Abstract:
A bonding clip formed of a metal and having unitary or multi-part construction is used to electronically bond together wires of adjacent wire mesh cable trays. The bonding clip binds the wire mesh cable trays by penetrating the protective coating one the wire mesh cable trays with teeth-like projections in order to permit conductive contact between the wires. The bonding clip has a profile that permits maintenance of the cross-sectional area formed by the wires of the wire mesh cable trays.

Description:
[0001]    This application claims the benefit of U.S. Provisional Patent Application No. 61/085,138, filed on Jul. 31, 2008, the entire disclosure of which is hereby incorporated by reference, in its entirety, as if set forth fully herein. 
     
    
       [0002]    The invention relates generally to cable tray bonding clips and, in particular, to wire mesh cable tray bonding clips. 
         [0003]    Generally, a cable tray system is a rigid structural support system used to mechanically support cables and wires across open spans. One type of cable tray is a wire mesh cable tray. Typically, wire mesh cable trays are used at a job site for field adaptable support systems for low voltage, telecommunication and fiber-optics cables and are installed on short support spans between about four to about eight feet. 
         [0004]    Wire mesh cable trays are formed by a wire structure, generally of metal. They comprise longitudinal wires known as “warp” wires, that run longitudinally, and transverse wires known as “weft” wires, that run perpendicular to the warp wires. The warp and weft wires are welded or otherwise permanently connected to one another at their points of contact to form a U-shaped tray having a bottom and two lateral sides in which the upper parts of the sides terminate in a longitudinal edge wire and the ends of each tray may terminate in a substantially U-shaped edge wire or wires, and, in some embodiments, individual longitudinal wires along the sides and bottom of a tray may extend beyond the terminal transverse edge wire at one or both of the tray ends. Wire mesh cable trays have standard widths of 2, 4, 6, 8, 12, 16, 18, 20 and 24 inches, standard depths of 1, 2 and 4 inches, and a standard length of about 118 inches. 
         [0005]    Typically, wire mesh cable trays are interconnected in series in an end to end configuration. In some embodiments, the terminal transverse edge wires at the tray ends are interconnected, while in other embodiments, the interconnections are made between the terminal transverse edge wires and one or more of terminal extending longitudinal wires, or both. The intersections between adjacent wire mesh cable trays are created manually on the job when a cable tray run is assembled for use and affixed to a building structure, using an array of different brackets and clamps that are known in the art. In some instances, wire cutters are used to adjust or correct for any undesirable wire overlap. A series of two or more wire mesh cable trays can be installed in any possible position over a given length of run, wherein the positions of each span of cable tray may be parallel, perpendicular or at an angle relative to a fixed building structural feature such as a wall, ceiling or floor. 
         [0006]    Wire mesh cable tray units are typically formed of steel wire mesh that is zinc plated, or otherwise treated or coated to render a surface that is resistant to corrosion and is not electrically conductive. In some common embodiments, wire mesh cable trays are first formed from steel and then hot dipped, or coated, by galvanization. Current applicable codes, including the National Electric Code (“NEC”), require that all wire mesh cable trays be conductively connected for purposes of grounding. These code requirements impose the need for the presence of an Equipment Ground Conductor with industry standard ground fault protections of specific ampere ratings. In some circumstances, cable trays may be used as Equipment Ground Conductors if they meet the NEC and/or other applicable industry and regulatory requirements. Moreover, NEC and other applicable industry and regulatory requirements establish a minimum cross sectional area of metal that must be in contact between adjacent cable trays in order to meet the Equipment Ground Conductor requirements. 
