Apparatus and methods for electrically grounding a load-supporting surface

Apparatus for electrically connecting and grounding at least two mechanically interconnectable, planar mats in a reusable load-supporting surface includes at least one removable, electrically-conductive cover configured to be engaged with each mat and extend at least partially across the top and/or bottom face thereof. Each cover includes at least one conductive interface configured to electrically connect its associated mat with at least one other mat in the load-supporting surface.

FIELD OF THE DISCLOSURE

The present disclosure relates to load-supporting surface technology and, more particularly, to apparatus and methods for electrically grounding a load-supporting surface.

BACKGROUND

Temporary or semi-permanent support surfaces have been used for roadways, remote jobsites, industrial staging areas and the like in an ever-increasing myriad of industries, such as the construction, military, oilfield, transportation, disaster response, utilities and entertainment industries. These support surfaces are often made up of heavy duty, durable, all-weather thermoplastic mats, which are reusable and interlock together to form the support surface. In some instances, it is necessary or desirable to provide apparatus and methods to electrically ground at least a portion of the support surface.

For example, it may be necessary or desirable to use a temporary or semi-permanent electrically grounded support surface as part of an Equi-Potential Zone (EPZ). The EPZ is an arrangement typically designed so that dangerous electric potential differences do not appear across the body of a person working on or near ground-based machinery. An EPZ is often used during projects that involve working in close proximity to an energized power line. For example, in performing overhead power line (OHL) projects, the EPZ may prevent the installation crew from being subject to an electric shock caused by, for example, a circuit flash from the energized line to the conductors being worked on. In the EPZ, the equipment and personnel are on a work surface that is electrically conductive and grounded to provide a natural path for large electrical voltages to flow.

Presently know solutions for temporary, or semi-permanent, electrically grounded support surfaces include the use of aluminum access plates bolted together at each corner. These plates are believed to have one or more disadvantage. For example, the plates may not overlap one another and therefore require a flat underlying surface. Otherwise, the edges of the plate(s) may protrude above the underlying surface and form a trip hazard. For another example, the corners of the plates may need to be bolted together using small straps that may also form trip hazards. Often, these systems require a nut and bolt at each corner with the nut on the underside, an arrangement which is labor intensive and cumbersome. For yet another example, the aluminum plates may have considerable scrap value and thus require 24-hour security to prevent theft. For still a further example, these plates may not be useful or adapted to otherwise serve as support surfaces when electrical grounding is not required or needed.

It should be understood that the above-described features, capabilities and disadvantages are provided for illustrative purposes only and are not intended to limit the scope or subject matter of the appended claims or those of any related patent application or patent. Thus, none of the appended claims or claims of any related application or patent should be limited by the above discussion or construed to address, include or exclude each or any of the above-cited features, capabilities or disadvantages merely because of the mention thereof herein.

Accordingly, there exists a need for improved systems, articles and methods useful in connection with providing an electrically grounded support surface having one or more of the attributes or capabilities described or shown in, or as may be apparent from, the various portions of this patent application.

BRIEF SUMMARY OF THE DISCLOSURE

In some embodiments, the present disclosure involves apparatus for electrically connecting and grounding at least two mechanically interconnectable, planar mats in a reusable load-supporting surface deployed on or near the surface of the earth. The mats are constructed at least partially of impermeable plastic material and have top and bottom faces, multiple sides and at least one edge extending around each side thereof. The apparatus includes a plurality of removable, electrically-conductive covers, each configured to be coupled to another of the respective mats and extend at least partially across the top and/or bottom face thereof. Each cover has at least one conductive interface configured to contact and form an electrically conductive path with at least one conductive interface of an adjacent mat when the mats are mechanically interconnected in the load-supporting surface to electrically connect such mats. At least one grounding rod is configured to be electrically connected between at least one cover and the earth.

In various embodiments, each cover includes an outer frame and an inner mesh portion connected to the outer frame, both constructed at least partially of electrically-conductive material. At least one among the outer frame and the inner mesh portion of each cover has at least one conductive interface configured to electrically connect its corresponding mat to an adjacent mat when the mats are mechanically interconnected in the load-supporting surface.

