body holes, thereby securing the cover to the body. The enclosure further includes a slot along the engagement surface.

[0006] In another embodiment, an enclosure includes a body having a first sidewall, a second sidewall opposite the first sidewall, a third sidewall, and a fourth sidewall opposite the third sidewall, the sidewalls defining a substantially rectangular cavity, and the body includes a flange disposed around a first end of the sidewalls. The enclosure further includes a plurality of holes disposed in the flange. The enclosure further includes a cover coupled to the body by a plurality of fasteners that threadedly engage the threaded holes. The enclosure further includes a plurality of slots disposed along the flange.

[0007] In yet another embodiment, a method of assembling an enclosure includes providing an enclosure cover having a plurality of apertures. The method of assembling an enclosure includes providing an enclosure body having a first surface and a second surface opposite the first surface. The enclosure body further has at least one wall forming a cavity, wherein the first surface of the enclosure body is an engagement surface having a plurality of holes corresponding with the cover apertures, and wherein the engagement surface has at least one slot formed therein. The method of assembling an enclosure includes securing the cover to the enclosure body by fastening a plurality of fasteners via the cover apertures and the holes in the engagement surface.BRIEF DESCRIPTION OF DRAWINGS

[0008] In the accompanying drawings, structures are illustrated that, together with the detailed description provided below, describe exemplary embodiments ofthe claimed invention. Like elements are identified with the same reference numerals. It should be understood that elements shown as a single component may be replaced with multiple components, and elements shown as multiple components may be replaced with a single component. The drawings are not to scale, and the proportion of certain elements may be exaggerated for the purpose of illustration.

[0009] Figure 1 is a perspective view of a prior art enclosure,

[0010] Figure 2 is an assembly view of one embodiment of an enclosure having an enclosure cover and an enclosure body,

[0011] Figure 3 is a section view of Section A-A of Figure 2,

[0012] Figure 4 is a perspective assembly view of an alternative embodiment of an enclosure,

[0013] Figure 5A is a perspective view of an interface between a prior art enclosure cover and a prior art enclosure body,

[0014] Figure 5B is a pressure map showing the contact pressure along the interface of Figure 5A,

[0015] Figure 6A is a perspective view of one embodiment of an interface between an enclosure cover and an enclosure body, and

[0016] Figure 6B is a pressure map showing the contact pressure along the interface of Figure 6A.DETAILED DESCRIPTION

[0017] As defined herein, an enclosure is any type of cabinet or housing inside of which is disposed one or more electrical devices. Such electrical devices can include, but are not limited to, variable frequency drives (VFDs), controllers, relays (e.g., solid state, electro-mechanical), contactors, breakers, switches, transformers, inverters, converters, fuses, electrical cables, thermo-electric coolers (TECs), heating elements, air moving devices (e.g., fans, blowers), terminal blocks, wire nuts, and electrical conductors. In some cases, an electrical device can generate heat when operating. Electrical devices can also include mechanical components or mechanical devices that are controlled by an electrical device. Examples of an enclosure can include, but are not limited to, an electrical connector, a junction box,a motor control center, a breaker cabinet, an electrical housing, a conduit, a control panel, an electrical receptacle, a lighting panel, a lighting device, a relay cabinet, an indicating panel, and a control cabinet.

[0018] In certain exemplary embodiments, enclosures are subject to meeting certain standards or requirements. For example, the National Electric Code (NEC), the National Electrical Manufacturers Association (NEMA), the International Electrotechnical Commission (IEC), and the Institute of Electrical and Electronics Engineers (IEEE) set standards for enclosures, wiring, and electrical connections.

[0019] According to further exemplary embodiments, enclosures as described herein can be located in any type of environment (e.g., indoors, outdoors, in a climate-controlled room). Even further exemplary enclosure embodiments can be located in hazardous environments. As defined herein, a hazardous location is any location where the enclosure can be exposed to extreme conditions. Extreme conditions can include, but are not limited to, high temperatures, low temperatures, temperature fluctuations, corrosion, humidity, chemicals, vibrations, and dust. More information about hazardous locations and hazardous location enclosures can be found, for example, in Articles 500-506 and Articles 510-517 of the National Electric Code, which is incorporated herein by reference.