         [0007]    Conventional brackets and clamps used for connecting wire mesh cable tray units typically encase the coated wires and do not provide electrical connectivity between the units. Indeed, in many instances, such connecting brackets and clamps further impede electrical connectivity between the units. Thus, the devices known and used in the art are not sufficient for fulfilling the desirable function of enabling electrical conductivity along runs of wire mesh cable tray systems. Therefore, there is a need for a suitable connector for wire mesh cable trays that ensures a stable mechanical union between adjacent trays and also enables electrical connectivity between adjacent wire mesh cable tray units and along complete cable tray runs. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    In various embodiments, the invention provides bonding clips for interconnection of wire mesh cable trays to enable the assembly of a run of wire mesh cable tray units that conforms to the rigorous code requirement of continuous grounding. The bonding clips affix to and encase the weft wires of adjacent wire mesh cable tray units, retaining the units in stable and non-pivotal contact while rendering the contact surfaces of the encased weft wires at least partially free of any protective coating so as to permit conductivity between the adjacent wire mesh cable tray units. Thus, in various embodiments, the bonding clips enable the assembly of wire mesh cable tray runs that are electrically conductive at the points of contact between adjacent wire mesh cable tray units to ensure proper grounding. 
         [0009]    The bonding clips are configured to be positioned on the weft wires at any of the areas between the longitudinal warp wires along any of the side and the bottom portions of the U-shaped form of adjacent wire mesh cable tray units. The bonding clips have an essentially flat profile such that when affixed to weft wires of adjacent cable trays, the bonding clips fit within the cross sectional area of the side or bottom portion to which they are affixed, and do not extend into the gutter space; thus, the bonding clips do not appreciably alter the cross-sectional area of metal at the interface between adjacent tray units, and they do not extend within the gutter space so as to not interfere with any cables that may be placed therein when the assembled wire mesh cable tray run is in use. 
         [0010]    The bonding clips of the invention are configured to encase a portion of the weft wires of adjacent wire mesh cable tray units at a position along either of the sides or the bottom of the U-shaped form. The bonding clips have opposing faces, each with an interior wire contact surface, and each with an external tray surface, and contact and affix to the weft wires of adjacent cable trays to surround and encase contacted surfaces of the wires. At least one of each of the opposing interior wire contact surfaces of the bonding clips is formed with a plurality of teeth-like projections and the opposing interior wire contact surfaces, when positioned on the wires, are configured for opposing interaction such that the teeth-like projections penetrate and partially strip any protective coating on the surface of the encased wires. 
         [0011]    The bonding clips are fixed in place with one or more fastener elements, and in some embodiments the bonding clips or the one or more fastener elements can include a grounding lug for use in large ampere applications. In various embodiments, the bonding clips comprise on at least their external tray surfaces anti-corrosive treatment or coating such that the cable tray runs assembled with the bonding clips retain an overall surface property that is resistant to corrosion and electrical conductivity. 
         [0012]    Other features of the embodiments of the present invention will be apparent in light of the description of the invention embodied herein. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0013]    The following detailed description of specific embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which: 
           [0014]      FIG. 1A  illustrates a cable tray known in the art; 
           [0015]      FIG. 1B  illustrates alternative views of a bonding clip according to an embodiment of the present invention affixed and joining two adjacent wire mesh cable tray units, wherein the bonding clip is affixed between longitudinal wires along one of the side walls of the tray system; 
           [0016]      FIG. 2  illustrates in five panels alternate embodiments of the bonding clip; 
           [0017]      FIG. 3  illustrates three perspectives of the bonding clip embodiment of  FIG. 2A ; 
           [0018]      FIG. 4  illustrates three perspectives of the bonding clip embodiment of  FIG. 2B ; 
           [0019]      FIG. 5  illustrates three perspectives of the bonding clip embodiment of  FIG. 2C ; and 
           [0020]      FIG. 6  illustrates an embodiment of a grounding lug. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    In the following detailed description of the embodiments, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration, and not by way of limitation, specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and that logical, mechanical and electrical changes may be made without departing from the spirit and scope of the present invention. 
         [0022]    The invention provides bonding clips for interconnection of wire mesh cable trays to enable the assembly of a run of wire mesh cable tray units that conforms to the rigorous code requirement of continuous grounding. The bonding clips affix to and encase the weft wires of adjacent wire mesh cable tray units, retaining the units in stable and non-pivotal contact while rendering the contact surfaces of the encased weft wires at least partially free of any protective coating so as to permit conductivity between the adjacent wire mesh cable tray units. Thus, in various embodiments, the bonding clips enable the assembly of wire mesh cable tray runs that are electrically conductive at the points of contact between adjacent wire mesh cable tray units to ensure proper grounding. 
