Abstract:
An adjustable ground clamp for easy positioning onto electric conduits of different diameters and grounding multiple electrical devices. A first and a second jaw are pivotally connected and have differently angled jaw surfaces. A distal end of the first jaw has an elongated hole and a distal end of the second jaw has a curved fork having a slot for receiving a bolt with a cylindrical nut. A fastener connects a ground conductor or wire to the ground clamp. A terminal block accepts ground conductors from multiple different electrical devices. The jaws may be easily separated for placement of an electrical conduit without separating or detaching any parts from the ground clamp, making attachment to an electrical conduit quick, easy, and secure. The terminal block permits different electrical devices to be grounded with a single ground clamp.

Description:
RELATED APPLICATION 
       [0001]    This application is a continuation-in-part of application Ser. No. 12/899,705 filed Oct. 7, 2010. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates in general to an electric ground clamp for attaching to an electrical conduit, and more particularly to an adjustable clamp that is easily and quickly installed and that provides multiple grounding connections. 
       BACKGROUND OF THE INVENTION 
       [0003]    In many electrical applications, it is often necessary to electrically ground a conduit. Often a ground clamp is attached to the conduit. A ground conductor or wire is then attached or connected to the ground clamp providing continuity or an electrical path to ground. Typically a compression clamp is used that often has two opposing screws or fasteners that are alternately tightened to draw two opposing sections of the clamp together substantially equally, so as to clamp down on the electrical conduit. 
         [0004]    One such ground clamp is disclosed in U.S. Pat. No. Des. 243,404 entitled “Ground Clamp” and issuing to Mooney et al on Feb. 15, 1977. Therein disclosed is a ground clamp having opposing portions, with a screw or a fastener on each end. The ground clamp is tightened on the conduit by alternately tightening each screw on the opposing ends. 
         [0005]    Another ground clamp is disclosed in U.S. Pat. No. 3,892,455 entitled “Ground Clamp Connector” and issuing to Sotolongo on Jul. 1, 1975. Therein disclosed is a standard ground clamp connector having a single intermediately positioned fastener for drawing two opposing body portions together. Additional nests are provided in the body portion to accept multiple ground conductors or wires. 
         [0006]    Another ground clamp is disclosed in U.S. Pat. No. 3,985,411 entitled “Hinged Ground Clamp” and issuing to Mooney et al on Oct. 12, 1976. Therein disclosed is an electrical conduit grounding assembly and a pair of longitudinal extending dihedral angle clamp members which embrace the conduit with a hinged knuckle along a proximal longitudinal edge engaging the grounding cable. A screw on the distal end of the clamp members is used to tighten the ground clamp onto the electrical conduit. 
         [0007]    While these prior ground clamps have been used successfully to ground electrical conduits, they are often difficult to install and often require disassembly of the ground clamp resulting in loose parts which may be lost. Additionally, often different sized conduits must be accommodated that are often in difficult to reach locations. Therefore, it may be difficult to disassemble and then reassemble a ground clamp around an electrical conduit in difficult to reach locations without loosing or dropping a part of the ground clamp. This makes installation frustrating and difficult. Therefore there is a need for a ground clamp that will accommodate a wide range of different sized conduits, and that is easy to install without the need of removing a part of the ground clamp which could be dropped or lost. 
         [0008]    In some applications multiple electrical devices must be grounded. This often requires multiple ground clamps to be attached to a single pipe or rigid conduit. The attaching of multiple ground clamps may be difficult due to limited space. Additionally, poor electrical contact may be made when ground clamps are subsequently installed, especially if after placement of a first ground claim the pipe or rigid conduit has been painted or has become dirty or oxidized. Therefore, there is an additional need for a ground clamp that can accommodate the grounding of multiple electrical devices without removal of the ground clamp or placement of additional ground clamps. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention comprises a first and a second hinged jaw with predetermined angled surfaces to securely grip a wide range of electrical conduit sizes or diameters. The first jaw has a distal end with an elongated hole holding a bolt. The second jaw has a distal end with a curved fork having a slot. The curved fork has a surface that accommodates or mates with a cylindrical nut threaded on to the bolt held by the elongated hole in the distal end of the first jaw. The slot of the curved fork receives the bolt used in securing the distal ends of the first and second hinged jaws. The predetermined angled surfaces of the hinged jaws have different angles for securely holding a wide range of different electrical conduit diameters. Means for connecting a ground conductor or wire to the ground clamp is provided on one of the first or second hinged jaws. 