[0020] Examples of a hazardous location in which example embodiments can be used can include, but are not limited to a drilling rig (as for oil, gas, or water), a production rig (as for oil or gas), a refinery, a chemical plant, a petrochemical plant, a power plant, a mining operation, and a steel mill. In a hazardous environment, it may be desirable or required for an enclosure to be explosion-proof. In one or more example embodiments, an explosion-proof enclosure (also known as a flame-proof enclosure) is an enclosure that is configured to contain an explosion that originates inside the enclosure. Such explosion-proof enclosures may have a flame path.

[0021] In one or more example embodiments as discussed below, an explosionproof enclosure is subject to meeting certain standards or requirements. For example, NEMA sets standards with which an electrical enclosure must comply in order to qualify as an explosion-proof enclosure. Specifically, NEMA Type 7, Type 8, Type 9, and Type 10 enclosures set standards with which an explosion-proofenclosure within certain hazardous locations must comply. For example, a NEMA Type 7 standard applies to electrical enclosures constructed for indoor use in certain hazardous locations. Hazardous locations may be defined by one or more of a number of authorities, including but not limited to the National Electric Code (e.g., Class 1, Division I) and UL (e.g., UL 1203). For example, a Class 1 hazardous area under the National Electric Code is an area in which flammable gases or vapors may be present in the air in sufficient quantities to be explosive.

[0022] Referring to Figure 1, prior art enclosures 10 include a cover 12 and a body 14. The cover 12 engages and mates with the body 14 at an interface 16. The cover 12 includes various electrical devices, components, or controls 18 that are disposed on the surface of the cover 12. The enclosure cover 12 is secured to the body 14 by a plurality of threaded fasteners 20, such as bolts. The cover 12 protects various internal electrical devices (not shown) that are disposed within the enclosure from areas made hazardous by the continuous or abnormal presence of flammable gases, flammable vapors, and combustible dust. The cover 12 further protects the various internal electrical devices from moisture in areas subject to weather, dampness, and corrosion. In the prior art enclosure 10 depicted in Figure 1, the fasteners 20 extend around the entire perimeter of the cover 12 and body 14 at the interface 16, to ensure that the cover 12 is secured to the body 14. Unfastening the significant number of fasteners 20 from the enclosure 10 to access the internal electrical devices therein is time consuming and inefficient. Additionally, accessing the enclosure 10 may be hazardous to an operator conducting maintenance because an increased amount of time exposed to the hazardous conditions can increase risk of harm to the operator. Therefore, a complete shutdown of the systems affected may be necessary in order reduce a user’s exposure to the hazardous environment. Long shutdowns or delays can result in system inefficiencies and stymie productivity. The present disclosure overcomes these deficiencies and other deficiencies in the prior art.

[0023] An exemplary embodiment of an enclosure 100 is depicted in Figures 2-3. In general, the enclosure 100 includes an enclosure cover 102 and an enclosure body 104, and the enclosure cover 102 is configured to contain and protect electricaldevices 106 housed within the enclosure body 104 from hazardous environments. As discussed above such environments can be hazardous due to continuous or abnormal presence of flammable gases, flammable vapors, and combustible dust. Furthermore, the environments can be hazardous due to moisture that could damage the electrical devices such as in areas subject to weather, dampness, and corrosion.

[0024] In the illustrated embodiment, the enclosure cover 102 includes a first surface 108 and a second surface 110, wherein the first surface 108 faces outwards towards the environment and the second surface 110 faces towards the enclosure body 104. The second surface 110 of the enclosure cover 102 is an engagement surface 112. The enclosure cover 102 includes a plurality of apertures 114 defining fastening points around the perimeter of the enclosure cover 102, wherein the apertures 114 are configured to receive a fastener 118 therein. In the illustrated embodiment, the fasteners 118 are bolts configured to be coupled with a nut. In alternative embodiments (not shown), the fasteners may include, without limitation, screws (which may be coupled with a nut), clamps, brackets, or a combination thereof.

