Patent Publication Number: US-2012024596-A1

Title: Plastic cable clamps designs in steel outlet boxes

Description:
This application is a divisional application of U.S. patent application Ser. No. 12/578,874, filed on Oct. 14, 2009, and claims priority from provisional application Ser. No. 61/196,162, filed on Oct. 15, 2008, both of which are incorporated herein in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention is a cable clamp for securing cables and wires to an electrical enclosure. In particular, the invention relates to a flexible cable clamp that compressively engages cables and wires entering an electrical outlet box. 
     BACKGROUND OF INVENTION 
     An electrical outlet box provides a termination point for wires carrying electrical current through buildings, houses, and other structures. Wiring entering an electrical outlet box is typically connected to an electrical device, such as a receptacle or switch, mounted within the box. The box is usually covered by a face plate having an opening that allows access to the receptacle or switch while preventing contact with the wires inside the box. Outlet boxes are often used in installations where the wires are located within a wall or ceiling. Alternatively, outlet boxes may be used in exposed-conduit wiring installations where they are mounted on the surface of a structure, such as a wall, column or ceiling. 
     Outlet boxes are available in a variety of configurations and sizes. The type of box selected depends on the specific requirements of the application. Outlet boxes typically include a plurality of openings which provide entry for the wires into the box. These openings are usually covered by removable portions called “knockouts,” which can be easily removed by the installer as required. With most electrical devices, the outlet box is spacious enough to accommodate a sufficient length of excess wiring so that a connected device can be removed from the outlet box and serviced without disconnecting the device from the wiring. 
     To install an electrical device in an outlet box, an installer pulls the end of electrical wires or cable, through a knockout opening in the box. A long enough length of wires is pulled through the knockout to allow the wires to be connected to the electrical device outside the outlet box, where the installer has more room to work. After the wires are connected to the electrical device, the device is secured in the outlet box. The outlet box is designed to have sufficient volume and depth so that the excess wires can be easily packed into the box. 
     In many cases, the person who runs the wires/cable into the outlet box is not the same person who installs the device. Therefore, the wires/cable may not immediately be connected to the electrical device. Even if there is no appreciable time interval in between the steps, it is easier for the installer if the wire(s)/cable is secured to the box. To facilitate the installation, a clamp is typically used to hold the wires/cable in place (i.e., in the outlet box) and thereby free the installer&#39;s hands for other tasks. The use of a clamp also allows the wires to be pulled through and held in the outlet box long before a device is connected. 
     Many of the prior art clamps used to retain wires/cables in steel outlet boxes require the installer to thread the wires through the clamp or require the clamp to be fastened to the box once the wires are installed. Typically, a screw is used to secure the clamp to the outlet box and, in a constricted work space, this can be cumbersome and require excessive installer dexterity. Therefore, it is desirable to provide a clamp for an electrical outlet box which can be quickly and easily removed and inserted and which allows easy installation of wires into an outlet box without the difficulties of the prior art devices. 
     Moreover, most steel outlet boxes that are currently available have all of the components made of steel. Wires or cables entering the box are typically clamped in place using a steel clamp and screw. Two of the objectives for the cable clamp design are low manufacturing cost and ease of use. However, in the highly competitive field of outlet box manufacture, these objectives have not been fully achieved. Moreover, the clamping systems currently used for metal electrical outlet boxes have several disadvantages. They typically require a tool to tighten the clamp against the wire or cable, which makes the installation more difficult and increases the installation time. They also use a screw to secure the clamp which increases the cost and makes the manufacture of the electrical box more complex and expensive since the box must include a threaded aperture for receiving the screw. Accordingly, there is a need for a less expensive clamp that is not made of metal and does not use a screw to attach it to the electrical box. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a cable clamp for securing a wire or cable in an electrical outlet box having an interior, an exterior and one or more openings therebetween is provided. The cable clamp includes a body and one or more retaining devices that define one or more apertures. The body is adapted to mount in one of the one or more openings in the electrical outlet box and each of the one or more apertures is adapted to provide a passage for a wire or cable between the interior and exterior of the electrical outlet box. The one or more retaining devices are connected to the body and each of the one or more retaining devices is adapted to secure a wire or cable in one of the one or more apertures. 
     In a first embodiment of the cable clamp, each of the one or more retaining devices includes a pair of pivotably movable doors. The pivotably movable doors can be attached to hinges. In addition, each of the one or more apertures can have a pair of opposing sides and the pair of pivotably movable doors can be resiliently attached to the pair of opposing sides. The pivotably movable doors pivot into the electrical outlet box when a force is applied and pivot back into the one or more apertures when the force is released. 