         [0010]    In another embodiment a terminal block is formed on one of the jaws of the ground clamp. The terminal block has a plurality of ground conductor connection locations. A plurality of holes is formed in the terminal block through which multiple ground conductors may be placed. A screw intersects with the hole so that the ground conductors placed therein can be securely locked or held in position. 
         [0011]    Accordingly it is an object of the present invention to provide a ground clamp that is easily installed onto a wide range of different sized electrical conduits. 
         [0012]    It is another object of the present invention to prevent the possible loss of a fastener or screw used with the ground clamp when attaching the ground clamp to an electrical conduit. 
         [0013]    It is an advantage of the invention that it can be securely fastened to different electrical conduits with a range of different sizes or diameters. 
         [0014]    It is an advantage of the invention that a single fastener, bolt, or screw is used. 
         [0015]    It is yet another advantage of the invention that the grounding clamp can be fitted over and tightened to an electrical conduit without any disassembly resulting in loose or separated parts that could be lost. 
         [0016]    It is a feature of the invention that an elongated hole is formed on a distal end of the first hinged jaw. 
         [0017]    It is another feature of the invention that a curved fork having a slot is formed on the distal end of an opposing hinged jaw with the curved fork shaped to receive a cylindrical nut. 
         [0018]    It is yet another feature of the present invention that the first and second hinged jaws have different angled surfaces adapted to accommodate the different sizes or diameters of a wide variety of electrical conduits. 
         [0019]    It is yet another object on an embodiment of the present invention to permit multiple electrical devices to be grounded on a single ground clamp. 
         [0020]    It is an advantage of an embodiment of the present invention that multiple grounding clamps do not have to be used for grounding multiple electrical devices. 
         [0021]    It is a feature of an embodiment of the present invention that a terminal block is placed on a jaw of a ground clamp. 
         [0022]    These and other objects, advantages, and features will become more readily apparent in view of the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  is an elevational view of an embodiment of the invention holding a larger diameter electrical conduit. 
           [0024]      FIG. 2  is a perspective view of an embodiment of the invention holding a larger diameter electrical conduit. 
           [0025]      FIG. 3  is an elevational view of an embodiment of the invention holding a smaller diameter electrical conduit. 
           [0026]      FIG. 4  is a perspective view of an embodiment of the invention holding a smaller diameter electrical conduit. 
           [0027]      FIG. 5  is a plan view of an embodiment of the invention. 
           [0028]      FIG. 6  is an exploded view of an embodiment of the invention. 
           [0029]      FIG. 7A  schematically illustrates the angled surfaces of a first jaw of an embodiment of the invention. 
           [0030]      FIG. 7B  schematically illustrates the angled surfaces of a second jaw of an embodiment of the invention. 
           [0031]      FIG. 8  is an exploded view of another embodiment of the invention utilizing a lug mount for attaching a ground conductor or a wire. 
           [0032]      FIG. 9  is an exploded view of another embodiment of the invention utilizing a pad mount for attaching a ground conductor or a wire. 
           [0033]      FIG. 10  is a perspective view of an embodiment of the invention having a terminal block. 
           [0034]      FIG. 11  is a front elevational view of the embodiment illustrated in  FIG. 10 . 
           [0035]      FIG. 12  is a side elevational view of the embodiment illustrated in  FIG. 10 . 
           [0036]      FIG. 13  is an exploded view of the embodiment illustrated in  FIG. 10 . 
           [0037]      FIG. 14  is a perspective view of another embodiment of the invention having a terminal block. 