[0025] The enclosure cover 102 can further include one or more features configured for operator interaction while the enclosure 100 is sealed in a closed position (e.g., when the cover 102 is fastened to the body) 104. In the illustrated embodiment, one or more external electrical devices 120 are located on the enclosure cover 102. The enclosure cover 102 further includes a mechanical switch 122 that is configured to operate an electrical switch 124 located inside the enclosure 100 while the enclosure is closed.

[0026] In the illustrated embodiment, the enclosure body 104 includes a first surface 126 and a second surface 128 opposite the first surface 126. The enclosure body 104 further includes a plurality of sidewalls 130, 132, 134, 136 extending between the first and second enclosure body surfaces 126, 128. The enclosure body is substantially rectangular such that the plurality of sidewalls includes a first sidewall 130, a second sidewall 132 opposite the first sidewall 130, a third sidewall 134, and a fourth sidewall 136 opposite the third sidewall 134 such that the sidewalls 130, 132, 134, 136 define a substantially rectangular cavity 138. Inalternative embodiments (not shown), the enclosure body is square, circular, or has any other geometric shape. In such alterative embodiments, sidewalls of the enclosure body define a cavity that is square, circular, or any other geometric shape that corresponds with the enclosure body shape. In even further alternative embodiments, and enclosure body includes a cavity of a suitable geometric shape that is not defined by or does not correspond with the shape of the enclosure body (e.g., a rectangular enclosure body including a substantially circular cavity).

[0027] The enclosure body further includes a mounting plate 140 that is affixed to the inner face 142 of the enclosure body second surface 128. The mounting plate 140 receives the electrical devices 106 for securely mounting the electrical devices 106 within the cavity 138. The enclosure body 104 further includes one or more mounting brackets 146 disposed on an outer face 148 of the enclosure body second surface 128.

[0028] The first surface 126 of the enclosure body 104 is an engagement surface of a body flange 150. The body flange 150 abuts and engages with the cover engagement surface 112 when the cover 102 is in the closed position, such that the second surface 110 of the cover 102 contacts the first surface 126 of the body 104. The body flange 150 extends perpendicularly about the perimeter of the sidewalls 130, 132, 134, 136. The enclosure body 104 further includes a plurality of holes 162 that define fastening points along the perimeter of the body flange 150. The holes 162 of the enclosure body 104 align and correspond with the cover apertures 114 such that each of the enclosure body holes 162 are configured to receive the fastener 118 that is received by the corresponding enclosure cover aperture 114 to secure the cover 102 in the closed position. In an alternate embodiment, the apertures 114 and holes 162 each include a fastener engagement feature such as a threaded internal diameter to threadedly engage the fasteners 118 therein. The enclosure includes at least one hinge 166 that is secured to one side of the enclosure cover 102 and a corresponding side of the enclosure body 104 such that when all the fasteners 118 are removed, the enclosure cover 102 may swing outward to an open position to allow access to the cavity 138.

[0029] In the illustrated embodiment, the body flange 150 further includes slots 170, which may also be referred to as a channel, a groove, a cut-out, etc. Each slot 170 extends along a length of the body flange 150 between at least two holes 162. While two slots 170 are shown in the illustrated embodiment, it should be understood that three or more slots may be employed. Furthermore, it should be understood that less than two slots may be used. For example, while the body flange 150 of the illustrated embodiment only has slots along its longitudinal surfaces, alternative embodiments also include slots on the lateral surfaces.

[0030] The slot 170 is depicted as a substantially rectangular shaped slot. In alternate embodiments, the slot is an oval shape or other suitable geometric shape. In the illustrated embodiment, the slot includes a slot opening 172, a first sidewall 174, a second sidewall 176, and a slot floor 178, wherein the sidewalls 174, 176 are substantially parallel to one another, and the slot floor 178 is substantially perpendicular to the sidewalls 174, 176. In an alternate embodiment, the sidewalls 174, 176 are not substantially parallel such that the slot floor 178 is wider than the slot opening 172, or the slot floor 178 is narrower than the slot opening 172. In further alternate embodiments, the slot 170 does not have a slot floor 178. In such further alternate embodiments, the sidewalls 174, 176 are angled to meet at an apex or are curved to form a rounded groove. In the illustrated embodiment, the width of the slot 170 is less than the width of the body flange 150. Furthermore, the depth of the slot 170 is less than the depth of the body flange 150. However, in alternate embodiments, the slot 170 depth is equal to the depth of the body flange 150 such that the slot 170 is a pass-through aperture or pass-through groove.