     In a second embodiment of the cable clamp, each of the one or more retaining devices includes one or more flexible arcuate members in each of the one or more apertures. Each of the flexible arcuate members is adapted to move through the aperture into the interior of the box when a force is applied from the exterior of the box. The body can also include one or more substantially rigid bases located on the second, opposing side of the aperture. A wire or cable is secured in one of the apertures between the flexible arcuate member and the substantially rigid base. The cable clamp can also include an anchoring device that is adapted to secure the body in the opening in the electrical outlet box. 
     In a third embodiment of the cable clamp, each of the one or more retaining devices includes two opposing flexible members. Each flexible member has a first end, a second end and a stop. Each of the one or more apertures in the body can have a pair of opposing sides and the first ends of the two opposing flexible members are attached to the pair of opposing sides. The two opposing flexible members pivot into the interior of the electrical outlet box and the stops are adapted to resiliently oppose the movement of the flexible members into the interior. The second end of each of the two opposing flexible members can have a recessed center portion that is adapted to cooperatively receive the wire or cable. 
     In a fourth embodiment of the cable clamp, each of the one or more apertures has a first side and a second side and each of the retaining devices includes a pivotal door. The pivotal door has an interior side and an exterior side and is attached to the first side of each of the one or more apertures. A plurality of teeth is located on the second side of each of the one or more apertures. A compressible component is attached to the interior side of the pivotal door and is adapted to oppose the movement of the pivotal door into the interior of the electrical box. 
     In a fifth embodiment of the cable clamp, each of the one or more apertures has a first side and a second side and each of the retaining devices includes a pivotal door. The pivotal door has an interior side and an exterior side attached to the first side of each of the one or more apertures. A plurality of teeth is located on the second side of each of the one or more apertures. The pivotal door has a substantially flat portion and a flexible member, which extends from the interior side of the pivotal door. The flexible member is adapted to oppose the movement of the pivotal door into the interior of the electrical box. 
     In a sixth embodiment of the cable clamp, each of the one or more apertures has a first side and a second side and each of the one or more retaining devices includes a pair of inwardly biased opposing members having a first end and a second end. The first ends of the pair of inwardly biased opposing members are attached to the first and second sides of the aperture and the second ends are adapted to cooperatively secure the wire or cable. The second ends of the pair of inwardly biased opposing members can extend into the interior of the electrical outlet box and can compressively contact each other. 
     In a seventh embodiment of the cable clamp, each of the one or more retaining devices includes a port having a large aperture and a small aperture. The large aperture is connected to the small aperture. The large aperture is adapted to provide a passage for a wire or a cable between the exterior and the interior of the electrical outlet box. After the wire or cable passes through the large aperture it is moved into the small aperture, which is adapted to snugly receive the wire or cable and secure it in the port. 
     In an eighth embodiment of the cable clamp, each of the one or more apertures has a first side and a second side and each of the one or more retaining devices includes a pair of inwardly biased opposing members having a first end and a second end. The first ends of the pair of inwardly biased opposing members are attached to the first and second sides of the aperture and the second ends are arcuately shaped and adapted to cooperatively secure the wire or cable in the aperture. The second ends of the pair of inwardly biased opposing members can extend into the interior of the electrical outlet box and can compressively contact each other. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The preferred embodiments of the clamp for an outlet box of the present invention, as well as other objects, features and advantages of this invention, will be apparent from the accompanying drawings wherein: 
         FIG. 1  is a perspective view of the back wall and two end walls of an electrical box with a first embodiment of the clamp of the present invention in the end walls. 
         FIGS. 2A , B and C are perspective, side and end views, respectively, of a second embodiment of the clamp of the present invention in the end wall of an electrical outlet box. 
         FIGS. 3A , B and C are an end view and two side views, respectively, of a third embodiment of the clamp of the present invention showing a clamp with no wires, a single wire and two wires, respectively, in the end wall of an electrical outlet box. 
         FIGS. 4A , B and C are an end view and two side views, respectively, of a fourth embodiment of the clamp of the present invention showing a clamp with no wires, a single wire and two wires, respectively, in the end wall of an electrical outlet box. 
         FIGS. 5A , B and C are an end view and two side views, respectively, of a fifth embodiment of the clamp of the present invention showing a clamp with no wires, a single wire and two wires, respectively, in the end wall of an electrical outlet box. 
         FIG. 6  is a perspective view of the back wall and two end walls of an electrical box with a sixth embodiment of the clamp of the present invention in the end walls. 