           [0038]      FIG. 15  is a perspective view of yet another embodiment of the invention having a terminal block. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0039]      FIGS. 1-7B  illustrate a first embodiment of the invention. In  FIG. 1  the ground clamp  10  comprises a first jaw  12  coupled to a second jaw  14  by a hinge  16  and a hinge pin  18 . The first jaw  12  has a first distal end  20  having an elongated hole  22  therein. The second jaw  14  has a second distal end forming a curve having a slot  26  formed therein forming a curved fork  24 . A cylindrical nut  26  has a diameter substantially matching the curve or radius of the curved fork  24  formed on to the second distal end of the second jaw  14 . The cylindrical nut  28  is held on the threaded portion or end  33  of bolt  30  having a head  31 . The head  31  of the bolt  30  retains the bolt  30  within the elongated hole  22 . The conduit  32 , which may be electrical metallic tubing or EMT or a rigid conduit, is held between the first and second jaws  12  and  14 . The first jaw  12  has a first inside angled jaw surface  34  and a first outside angled jaw surface  36  separated by a first intermediate surface  35 . The second jaw  14  has a second inside angled jaw surface  38  and a second outside angled jaw surface  40  separated by a second intermediate surface  39 . Attached to the first jaw  12  are a stem  42  and a lip  44  forming an opening in which to drop in a ground conductor or wire  50 . The stem  42  has a threaded hole  46  for receiving screw  48 . The grounding clamp  10  of the invention is made of a conductive material, preferable a metal. The grounding clamp  10  may be made of extruded aluminum, die cast zinc, cast bronze, cast brass, or zinc plated steel. 
         [0040]      FIG. 2  more clearly illustrates the cylindrical nut  28  having a diameter and the mating with the curve or radius of the curved fork  24  on the distal end of the second jaw  14 . Additionally, the slot  26  forming the curved fork  24  is more clearly illustrated. The slot  26  has a width for receiving the threaded portion of the bolt  30 . Also, the elongated hole on the first distal end  20  of the first jaw  12  is better illustrated. 
         [0041]      FIGS. 3 and 4  illustrate the ability of the ground clamp  10  of the invention to accommodate a wide variety or range of sizes of electrical conduits. A larger conduit  32  is illustrated in  FIGS. 1 and 2 , and a smaller conduit  32 ′ is illustrated in  FIGS. 3 and 4 .  FIGS. 3 and 4  illustrate the ground clamp  10  adjusted to hold a smaller diameter electrical conduit  32 ′. The different angled jaw surfaces  34 ,  36 ,  38 , and  40  in combination with the intermediate surfaces  35  and  39  securely hold different size electrical conduits  32 , illustrated in  FIGS. 1 and 2 , or  32 ′ illustrated in  FIGS. 3 and 4 . 
         [0042]      FIG. 5  is a plan view more clearly illustrating the electrical conduit  32  held within the first jaw  12  of the ground clamp  10 . The ground conduit or wire  50  is also more clearly illustrated being held by stem  42  and screw  48 . 
         [0043]      FIG. 6  is an exploded view of the embodiment of the invention illustrated in  FIGS. 1-5 .  FIG. 6  more clearly illustrates the parts and assembly of the invention. The hinge  16  and the hinge pin hole  52  as well as the hinge pin  18  are more clearly illustrated. Additionally the cylindrical nut hole  54  that receives the threaded portion or end  33  of the bolt  30  is more clearly illustrated. 
         [0044]      FIG. 7A  more clearly illustrates the angled jaw surfaces of the first jaw  12 . The first inside angled jaw surface  34  is positioned in a plane that is substantially 45° from a horizontal reference line  56 . The first outside angled jaw surface  36  is positioned in a plane that is substantially 60° from a horizontal reference line  56 . The first intermediate surface  35  between the first inside angled jaw surface  34  and the first outside angled jaw surface  36  is in a plane substantially perpendicular to the horizontal reference line  56 . The angle between the first inside angled jaw surface  34  and the first outside angled jaw surface  36  is therefore preferably substantially 105°. Additionally, the angle between the first inside angled jaw surface  34  and the first intermediate surface  35  is preferably substantially 135° and the angle between the first outside angled jaw surface  36  and the first intermediate surface  35  is preferably substantially 150°. 