[0031] In the illustrated embodiment, the enclosure 100 includes a flame path 180. The flame path 180 is an air gap disposed between the cover engagement surface 112 and the body flange 150. The flame path 180 is created by the compressive force of securing the enclosure cover 102 to the body flange 150. The flame path 180 creates an explosion-proof joint between the enclosure cover 102 and the body flange 150. The flame path 180 is a nominal air gap, having a width W1 as close to zero (0.0) inches (0.0 cm) as possible. By having a narrow flame path 180 to travel, any hot gasses or flaming gases from an explosion that occurswithin the enclosure 100 cool as the gases slowly travel along the restrictive flame path 180 to exit the enclosure 100. By restricting the egress of the hot or flaming gases, the flame path 180 reduces the risk of a potential larger explosion in an environment outside of the enclosure 100. The passage of the gases from the interior of the enclosure 100 to the exterior of the enclosure 100 is denoted by the arrow in Figure 3. In the illustrated embodiment, the flame path 180 is depicted as a flat surface. However, it is to be appreciated that in an alternate embodiment the flame path is configured as a threaded surface, a serrated surface, or other suitable nonlinear surface geometries, or a combination thereof.

[0032] In the illustrated embodiment, distance DI is the distance of the flame path 180 from the interior of the housing 104 to the slot 170. In the illustrated embodiment, distance DI has a minimum length of 1 inch (2.54 cm) in accordance with NEMA standards. The end limit of distance DI is dependent upon the length of the cover engagement surface 112 and the body flange 150. It is to be appreciated that in alternate embodiments, that distance DI can be adapted to adhere to evolving safety standards. In the illustrated embodiment, distance D2 is the length of the flame path from the interior of the housing 104 to the exterior of the housing 104, such that flame path 180 extends across the slot 170 and across the terminal edges 182, 184 of the cover engagement surface 112 and body flange 150.

[0033] Referring now to Figure 4, which depicts an alternate embodiment of an enclosure 200. The enclosure 200 includes an enclosure cover 202 and an enclosure body 204. The enclosure cover 202 includes a first surface 206 and a second surface 208, wherein the first surface 206 faces outwards towards the environment and the second surface faces towards the enclosure body 204. The second surface 206 of the enclosure cover 202 is an engagement surface 210. The enclosure cover 202 includes a plurality of apertures (not shown) disposed along the perimeter of the enclosure cover 202, wherein the apertures are configured to receive fasteners (not shown) therein. In the illustrated embodiment, the enclosure body 204 includes a first surface 214 and a second surface 216 opposite the first surface 214. The enclosure body 204 further includes a plurality of sidewalls 218,220, 222, 224 extending between the first and second enclosure body surfaces 214, 216 wherein the sidewalls 218, 220, 222, 224 define a cavity 226.

[0034] The first surface 214 of the enclosure body 204 is an engagement surface 230. The body engagement surface 230 abuts and engages with the cover engagement surface 210 when the cover 202 is in a closed position. The enclosure body 204 further includes one or more holes 234 along the perimeter of the body engagement surface 230. The holes 234 of the enclosure body 204 align and correspond with the cover apertures such that each of the enclosure body holes 234 are configured to receive a corresponding fastener therethrough. The body engagement surface 230 further includes a plurality of slots 236, 238. The slots 236, 238 may also be referred to as a channel, a groove, a cut-out, etc. In the illustrated embodiment, the slots 236, 238 are comprised of a combination of slots 236 that extend along a length of the body engagement surface 230 and slots 238 that extend along a width of the body engagement surface 230. In an alternate embodiment, the body engagement surface 230 only includes slots that extend along a length of the body flange 204. In a further alternate embodiment, the body engagement surface 230 only includes slots that extend across a width of the body flange 204. In the illustrated embodiment, the slots 236, 238 are depicted as substantially rectangular shaped slots 236, 238. In alternate embodiments, the plurality of slots 236, 238 have an oval shape or other suitable geometric shape.