In many embodiments, a method of electrically connecting and grounding at least two mechanically interconnectable, planar mats in a reusable load-supporting surface deployed on or near the surface of the earth includes releasably coupling each cover to its associated mat so that it stays positioned at least partially across the top surface of the mat until it is disconnected therefrom. Each cover forms at least one conductive interface configured to electrically connect its corresponding mat to another mat when the mats are mechanically interconnected in the load-supporting surface. A first mat is positioned relative to a second mat so that at least one conductive interface of the first mat contacts and forms an electrically conductive path with at least one conductive interface of the second mat. The first and second mats are mechanically, releasably, coupled together. At least one of the first and second mats is grounded.

Accordingly, the present disclosure includes features and advantages which are believed to enable it to advance support surface technology. Characteristics and advantages of the present disclosure described above and additional features and benefits will be readily apparent to those skilled in the art upon consideration of the following detailed description of various embodiments and referring to the accompanying drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Characteristics and advantages of the present disclosure and additional features and benefits will be readily apparent to those skilled in the art upon consideration of the following detailed description of exemplary embodiments of the present disclosure and referring to the accompanying figures. It should be understood that the description herein and appended drawings, being of example embodiments, are not intended to limit the claims of this patent application or any patent or patent application claiming priority hereto. On the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of this disclosure or any appended claims. Many changes may be made to the particular embodiments and details disclosed herein without departing from such spirit and scope.

In showing and describing preferred embodiments in the appended figures, common or similar elements are referenced with like or identical reference numerals or are apparent from the figures and/or the description herein. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness.

As used herein and throughout various portions (and headings) of this patent application, the terms “invention”, “present invention” and variations thereof are not intended to mean every possible embodiment encompassed by this disclosure or any particular claim(s). Thus, the subject matter of each such reference should not be considered as necessary for, or part of, every embodiment hereof or of any particular claim(s) merely because of such reference. The terms “coupled”, “connected”, “engaged” and the like, and variations thereof, as used herein and in the appended claims are intended to mean either an indirect or direct connection or engagement. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections.

Certain terms are used herein and in the appended claims to refer to particular components. As one skilled in the art will appreciate, different persons may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. Also, the terms “including” and “comprising” are used herein and in the appended claims in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . . ” Further, reference herein and in the appended claims to components and aspects in a singular tense does not necessarily limit the present disclosure or appended claims to only one such component or aspect, but should be interpreted generally to mean one or more, as may be suitable and desirable in each particular instance.

Referring initially toFIG. 1, an exemplary mat26is shown including an electrically-conductive cover110useful for allowing the mat26to be electrically grounded in accordance with an embodiment of the present disclosure. In this illustration, the mat26serves as a load-supporting surface16deployed on the ground or other surface. In other embodiments, such as shown inFIG. 2, a larger load-supporting surface16that includes multiple interconnected mats26is shown. In that example, the load-supporting surface16includes some mats26having electrically-conductive covers110and other mats26not having electrically-conductive covers. As used herein, the terms “EPZ mat”112and variations thereof refer to a mat26having an electrically-conductive cover110. Thus, when multiple interconnected EPZ mats112are used, each electrically-conducive cover110is useful for allowing the load-supporting surface16to be electrically grounded. In the present embodiment, the load-supporting surface16(e.g.FIGS. 1 and 2) is reusable and capable of supporting the weight of personnel, vehicles and/or equipment thereupon.