         FIG. 7  is a perspective view of the back wall and two end walls of an electrical box with a seventh embodiment of the clamp of the present invention in the end walls. 
         FIGS. 8A , B and C are an exterior perspective, top and interior perspective views, respectively, of an eighth embodiment of the clamp of the present invention in the end wall of an electrical outlet box. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to cable clamps that fit in an opening in a steel electrical outlet box and retains wires that enter the box through the opening. The cable clamps can be made of plastic or metal or a combination of both materials. The cable clamps can have flexible or spring members that are used to secure wires or cables that enter outlet boxes through openings in one of the walls. The cable clamps fit into an opening in the outlet box and one or more flexible retaining members are attached to the sides of one or more apertures in the clamp. Wires or cables entering the outlet box are inserted through the aperture and are engaged by the flexible retaining members to secure them in place. For the present disclosure, the terms wire and cable are used interchangeably and the use of one term or the other is not intended to limit the scope of the invention in any way. 
     The cable clamps of the present invention can be quickly and easily attached to an opening in an electrical outlet or junction box. The clamps can be oriented as desired by the user. For example, the retaining devices can be vertically or horizontally disposed in relation to each other and the back wall of the box. In addition, the cable clamps have a low manufacturing cost and efficiently grip the wires or cables and tighten against them when a force is exerted to pull the wires or cables out of the box. 
     The scope of the present invention includes a variety of different embodiments of the cable clamp with different retaining devices. Preferably, each cable clamp includes two retaining devices but the invention is not limited to cable clamps having two retaining devices. The present invention is also intended to cover cable clamps having one retaining device as well as cable clamps having three or more retaining devices. Each retaining device is preferably formed by two retaining members that flexibly receive and secure a wire(s) or cable in an electrical box. In general, the common feature of the cable clamps of the present invention is that the flexible members resist removal of the wires/cable in a manner similar to a “Chinese finger grip,” i.e., the more force applied to pull the wires/cable out of the outlet box, the tighter the members grip the sides of the wires/cable. 
     The cable clamps include a body and one or more retaining devices attached to the sides of one or more apertures in the body. The body is adapted to mount in an opening in an electrical outlet box and the apertures are adapted to provide a passage for wires and/or cables between the interior and exterior of the electrical outlet box. The retaining devices secure the wires or cables in the apertures. The retaining devices can include a pair of pivotably movable or hinged doors, a flexible arcuate member, two opposing flexible members, a pivotal door with a compressible component and a plurality of teeth, a pivotal door with a flexible member and a plurality of teeth, a pair of inwardly biased opposing members, a port having a small aperture and a large aperture, or a pair of opposing flexible members with arcuate ends. 
     Referring now to the drawings,  FIG. 1  shows a first embodiment of the cable clamp  110  installed in an electrical box (only the opposing end walls  120  and back wall  122  of the box are shown). The cable clamp  110  installed on one end wall  120  and secured by an anchoring device  124  includes a body  111  with two apertures  113 ,  115  and two retaining devices  112 ,  114  located in the apertures  113 ,  115 . Each retaining device  112 ,  114  has a pair of pivotably movable doors  116 ,  118  attached to hinges  117 ,  119  on the opposing sides  133 ,  135  of the apertures  113 ,  115 . 
       FIG. 1  also shows a variation of the first embodiment of the cable clamp  110 ′ installed on the other end wall  120 ′, which includes a body with two apertures  113 ′,  115 ′ and two retaining devices  112 ′,  114 ′ located in the apertures  113 ′,  115 ′. The retaining devices  112 ′,  114 ′ include a pair of pivotably movable doors  116 ′,  118 ′ that are resiliently attached to the opposing sides  133 ′,  135 ′ of the apertures  113 ′,  115 ′. 
     The pivotably movable doors  116 ,  118  or  116 ′,  118 ′ pivot into the interior of the electrical outlet box when a force is applied from the exterior of the box and pivot back into the one or more apertures  113 ,  115  and  113 ′,  115 ′ when the force is released. When wires  130  enter the electrical box through either of the end walls  120 ,  120 ′, the pivotably movable doors  116 ,  118  or  116 ′,  118 ′ exert a compressive force against the wires  130  and secure them in place. Although  FIG. 1  shows cable clamps  110 ,  110 ′ that have two retaining devices  112 ,  114  and  112 ′,  114 ′, respectively, for securing wires  130 , the first embodiment (as well as the other embodiments) of the cable clamp is not limited to two retaining devices and can have one retaining device or three or more retaining devices. 