[0035] The slots in the embodiments described above and depicted in Figures 2-4 are each configured to reduce the amount of fasteners needed to secure the enclosure cover to the enclosure body without sacrificing safety. Notably, the introduction of slots increases safety. The introduction of slots increases safety because each slot reduces the effective contact area at the interface between the cover engagement surface and body flange or engagement surface, which thereby increases the contact pressure at each fastener along the interface between the cover engagement surface and body flange or engagement surface. Furthermore, by increasing the contact pressure at the interface, the slots reduce the number of fasteners necessary to secure the enclosure cover to the enclosure body, whichthereby increases maintenance and manufacturing efficiency and decreases maintenance and manufacturing cost.

[0036] Figures 5A-5B collectively depict a prior art case study Case A. Case A is a representative case study depicting one possible exemplary embodiment of the prior art. All measurements and numbers are for representative or comparative purposes. Figure 5A depicts a model 300 of an interface 302 between a cover engagement surface 304 and a body flange 306, wherein the cover engagement surface 304 is secured to the body flange 306 by a bolt 308. The interface 302 does not include a slot, in accordance with the exemplary prior art enclosure 10 as depicted in Figure 1. Figure 5B depicts a pressure map of the contact pressure along the interface 302 of the Case A model 300. As shown in Figure 5A the bolt 308 is simulated to have a pretension of 2000 Newton (N). As shown in Figure 5B the contact pressure at the prior art interface 302, when the contact pressure is greater than 5.0 Megapascal (MPa), is observable up to approximately 10 mm in diameter measured across the center of the bolt. Figure 5B includes point Pl, point Pl is a representative measurement which is measured at a boundary where the contact pressure is less than 5.0 MPa measured across the center of the bolt. The contact pressure at point Pl is approximately 4.2 MPa.

[0037] Figures 6A-6B, collectively depict a case study Case B. Case B is a representative case study depicting one possible exemplary embodiment of the present disclosure to illustrate the increased contact pressure in Case B when compared to prior art Case A. All measurements and numbers are for representative or comparative purposes. Figure 6A depicts a model 400 of an interface 402 between a cover engagement surface 404 and a body flange 406 in accordance with an embodiment of the present disclosure. The cover engagement surface 404 is fastened to the body flange 406 by a bolt 408. The body flange 406 includes a first slot 410 and a second slot 412 that extend lengthwise along the engagement surface of the body flange 406 at the interface 402 with the cover engagement surface 404. The bolt 408 is disposed between the first and second slots 410, 412. Figure 6B depicts a pressure map of the contact pressure of the Case B model 400. As shown in Figure 6A the bolt 408 is simulated to have a pretension of 2000 Newton (N).As shown in Figure 6B, the contact pressure at the interface 402, when the pressure is greater than 5.0 Megapascal (MPa), is observable at approximately 17 mm in diameter across the center of the bolt 408. This increase in distance of observable pressure greater than 5.0 MPA is a 70% increase from the prior art interface 302 in Case A. Figure 6B includes point P2, which is taken from the same distance from the center of the bolt 408 as point Pl in Case A. The contact pressure at point P2 is approximately 10.5 MPa. The pressure at point P2 is an approximately 150% increase in contact pressure in comparison to the contact pressure at the point Pl on the prior art interface 302 in Case A.

[0038] A method of assembling an enclosure includes providing an enclosure having a plurality of apertures. The method further includes providing an enclosure body having a first surface opposite of the first surface. The enclosure body further having at least one wall disposed between the first surface and the second surface forming a cavity, wherein the first surface of the enclosure body is an engagement surface having a plurality of holes corresponding with the cover apertures. The method further includes providing a slot along the engagement surface of the enclosure body. The method further includes securing the cover to the enclosure body by fastening a plurality of fasteners via the cover apertures and the holes in the engagement surface.

[0039] In an alternate embodiment, the method further includes securing the enclosure cover to the enclosure body includes providing a flame path comprising an air gap between the enclosure cover and the enclosure body, wherein the flame path is at least one inch long.

[0040] In a further alternate embodiment, providing a slot includes machining a slot extending along the length of the engagement surface.

[0041] In an even further alternate embodiment, the method providing a slot includes machining a slot extending across the width of the engagement surface.