         [0023]    As shown in  FIG. 1A , a wire mesh cable tray unit  100  is comprised of longitudinal wires, also known as “warp” wires, that run longitudinally, and transverse wires, also called “weft” wires, that run perpendicular to the warp wires, wherein the warp and weft wires are welded or otherwise permanently connected to one another to form a U-shaped tray. A unit  100  may be of any suitable length, and adjacent units (not shown) may be connected to each other during assembly on the job site by cutting off wire segments, as necessary, and clamping the units together. 
         [0024]    The illustrated tray unit has one form of design that varies from other trays in that the tray units ends terminate in a substantially U-shape, and wherein one end has a single transverse edge wire, while the other end has a pair of transverse edge wires. In addition, according to the depicted cable tray unit, an array of individual longitudinal wires extend beyond the transverse edge wires along the sides and bottom each unit. The wire mesh cable tray units are thus adapted for overlapping between the a singled transverse edge wire end of one unit and the double transverse edge wire end of a second unit so that the transverse edge wires and the extended longitudinal wires interfit to achieve a quick snap locking joint. Of course it will be understood that the illustrated cable tray unit is suitable for use with the connector clips of the instant invention; however, other wire mesh cable tray configurations are known in the art, and thus, other cable trays may be utilized. For purposes of the description and examples provided herein, reference to cable trays will include all possible cable tray configurations, though the illustrated cable trays will be of the configuration as shown in  FIG. 1A . 
         [0025]    Referring now to  FIG. 2 , panels A, B, C, D and E each show alternate embodiments of the bonding clip  200  of the instant invention. Generally, a bonding clip  200  is configured to be positioned on the weft wires of a wire mesh cable tray unit  100  at any of the areas between the longitudinal warp wires along any of the side and the bottom portions of the U-shaped form of adjacent wire mesh cable tray units  140  (see indicated optional positions for attachment between tray units). 
         [0026]    Referring now to  FIG. 1B , two views of an assembly of two wire mesh cable tray units are shown with a bonding clip  200  affixed to the side portion of a tray unit  100 . The upper panel of  FIG. 1B  shows a view of the affixed bonding clip  200  from an interior perspective of the tray assembly, and the lower panel shows a view of the affixed bonding clip  200  from an exterior perspective of the tray assembly. As can be readily seen, the bonding clip  200  has an essentially flat profile, such that when affixed to weft wires of adjacent cable trays, the bonding clip  200  fits within the cross sectional area of the side or bottom portion to which it is affixed. As can also be seen, the bonding clip  200  does not extend into the gutter space and will, thus, not interfere with any cables that may be placed therein when the assembled wire mesh cable tray run is in use. The profile of the bonding clip  200  is thus desirable in that it also reduces the possibility that any cable positioned in the tray that may pass over an intersection between try units will catch or snag on a bonding clip  200 . 
         [0027]    Referring again to  FIG. 2 , each depicted bonding clip  200  is configured to encase a portion of the weft wires of adjacent wire mesh cable tray units. The bonding clip  200  can be formed of one piece mounting, according to the alternate embodiments shown in  FIG. 2A ,  FIG. 2   b  and  FIG. 2C . In yet other embodiments, the bonding clip  200  can be formed of two, three or more pieces.  FIG. 2D  and  FIG. 2E  show alternate views of an embodiment of the bonding clip  200 , wherein the bonding clip  200  is formed of two pieces. It will be readily apparent to one of skill in the art that construction of the alternate embodiments can be achieved by a variety of means, including, but not limited to casting or stamping. 
         [0028]    Referring again to the alternate embodiments shown in  FIG. 2A ,  FIG. 2   b  and  FIG. 2C , the depicted bonding clips  200  are of unitary construction, and are formed into a clamp shape having two opposing arms  220  and  240  that define between them an elongated slot. Each arm  220  and  240  of a bonding clip  200  has opposing interior faces with a wire receiving portion  280  for contacting and retaining inserted wires by compression between the opposing arms  220  and  240  and with a fixation portion  290  for receiving a fastener to lock the bonding clip  200  into compressive engagement with the wires of adjacent wire mesh cable tray units. Each arm  220  and  240  of a bonding clip  200  also has an external tray surface. The bonding clip  200  can be used on most any type of wire mesh cable tray, and one of ordinary skill in the art would appreciate that the bonding clip  200  could be adapted to retain wires of wire mesh trays having wire diameters that are known and commonly used in the art. 