Referring toFIG. 3, the mats26may have any suitable form, construction and configuration. Some examples of mats26which may be used in various embodiments of the present disclosure are shown and described in U.S. Pat. No. 5,653,551 to Seaux, entitled “Mat System for Construction of Roadways and Support Surfaces” and issued on Aug. 5, 1997, and U.S. Pat. No. 6,511,257 to Seaux et al., entitled “Interlocking Mat System for Construction of Load Supporting Surfaces” and issued on Jan. 28, 2003, both of which have a common Assignee as the present patent and the entire contents of which are hereby incorporated by reference herein in their entireties. For example, the mats26may be 14′×8′ DURA-BASE® mats currently sold by the Assignee of this patent. If desired, the mats26may be used in connection with any of the components and features described and shown in U.S. patent application Ser. No. 13/790,916 filed Mar. 8, 2013 and entitled “Liquid Containment System for Use with Load-Supporting Surfaces”, U.S. Provisional Patent Application Ser. No. 61/889,171 filed on Oct. 10, 2013 and entitled “Apparatus & Methods for Sealing Around the Opening to an Underground Borehole”, U.S. Provisional Patent Application Ser. No. 61/857,474, filed on Jul. 23, 2013 and entitled “Apparatus and Methods for Providing Illuminated Signals from a Support Surface”, U.S. patent application Ser. No. 14/336,163 filed on Jul. 21, 2014 and entitled “Apparatus and Methods for Providing Illuminated Signals from a Support Surface”, each of which has a common Assignee as the present patent and the entire contents of which are hereby incorporated by reference herein in their entireties.

Still referring toFIG. 3, in the illustrated embodiment, each mat26is flat, or planar, and constructed of impermeable material, such as thermoplastic. The exemplary mat26has a rectangular shape with an opposing pair of short sides28,30, an opposing pair of long sides37,38, and an edge44extending along each side28,30,37and38. In this particular example, the first short side28and first long side37each have an upper lip46extending horizontally outwardly therefrom, forming the edge44and which will be spaced above the earth's surface, or ground,20or other surface. The second short side30and second long side38each have a lower lip54extending horizontally outwardly therefrom below the edge44thereof and which will rest on or near the earth's surface, or ground,20or other surface. The upper and lower lips46,54may have any suitable size, shape, configuration and length. It should be understood, however, that the electrically-conductive cover110of the present disclosure is not limited to use with the above-described embodiments of mats26having upper and/or lower lips46,54. For example, other embodiments of the cover110may be used in connection with mats26not having upper and/or lower lips46,54.

Still referring to the embodiment ofFIG. 3, the respective upper and lower lips46,54of different mats26are interconnectable with locking pins34(e.g.FIGS. 4 & 5) releasably securable through corresponding locking pin holes32formed therein. The locking pin holes32and locking pins34may have any suitable form, construction and configuration. In this embodiment, the illustrated mats26include a plurality of locking pin holes32, each configured to accept a releasable locking pin34(e.g.FIG. 4) therethrough. Each illustrated mat26may include a total of sixteen locking pin holes32, eight formed in each of the upper and lower lips46,54. In some embodiments, the locking pins34may form a fluid-tight seal around, or in, the locking pin holes32within which they are engaged. Some examples of locking pins34which may be used in various embodiments of the present disclosure are shown and described in U.S. Pat. No. 6,722,831 to Rogers et al, entitled “Fastening Device” and issued on Apr. 20, 2004, U.S. Provisional Patent Application Ser. No. 61/748,818, entitled “Apparatus and Methods for Connecting Mats” and filed on Jan. 14, 2013, and U.S. patent application Ser. No. 13/780,350, entitled “Apparatus and Methods for Connecting Mats” and filed on Feb. 28, 2013, all of which have a common Assignee as the present patent and the entire contents of which are hereby incorporated by reference herein in their entireties.

In the illustrated example, the locking pin holes32of the mats26have an oval-shape to accept an oval-shaped enlarged head36(e.g.FIGS. 4 & 5) of the illustrated locking pins34. It should be noted, however, that the present disclosure is not limited to use with the above-described or referenced types and configurations of load-supporting surfaces16, mats26, locking pins34and locking pin holes32, or to the disclosures of the above-referenced patents and patent applications. Any suitable load-supporting surfaces16, mats26, locking pins34and locking pin holes32may be used.