[0042] To the extent that the term “includes” or “including” is used in the specification or the claims, it is intended to be inclusive in a manner similar to the term “comprising” as that term is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term “or” is employed (e.g., A or B)it is intended to mean “A or B or both.” When the applicants intend to indicate “only A or B but not both” then the term “only A or B but not both” will be employed. Thus, use of the term “or” herein is the inclusive, and not the exclusive use. See, Bryan A. Gamer, A Dictionary of Modem Legal Usage 624 (2d. Ed. 1995). Also, to the extent that the terms “in” or “into” are used in the specification or the claims, it is intended to additionally mean “on” or “onto.” Furthermore, to the extent the term “connect” is used in the specification or claims, it is intended to mean not only “directly connected to,” but also “indirectly connected to” such as connected through another component or components. Terms such as “first”, “second”, “top”, “bottom”, “side”, “width”, “length”, “inner”, and “outer” are used merely to distinguish one component (or part of a component or state of a component) from another. Such terms are not meant to denote a preference or a particular orientation and are not meant to limit embodiments of the enclosures.

[0043] While the present application has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the application, in its broader aspects, is not limited to the specific details, the representative apparatus and method, and illustrative examples shown and described.

Claims

CLAIMSWhat is claimed is:

1. An enclosure comprising: a cover having a plurality of apertures; a body having a first surface and a second surface opposite the first surface, wherein the first surface is an engagement surface having a plurality of holes corresponding with the cover apertures, the body further having at least one sidewall defining a cavity; a plurality of fasteners that pass through the cover apertures and the corresponding body holes, thereby securing the cover to the body; and a slot along the engagement surface.

2. The enclosure of claim 1, wherein the engagement surface is the surface of a flange.

3. The enclosure of claim 1, wherein the slot extends along a length of the engagement surface.

4. The enclosure of claim 1, wherein the slot includes a plurality of slots.

5. The enclosure of claim 4, wherein the plurality of slots extends along a length of the engagement surface.

6. The enclosure of claim 5, wherein the holes are disposed between two slots.

7. The enclosure of claim 4, wherein the plurality of slots extends across a width of the engagement surface.

8. The enclosure of claim 7, wherein each slot extends across a width of the engagement surface between at least two holes.

9. The enclosure of claim 1, further comprising an air gap between the body engagement surface and the cover, thereby defining a flame path.

10. The enclosure of claim 9, wherein the slot is spaced at least one inch away from an inner surface of one of the sidewalls.

11. The enclosure of claim 9, wherein the slot is a rectangular shaped slot.

12. The enclosure of claim 9, wherein the slot is an oval shaped slot.

13. An enclosure comprising: a body having a first sidewall, a second sidewall opposite the first sidewall, a third sidewall, and a fourth sidewall opposite the third sidewall, the sidewalls defining a substantially rectangular cavity, and the body includes a flange disposed around a first end of the sidewalls; a plurality of holes disposed in the flange; a cover coupled to the body by a plurality of fasteners that threadedly engage the threaded holes; and a plurality of slots disposed along the flange.

14. The enclosure of claim 13, wherein the slots extend along a length of the flange.

15. The enclosure of claim 13 wherein the slots extend across a width of the flange.

16. The enclosure of claim 13, wherein the slots are a combination of at least one slot extending along a length of the flange and at least one slot extending across a width of the flange.

17. The enclosure of claim 13, wherein the slot is spaced at least one inch away from an inner surface of one of the sidewalls.

18. The enclosure of claim 13, further comprising a mounting bracket disposed on an outer surface off the body.

19. A method of assembling an enclosure comprising: providing an enclosure cover having a plurality of apertures;providing an enclosure body having a first surface and a second surface opposite the first surface, the enclosure body further having at least one wall forming a cavity, wherein the first surface of the enclosure body is an engagement surface having a plurality of holes corresponding with the cover apertures, and wherein the engagement surface has at least one slot formed therein; and securing the cover to the enclosure body by fastening a plurality of fasteners via the cover apertures and the holes in the engagement surface.

20. The method of claim 17, wherein securing the enclosure cover to the enclosure body includes securing the cover such that an air gap is disposed between the enclosure cover and the enclosure body, thereby defining a flame path.

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