         [0045]      FIG. 7B  schematically illustrates the angular relationship of the second inside angled jaw surface  38  and second outside angled jaw surface  40  of the second jaw  14 . The second inside angled jaw surface  38  is positioned in a plane that is preferably substantially 45° from a horizontal reference line  56 . The second outside angled jaw surface  40  is positioned in a plane that is preferably substantially 60° from a horizontal reference line  56 . The second intermediate surface  39  between the second inside angled jaw surface  38  and the second outside angled jaw surface  40  is in a plane preferably substantially perpendicular to the horizontal reference line  56 . The angle between the second inside angled jaw surface  38  and the second outside angled jaw surface  40  is therefore preferably substantially 105°. Additionally, the angle between the second inside angled jaw surface  38  and the second intermediate surface  39  is preferably substantially 135° and the angle between the second outside angled jaw surface  40  and the second intermediate surface  35  is preferably substantially 150°. 
         [0046]    Accordingly, in both the first and second jaws  12  and  14  the first and second inside angled jaw surfaces  34  and  38  are positioned at a different angle relative to a horizontal reference line  56  than the first and second outside angled jaw surfaces  36  and  40 . These different relative angles permit the first and the second jaws  12  and  14  to securely grip a wide range of different size or diameter electrical conduits. These angular relationships of the jaw surfaces  34 ,  35 ,  36 ,  38 ,  39 , and  40  of the first and second jaws  12  and  14  allows the ground clamp to be attached to different electrical conduit having a range of sizes. In a preferred embodiment the difference in angles accommodates different electrical conduit ranging from approximately 0.700 to 1.32 inches or 1.78 to 3.35 cm in diameter. Therefore the ground clamp can securely hold a standard electrical metallic tube from one-half to one inch and a standard rigid conduit from one-half to one inch. However, it should be appreciated that the ground clamp of the invention may be rescaled to securely hold different sized conduits within a broad range. 
         [0047]      FIG. 8  is an exploded view of another embodiment of the invention. In this embodiment, a different means for attaching a ground conductor is illustrated. The ground clamp  110  has a lug or mound  142  having a ground conductor through hole  144 . Placed within the lug or mound  142  is a threaded hole  146  for receiving the screw  48 . A ground conductor or a wire, not shown, placed within the ground conductor or wire through hole  144  is securely held in place by tightening screw  48  down thereon. 
         [0048]      FIG. 9  is an exploded view of another embodiment of the invention. The ground clamp  210  in this embodiment has a pad  242  having a threaded hole  246  therein. The screw  48  threads within the threaded hole  246 . Therefore, a ground conductor or wire, not shown, wrapped around or placed under screw  48  may be securely held by tightening screw  48  within the threaded hole  246  and securing the ground conductor or wire adjacent the pad  242 . 
         [0049]    As illustrated in the figures and in particular in  FIGS. 1 to 4 , the ground clamp  10  can easily be adjusted to accommodate electrical conduits  32  and  32 ′ of substantially different diameters. Additionally, the ground clamp  10  can easily be adjusted without disassembling or separating any parts of the ground clamp which may be lost or dropped during attachment to an electrical conduit. The combination of the cylindrical nut  28  and the slot  26  in the curved fork  24  permits the second jaw  14  to pivot downward, providing a substantial and large space between the first and second jaws  12  and  14 . After insertion of the electrical conduit  32  or  32 ′ head  31  may be turned causing the cylindrical nut  28  placed adjacent the curved fork  24  to draw the first and second jaws together so that the angled jaw surfaces  34 ,  36 ,  38  and  40  securely hold the electrical conduit  32  or  32 ′. The elongated hole  22  formed in the first distal end of the first jaw  12  permits some movement of the bold  30  maintaining alignment when different size electrical conduits are held. The cylindrical nut  28  and curved fork  24  permits the bolt  30  to pivot so as to accommodate and securely hold a wide range of different sized electrical conduits. 