         [0029]    In use, a bonding clip  200  is slipped over adjacent weft wires of adjacent tray units such that the adjacent wires are in at least partial contact with one another and are positioned within the wire receiving portion  280  of the elongated slot  260 . When the opposing arms  220  and  240  are moved toward one another, they contact a portion of the surfaces of the wires and by compression affix to the weft wires of adjacent cable trays to surround and encase contacted surfaces of the wires. 
         [0030]    At least one of each of the opposing interior faces of the arms  220  and  240  of a bonding clip  200  has a plurality of teeth-like projections  300  in the receiving portion  280 . When the bonding clip  200  is positioned on the wires of the adjacent tray units and compressive force is applied to move the arms  220  and  240  together, the opposing interaction between the arms  220  and  240  causes the teeth-like projections  300  to penetrate and partially strip any protective coating on at least a portion of the surface of the wires encased within the receiving portion  280 . 
         [0031]    In use, the bonding clip  200  is configured with the teeth-like projections  300  to penetrate through the galvanized coating of the wires of the wire mesh cable trays to thereby form a physical connection between the untreated metal of the wire mesh of each tray unit and the bonding clip  200 . This compressive attachment and contact provides for a stable and not-pivotal connection between the wire mesh cable tray units, and for embodiments wherein a conductive connection is desirable, the direct contact between the encased wires and the bonding clip  200  effectively jumpers the two wire mesh cable trays together. 
         [0032]    According to various embodiments, bonding clips  200  may be secured in a closed configuration and fixed in place with one or more fastener elements. According to one such embodiment, a bonding clip  200  can be bolted into place using a standard bolt and locking nut according to fasteners well known in the art.  FIG. 2 , panels A, B, C and D each show alternate embodiments of the bonding clip  200  with a stud or bolt inserted through one of corresponding receiving apertures in the fixation portion  290  of the opposing arms  220  and  240 .  FIG. 1B  illustrates the bonding clip  200  fully attached and bonded to a couple of wire mesh cable trays. It will be readily appreciated that a very wide variety of fasteners are known and can be used to secure the bonding clip  200 , and that receiving structures on the bonding clip  200  may be introduced so as to permit attachment of the fasteners therewith. Examples of alternate fasteners include, but are not limited to, any of a variety of clips, rivets, sockets, ties, rings, keys, hoks, screws, bolts, and pins, and other suitable fasteners known in the art. 
         [0033]    In some embodiments the bonding clips  200  or the one or more fastener elements, or combinations thereof, can include a grounding element or device, such as a grounding lug, which may be particularly useful for large ampere applications. 
         [0034]    In various embodiments, the bonding clips  200  comprise on at least their external surfaces one or more anti-corrosive treatments or coatings such that the cable tray runs assembled with the bonding clips retain an overall surface property that is resistant to corrosion and electrical conductivity, while in some embodiments thereof the interior contact surfaces of the receiving portions  280  of the bonding clips  200  permit conductivity therewith and between affixed adjacent wire mesh cable tray units. 
         [0035]    The bonding clip  200  can be comprised of metal, such as, for example, steel, or any other suitable conductive or non-conductive material. For purposes of providing cable tray systems that can serve as Equipment Grounding Conductors, the wire mesh cable tray units are comprised of conductive materials. 
         [0036]    Thus, referring again to  FIG. 2 , the illustrated alternate embodiments of the bonding clip include the embodiment shown in  FIG. 2A  which has a recessed receiving portion and an fastening portion with a tab on each arm having apertures therethrough and bolt inserted through the aperture of one arm, and a set of teeth-like structures on one arm and extending within the receiving portion.  FIG. 3  provides further views of the bonding clip embodiment of  FIG. 2A . 