       FIGS. 2A , B and C show two variations of a second embodiment of the cable clamp  210 ,  210 ′, which are preferably made of spring steel.  FIG. 2A  shows a variation of the second embodiment of the cable clamp  210  that includes a body  211  with two flexible arcuate members  212 ,  214  on the exterior of the end wall  220  of the electrical box. The cable clamp  210  is installed in the end wall  220  of an electrical outlet box and the two flexible arcuate members  212 ,  214  extend outwardly from the end wall  220  and then curve downwardly and inwardly. The flexible arcuate members  212 ,  214  define two apertures  213 ,  215  in the clamp  210  and each can independently secures a cable  230  in the box. Each of the flexible arcuate members  212 ,  214  is adapted to flex inwardly in the direction of (or into) the interior of the box when a force is applied from the exterior. The clamp  210  can also have a base  218  opposing the curved end of the flexible arcuate members  212 ,  214 . After the wire  230  is inserted through the clamp  210 , the flexible arcuate members  212 ,  214  press the wires  230  against the base  218  to secure them in place. 
       FIGS. 2B and 2C  show another variation of the second embodiment of the cable clamp  210 ′ having two flexible arcuate members  214 ′ that are substantially flush with the end wall  220 ′ of the electrical box. The cable clamp  210 ′ is installed over at least one opening in the end wall  220 ′ and the two flexible arcuate members  214 ′ define two apertures  213 ′,  215 ′. When an electrical wire or cable  230 ′ is installed in the electrical box, one of the two flexible arcuate members  214 ′ is pushed inwardly through one of the apertures  213 ′,  215 ′ and into the interior of the electrical box. The cable clamp  210 ′ can also include an anchoring device  224 ′ that is adapted to secure the body  211 ′ to the end wall  220 ′ of the electrical outlet box. 
       FIGS. 3A , B and C show a third embodiment of the cable clamp  310  which has a body  311  mounted in the end wall  320  of an electrical outlet box. The body  311  has an aperture  313  with two opposing sides  315 ,  317  and two opposing flexible members  312 ,  314  extending from the two opposing sides  315 ,  317  of the aperture  313 . The two opposing flexible members  312 ,  314  is pivotably attached to the two opposing sides  315 ,  317  of the body  311  on one end and the unattached ends  316 ,  318  are aligned near the middle of the aperture  313 . When a force is applied, the two opposing flexible members  312 ,  314  move from a closed position, wherein the two opposing flexible members  312 ,  314  restrict access to the interior of the electrical box, to an open position, wherein the two opposing flexible members  312 ,  314  pivotably rotate into the interior of the electrical box to allow the passage of one or more wires or cables  330 ,  332  into the box. The unattached ends  316 ,  318  of the two flexible members  312 ,  314  can have recessed edges  319 ,  321 , respectively, that are adapted to cooperatively receive and secure the wires or cables  330 ,  332  ( FIGS. 3B  and C) in the box. After the wire(s)  330 , ( 332 ) is inserted through the aperture  313  in the cable clamp  310 , the flexible members  312 ,  314  press against the wire(s)  330 , ( 332 ) to secure it in place. The flexible members  312 ,  314  can have resilient stops  324 ,  326  on the interior surfaces, which are adapted to resiliently oppose the movement of the flexible members  312 ,  314  into the interior of the box when a force is applied to install the wire(s)  330 , ( 332 ) in the box. 
       FIGS. 4A , B and C show a fourth embodiment of the cable clamp  410 , which has a body  411  mounted in the end wall  420  of an electrical outlet box. The body  411  has an aperture  413  with two opposing sides  415 ,  417  and a pivotal door  412  attached to one opposing side  415  and a plurality of teeth  414  on the other opposing side  417 . One or more wires or cables  430 ,  432  ( FIGS. 4B  and C) are inserted in the aperture  413  and secured in place between the pivotal door  412  and the plurality of teeth  414 . After the wire(s) or cable(s)  430 ,  432  is inserted through the aperture  413  in the clamp  410 , the pivotal door  412  presses against the wire(s)  430 ,  432  and the plurality of teeth  414  engage the wire(s)  430 ,  432  to secure it in place. The unattached end  416  of the pivotal door  412  can have a recessed edge  419  that is adapted to receive and secure the wires or cables  430 ,  432  ( FIGS. 4B  and C) in the box. The pivotal door  412  has a compressible component  418  attached to the interior side, which is adapted to oppose the movement of the pivotal door  412  into the interior of the electrical box when the pivotal door  412  flexes inwardly to receive the wire(s)  430 ,  432 . 