         [0050]    The present invention, by providing a unique combination of angled jaw surfaces  34 ,  36 ,  38  and  40  in combination with the bolt  30  having a cylindrical nut  28  and curved fork  24  provides an improved electric ground clamp that can securely hold different sized or diameters of electrical conduits and that can be assembled quickly and easily without disassembly of any portion of the ground clamp. The electric ground clamp can easily be placed in hard to reach locations without difficult manipulation. 
         [0051]      FIGS. 10-13  illustrate another embodiment of the invention. In this embodiment a terminal block  358  is formed on the first jaw  12  of the ground clamp  310 . In this embodiment the terminal block  358  permits multiple electrical devices to be grounded on a single ground clamp  310 . The ground clamp  310  comprises a first jaw  12  and a second jaw  14  connected by a hinge  16  and hinge pin  18 . The first jaw  12  has a first distal end  320  with an elongated hole  322  therein and a flat portion  321 . The first jaw  12  has a first inside angled jaw surface  34 , first intermediate surface  35 , and first outside angled surface  36 . The second jaw  14  has second distal end with a curved fork  24 , a second inside angled jaw surface  38 , second intermediate surface  39 , and second outside angled surface  40 . The first and second jaws  12  and  14  are drawn together by bolt  330  having head  331  and cylindrical nut  28 . The first jaw  12  has an opening formed by lip  344  and stem  342 . Screw  348  is used to hold ground conductor or wire  50  securely therein. When closed the first and second jaws  12  and  14  securely hold pipe or rigid conduit  32  therein. 
         [0052]    The ground clamp  310  has terminal block  358  formed thereon. The terminal block  358  has a plurality of holes  360  therein. The holes  360  are adapted to receive conductors  362  from ground wires  364 . The ground wires  364  are coupled to other electrical devices that may need to be grounded, such as phone, data, or cable TV. Screws  366  are placed within threaded holes  368 , illustrated in  FIG. 13 , to securely hold the conductors  362 . Therefore, a plurality of electrical devices, not illustrated, may be grounded with a single ground clamp  310 . While four holes  360  for receiving conductors  362  have been illustrated any number of holes  360  may be used. 
         [0053]      FIG. 14  illustrates another embodiment of a ground clamp. This embodiment is similar to the embodiment illustrated in  FIGS. 10-13 , however in this embodiment a different means for attaching ground conductor  50  is illustrated. The ground clamp  410  has a mound  442  formed within the first jaw  12  and terminal block  458 . A hole  444  is placed in the mound  442  for receiving the ground conductor  50 . Screw  348  is threaded into a threaded hole intersecting with the hole  444  so as to contact the ground conductor  50  placed therein and securely hold it in position. 
         [0054]      FIG. 15  illustrates yet another embodiment of a ground clamp. This embodiment is similar to the embodiment illustrated in  FIGS. 10-13 , however in this embodiment another different means for attaching a ground conductor is illustrated. The ground clamp  510  in this embodiment has a pad  542  having a threaded hole with screw  548  threaded therein. Therefore, a ground conductor or wire, not shown, wrapped around or placed under screw head  549  may be securely held by tightening screw  548  within the threaded hole and securing the ground conductor or wire adjacent the pad  542 . 
         [0055]    As illustrated in  FIGS. 10-15 , the ground clamps illustrated therein provide the additional advantage of having a terminal block formed thereon for attaching or retaining a ground conductor for a multiple number or plurality of electrical devices. The plurality of retainers permits additional electrical devices to be grounded without disrupting or removing the ground clamp. This saves considerable time when connecting additional electrical devices and provides a more reliable ground connection. 
         [0056]    While the present invention has been described with respect to several different embodiments, it will be obvious that various modifications may be made without departing from the spirit and scope of this invention.