Now referring toFIG. 4, in some embodiments, a gap22may be formed between adjacent edges44of adjacent interconnected mats26in the load-supporting surface16and one or more seal members10may be included therein. For example, the seal member(s)10may provide a fluid-tight seal in the gap22between adjacent mats26to prevent liquid introduced onto the load-supporting surface16from seeping or flowing between and below the load-supporting surface16. Some embodiments of seal members10that may be used in the gaps22are disclosed in U.S. patent application Ser. No. 13/803,580, filed on Mar. 14, 2013 and entitled “Apparatus and Methods for Sealing Between Adjacent Components of a Load-Supporting Surface”, U.S. Provisional Patent Application Ser. No. 62/013,899 filed on Jun. 18, 2014 and entitled “Load-Supporting Surface with Interconnecting Components and Top Side Seal Assembly for Sealing Therebetween and Methods of Assembly and Use Thereof”, U.S. Provisional Patent Application Ser. No. 62/011,805 filed on Jun. 13, 2014 and entitled “Load-Supporting Surface with Interconnecting Components and Frame-Style Seal Assembly for Sealing Therebetween and Methods of Assembly and Use Thereof”, all of which have a common Assignee as the present patent and the entire contents of which are hereby incorporated by reference herein in their entireties. The seal member10may also or instead be used between one or more mat26and one or more other component associated with the load-supporting surface16, and/or between the other components themselves. Some examples of such additional components that may be useful in connection with load-supporting surfaces16, such as berm members, spacers, drive-over barriers, liquid drain assemblies, etc., are shown and disclosed in U.S. patent application Ser. No. 13/790,916, entitled “Liquid Containment System for Use With Load-Supporting Surfaces” and filed on Mar. 8, 2013.

Referring back toFIG. 1, in accordance with the present disclosure, the electrically-conductive cover110may have any suitable form, configuration and operation so that it can be used to allow the load-supporting surface16to be effectively and successfully grounded to the earth or other suitable structure. In the present embodiment, the electrically-conductive cover110includes an outer frame120(see alsoFIGS. 6A-C) and an inner mesh portion126. The frame120and mesh portion126may be constructed of any suitable material and have any suitable configuration that allows the load-supporting surface16to be effectively and successfully grounded to the earth or other suitable structure. For example, the frame120and mesh portion126may be constructed at least partially of aluminum, stainless steel or other electrically-conductive material or a combination thereof. The illustrated frame120is a welded rectangular steel frame providing rigidity for the cover110and preserving its integrity during use, such as when the mat112is driven over by vehicles and machinery. The mesh portion126may be constructed of any suitable at least partially metallic mesh or grating, such as an aluminum mesh configuration that is sufficiently electrically conductive and sufficiently strong and durable to withstand use as part of a load-supporting surface.

In this example, the frame120and mesh portion126are welded together. For example, as shown inFIG. 5, the perimeter edges128of the mesh portion126may be welded to the top122of the frame120. However, the frame120and mesh portion126may be coupled together or interconnected in any other suitable manner.

Referring again toFIG. 1, the illustrated cover110also includes at least one conductive interface138useful to electrically connect the EPZ mat112with one or more adjacent EPZ mat112. The conductive interface(s)138may have any suitable form, configuration and operation. In this embodiment, the cover110has an interface138extending on each side28,30,37and38of the mat26to electrically connect the mat26with a corresponding respective adjacent interconnected mats26(see e.g.FIGS. 2,7-9). For example, the frame120may be used to form an interface138on each side28,30,37and38of the mat26that will abut, and thus electrically contact, an interface138on a respective adjacent interconnected mat26. In the present embodiment, on each side28,37of the mat26having upper lips46, the frame120extends at least partially around the edge44thereof to form an underside face156(FIG. 9) which serves as the conductive interface138along that respective side of the mat26(See alsoFIGS. 8 & 9). On each side30,38of the mat26having lower lips54, the exemplary frame120extends at least partially across the top142of the lower lip54to form an upward face160that serves as the conductive interface138along that respective side of the mat26. As shown inFIGS. 8 & 9, the respective interfaces138of adjacent interconnected EPZ mats112contact one another to form an electrically conductive path therebetween. However, the present disclosure is not limited to the above type and arrangement of interfaces138. For example, there may be interfaces on less than all sides28,30,37and38of the mat26. For another example, the interface(s)138may be disposed at specific locations on one or more sides of28,30,37and38of the mat26and/or at entirely different locations on the cover110.