       FIGS. 5A , B and C show a fifth embodiment of the cable clamp  510 , which has a body  511  mounted in the end wall  520  of an electrical outlet box. The body  511  has an aperture  513  with two opposing sides  515 ,  517  and a pivotal door  512  with a flexible member  518  attached to one opposing side  515  and a plurality of teeth  514  on the other opposing side  517 . One or more wires or cables  530 ,  532  ( FIGS. 5B  and C) are inserted in the aperture  513  and secured in place between the pivotal door  512  and the plurality of teeth  514 . After the wire(s) or cable(s)  530 ,  532  is inserted through the aperture  513  in the clamp  510 , the pivotal door  512  presses against the wire(s)  530 ,  532  and the plurality of teeth  514  engage the wire(s)  530 ,  532  to secure it in place. The flexible member  518  is attached to the interior side of the pivotal door  512  and is adapted to oppose the movement of the pivotal door  512  into the interior of the electrical box. When the pivotal door  512  flexes inwardly to receive the wire(s)  530 ,  532  the flexible member  518  exerts a force against the wire(s)  530 ,  532  to snugly retain them in the clamp  510 . 
       FIG. 6  shows a sixth embodiment of the cable clamp  610  mounted in the end walls  620  of an electrical box having a pair of end walls  620  extending from a side wall  622 . The cable clamp  610  includes a body  611  with two apertures  613 , wherein each aperture  613  has a pair of opposing sides  615 ,  617  and a pair of inwardly biased opposing members  612 ,  614 . Each of the inwardly biased opposing members  612 ,  614  has first and second ends  616 ,  618 , wherein the first end  616  is connected to one of the sides  615 ,  617  of one of the apertures  613  and the second ends  618  compressively contact each other. The inwardly biased opposing members  612 ,  614  extend into the interior of the electrical outlet box and move apart when a wire  630  is inserted through the aperture  613 . After the wire  630  passes through the aperture  613 , the inwardly biased opposing members  612 ,  614  cooperatively exert a compressive force against the wires and secure them in place. An anchoring device  624  can be used to retain the cable clamp  610  in the end wall  620  of the electrical box. 
       FIG. 7  shows a seventh embodiment of the clamp  710  mounted in the end wall  720  of an electrical box. The cable clamp includes a body  711  with two ports  712 ,  714  having a small aperture  716 ,  718  and a large aperture  717 ,  719 . The wire or cable  730  entering the electrical box (the opposing end walls  720  and back wall  722  of the box are shown) are inserted through the large aperture  717 ,  719  of one of the ports  712 ,  714  and then moved into the small aperture  716 ,  718 , which snugly engages the wire/cable  730  and secures it in place. 
       FIGS. 8A , B and C show an eighth embodiment of the clamp  810  in the end wall  820  of an electrical box. The clamp  810  includes a body  811  having two apertures  813  with a pair of opposing sides  815 ,  817 . A retaining device  812  is formed in each aperture  813 . The retaining device  812  includes a pair of biased flexible arcuate members  816 ,  818  having a first end  819 ,  821  and a second end  823 ,  825 , respectively. The first end  819 ,  821  of each biased flexible arcuate members  816 ,  818  is attached to one of the opposing sides  815 ,  817  of the aperture  813  and the second ends  823 ,  825  extend into the interior of the box and curve away from each other. The flexible arcuate members  816 ,  818  are normally in a closed position and limit access to the electrical box through the apertures  813  in the retaining devices  813 . The application of a force on the exterior of the flexible arcuate members  816 ,  818  pushes them into the interior of the electrical box and provides access through the apertures  813 . The pair of biased flexible arcuate members  816 ,  818  act cooperatively to compressively secure a wire or cable  830  therebetween. The wire/cable  830  enters the electrical box (the opposing end walls  820  and back wall  822  of the box are shown) through one of the apertures  813  and the biased flexible arcuate members  816 ,  818  flex apart to receive the wire/cable  830 . The biased flexible arcuate members  816 ,  818  exert a compressive force against the wire/cable  830  to secure it in place. The flexible arcuate members  816 ,  818  are provided with a flexible member  826 ,  828  that opposes the inward movement when a force is applied from the exterior. When the force is released, the flexible member  826 ,  828  force the flexible arcuate members  816 ,  818  towards each other. 
     Thus, while there have been described the preferred embodiments of the present invention, those skilled in the art will realize that other embodiments can be made without departing from the spirit of the invention, and it is intended to include all such further modifications and changes as come within the true scope of the claims set forth herein.