         [0037]    The embodiment shown in  FIG. 2B  has a recessed receiving portion and a fastening portion with a tab on each arm having alternately shaped apertures therethrough and bolt inserted through the aperture of one arm, and a opposing sets of teeth-like structures on each arm extending within the receiving portion.  FIG. 4  provides further views of the bonding clip embodiment of  FIG. 2B . 
         [0038]    The embodiment shown in  FIG. 2C  has a recessed receiving portion and a fastening portion with a tab on each arm having alternately shaped apertures therethrough and bolt inserted through the aperture of one arm, and a set of teeth-like structures on one arm, the teeth-like structures having a curvature from one end to the other such that the centermost teeth-like structures extending farther within the receiving portion than those on the ends.  FIG. 5  provides further views of the bonding clip embodiment of  FIG. 2C . 
         [0039]    And the embodiment shown in  FIG. 2D  and  FIG. 2E  has arms that are formed of two separate parts and are hingedly connected, and having a receiving portion and a fastening portion on one arm that are coplanar and a receiving portion and fasting portion on the other arm that are not coplanar and a tab on each arm having alternately shaped apertures therethrough and bolt positioned for insertion through the aperture as shown in  FIG. 2E , and wherein the arms each comprise opposing sets of teeth-like structures on each arm that extend within the receiving portion. 
         [0040]    The dimensions of the various bonding clips of the instant invention are readily adaptable to accommodate wires of the various known and standard wire mesh cable tray units, and it would be clear to one of ordinary skill that the specific longitudinal dimensions, as well as the thicknesses and widths of the bonding clips could be varied so long as they would be capable of engagement with known and standard wire mesh trays. Likewise, it would be clear that the specific shape and number of apertures formed within the fastening portions of the bonding clips could be varied so as to accommodate known and standard fasteners of varying sizes. And further, the number and shapes of the teeth-like structures could be varied. According to what is known in the art regarding such structures so long as the teeth-like structures are sufficient in rigidity to scrape or pierce the coatings on mesh wires. 
       Examples 
       [0041]    In one embodiment, a bonding clip  200  can have any overall length of about 1.72 inches (or about 43.72 mm), an overall width of about 0.98 inches (or about 24.81 mm). 
         [0042]    In another embodiment, a bonding clip  200  can have two apertures on its external surface and an overall length of about 1.722 inches (or about 43.73 mm), and an overall width of about 0.977 inches (or about 24.81 mm). 
         [0043]    In yet another embodiment, a bonding clip  200  can have three apertures on its external surface, an overall length of about 1.7 inches (or about 43.72 mm), and an overall width of about 0.98 inches (or about 24.81 mm). 
         [0044]    In still another embodiment, a bonding clip  200  can provide a threaded stud to hold a grounding lug, as shown in  FIG. 6  which then can be used to allow the wire mesh cable tray to be used for large ampere applications as defined in section  392  of the National Electrical code Table 392.7(B). In one embodiment, the grounding lug can be hexagonal in shape and can have a diameter of about 0.94 inches (or about 23.88 mm) with an interior diameter of about 0.236 inches (or 6 mm) with an height of about 1.02 inches (or about 26 mm) as illustrated in  FIG. 6A . 
         [0045]    In another embodiment, the grounding lug can be hexagonal in shape and can have a diameter of about 0.815 inches (or about 20.70 mm) with an interior diameter of about 0.236 inches (or 6 mm) with an height of about 0.883 inches (or about 22.45 mm) as illustrated in  FIG. 6B . 
         [0046]    In still another embodiment, a bonding clip  200  can have any overall length of about 1.87 inches (or about 47.6 mm), an overall width of about 0.98 inches (or about 24.8 mm). 
         [0047]    Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for describing particular embodiments only and is not intended to be limiting of the invention. As used in the description of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. All publications, patent applications, patents, and other references mentioned herein are expressly incorporated by reference in their entirety. 
         [0048]    Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding approaches. 
         [0049]    Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Every numerical range given throughout this specification will include every narrower numerical range that falls within such broader numerical range, as if such narrower numerical ranges were all expressly written herein. 
         [0050]    Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.