Referring toFIG. 5, if desired, a conductive booster188may be used in connection with one or more interface138of each mat112, such as to assist in ensuring a good electrical connection between adjacent interconnected mats112. The conductive booster188may have any suitable form, configuration and operation. In the illustrated embodiment, the booster188is a metallic braided band190inserted between the corresponding underside face156(see e.g.FIG. 9) and upward face160of the frames120on a pair of adjacent interconnected EPZ mats112. The band190may, for example, have copper, aluminum or steel braiding and extend between a portion or all of the length of the adjacent faces156,160. In this embodiment, the band190is a copper braided band coupled, such as with rivets198, screws or other connectors, to each upward face160of the frame120along its length. In other embodiments, multiple or few shorter sections of metallic braided band190may be used.

Referring toFIGS. 12A-B, if desired, the mesh portion126may include a cut-out178formed therein over each locking pin hole32. For example, the cut-out178may be useful to electrically isolate a locking pin34(e.g.FIGS. 4 & 5) placed in the locking pin hole32and prevent electrical conductivity between the cover110and the locking pin34. The cut-out178may have any suitable form, configuration and operation. In this example, each cut-out178is spaced away from its corresponding locking pin hole32to ensure sufficient electrical isolation. A cut-out frame180(see alsoFIGS. 6 & 8) constructed of any suitable material, such as one or more compatible metallic material (e.g. aluminum, steel, etc.), is shown connected to, such as by weld, and covering the edges of the mesh portion126that form the cut-out178. The cut-out frame180may, for example, provide stability around the cut-out178and/or protect the exposed mesh portion126on the edges of the cut-out178. However, the cut-out frame180, if included, may be constructed of any other suitable material and connected with the mesh portion126or mat26in any other suitable manner.

At least one interconnected EPZ mat112of a load supporting surface16may be grounded to the earth or other structure in any suitable manner. Referring back toFIG. 1, for example, a metal plate166may be electrically connected, such as by weld, to the cover110. In this embodiment, the plate166is welded atop the mesh portion126and frame120in one corner of the cover110. A grounding cable170is shown electrically connected between the plate166and a grounding rod174that may be driven into the earth for electrically grounding the entire load-supporting surface16. For example, any suitable commercially available grounding cable170and rod174and related components may be used, such as the grounding rod currently having Catalog No. 4370, stringing rod currently having Catalog No. 9738 and hanger studs currently having Catalog Nos. 13190-1 and 13210 currently sold by Hastings Hot Line Tools and Equipment.

In accordance with an embodiment of a method of assembly and use, the exemplary EPZ mat112may be assembled in any suitable manner. For example, referring toFIG. 1, the illustrated frame120and mesh portion126are connected, such as by weld. If desired, the frame120and mesh portion126may be painted with galvanized paint, such as to enhance its electrical conductivity and reduce or prevent corrosion. The exemplary cover110is positioned on the top face or surface132of the mat26. The edges148,150of the illustrated frame120that are aligned with the respective sides28,37of the mat26may be at least partially bent around the edges44thereof. The edges152,154of the illustrated frame120that align with the respective sides30,38of the mat26may be at least partially bent down and out over part of the top142of the respective lower lip54(see alsoFIGS. 10A-B). In other embodiments, one or more of the edges148,150,152,154of the frame120may be at least partially pre-formed or bent into its desired shape (see alsoFIGS. 10A-B) before placement of the cover110onto the mat26.

It should be noted that in other embodiments, the cover110may also or instead extend at least partially across the bottom face or surface (not shown) of the mat26, or may extend across only part of the top surface132of the mat26. Likewise, the frame120may extend across a different portion, or all, of the lower lip54of the sides30,38of the mat26and may, if desired, extend around the edges44thereof. Thus, the present disclosure is not limited to a cover110having a mesh portion126that extends over the entire top surface132of the mat26and a frame120that extends at least partially around the edges44of the sides28,37and across at least a portion of the lower lip54of the sides30,38of the mat26. Any other suitable configuration may be used.

If desired, the frame120and/or mesh portion126may be further coupled to the mat26, such as with one or more connector. For example, referring toFIG. 11, the mesh portion126(e.g.FIG. 1) may be connected, such as by tack weld, to multiple of the bolt heads70accessible at the top surface132of a “bolted” mat26. Bolted mats26are formed, for example, by bolting two mat sections together, such as shown and described in U.S. Pat. No. 6,511,257 to Seaux et al., entitled “Interlocking Mat System for Construction of Load Supporting Surfaces” and issued on Jan. 28, 2003 (e.g.FIG. 6therein).

Referring again toFIG. 1, the booster(s)188and metal grounding plate166, if included on this particular mat112, may be coupled to the cover110, such as described above, in advance or at any desired time after the cover110is coupled to the mat26. If the load-supporting surface16includes multiple EPZ mats112(e.g.FIGS. 2,7), the overlapping lips46,54of adjacent mats26are interconnected using locking pins34(e.g.FIGS. 4 & 5) as described above and in one or more of the patents and patent applications previously incorporated herein by reference. In the referenced embodiments, the exemplary locking pins34accurately position the adjacent mats26relative to one another and firmly interconnect them, avoiding unnecessary rises and falls and helping form a strong electrical connection therebetween.

As shown inFIGS. 7-9, upon interconnection of the illustrated mats112, the interfaces138of adjacent mats112will contact one another to electrically connect them together. Grounding of at least one mat112will electrically ground the series of interconnected mats112in the load-supporting surface16. A low resistivity path is formed between each mat112, allowing the flow electrical charge and limiting the rise of earth potential over the load-supporting surface16. Electrical tests for the exemplary load-supporting surface16have demonstrated that they successful pass the current from one mat112to the next without substantial losses of electrical current or build-up of substantial heat.

After use, the mats112of a multi-mat load-supporting surface16may be disconnected from one another. In the present embodiment, the exemplary cover110of each EPZ mat112may be removed from its corresponding mat26and replaced onto the same or another mat26. For example, if the cover110suffers extensive damage during use, it can be removed, repaired and/or replaced. The mat26may be reused with or without the cover110.

Preferred embodiments of the present disclosure thus offer advantages over the prior art and are well adapted to carry out one or more of the objects of this disclosure. However, the present invention does not require each of the components and acts described above and is in no way limited to the above-described embodiments or methods of operation. Any one or more of the above components, features and processes may be employed in any suitable configuration without inclusion of other such components, features and processes. Moreover, the present invention includes additional features, capabilities, functions, methods, uses and applications that have not been specifically addressed herein but are, or will become, apparent from the description herein, the appended drawings and claims.

The methods that may be described above or claimed herein and any other methods which may fall within the scope of the appended claims can be performed in any desired suitable order and are not necessarily limited to any sequence described herein or as may be listed in the appended claims. Further, the methods of the present invention do not necessarily require use of the particular embodiments shown and described herein, but are equally applicable with any other suitable structure, form and configuration of components.

While exemplary embodiments of the invention have been shown and described, many variations, modifications and/or changes of the system, apparatus and methods of the present invention, such as in the components, details of construction and operation, arrangement of parts and/or methods of use, are possible, contemplated by the patent applicant(s), within the scope of any appended claims, and may be made and used by one of ordinary skill in the art without departing from the spirit or teachings of the invention and scope of this disclosure and any appended claims. Thus, all matter herein set forth or shown in the accompanying drawings should be interpreted as illustrative, and the scope of the disclosure and any appended claims should not be limited to the embodiments described and shown herein.