Abstract:
A wire guide for electrical boxes utilizes a wire-guiding and support pulley mounted to the front of an attachment plate to feed or retrieve wire or cable from an electrical box. An access aperture provides access to the electrical box for hands or tools. Attachment screws  302  secure attachment plate to the electrical box through a plurality of attachment holes. Multiple attachment hole patterns allow use of the guide with various types of electrical boxes and allow attachment of the guide for vertical and horizontal offsets.

Description:
FIELD OF THE INVENTION 
     The present invention relates to wire guides for pulling wire in conduits and, more particularly, to wire guides attachable to electrical boxes. 
     BACKGROUND OF THE INVENTION 
     Many products and tools have been introduced to aid pulling wire and cable in conduits in residential, commercial and industrial buildings. Some of these products address the problems associated with reducing strain and abrasion and cutting damage to wire and cable when pulling through electrical boxes. For example, U.S. Pat. No. 5,271,605 discloses a wire guide device for installation in a tile wall cover. The device fits inside a standard outlet box and utilizes a guide pulley that extends into a junction box. U.S. Pat. No. 4,541,615 discloses a guide roller for feeding electrical wire into a conduit. The roller utilizes a hanging bracket that attaches to holes in an electrical box. 
     These and other devices, while having utility, lack the flexibility for use with a number of different electrical box types, or for use in different stages of wall construction. For example, some of the devices are designed for one type of box only. Others cannot be used once wall panels surrounding the box have been installed. Many lack structural design for pulling multiple wires or heavy cable. Still others limit access to the interior of an electrical box, complicating retrieval of wire and cable ends and use of tools. 
     An improved wire and cable guide tool is needed which addresses the shortcomings of present devices used in pulling wire and cable. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide a wire guide for electrical boxes that can be used on a large variety of common electrical connection, utility and junction boxes. 
     Another object of the present invention is to provide a wire guide for electrical boxes that is robust in design and construction and can be used to pull multiple wires and heavy cable. 
     Another object of the present invention is to provide a wire guide for electrical boxes that can be used in any stage of wall construction around the electrical box. 
     Another object of the present invention is to provide a wire guide for electrical boxes that provides maximum access of hands and tools to the interior of the box when installed for ease of use. 
     Yet another object of the present invention is to provide a wire guide for electrical boxes that allows placement of the guide in 90-degree rotated configurations to allow pulling wire and cable from vertical or horizontal offsets. 
     Still another object of the present invention is to provide a wire guide for electrical boxes that is simple and low in cost. 
     The wire guide of the present invention comprises a shallow V-groove pulley rotateably attached to the front of an attachment plate. The attachment plate utilizes a number of attachment through-hole patterns corresponding to, and aligning with, threaded cover plate holes of a variety of standard electrical utility, connection and junction boxes. At least some of the through-hole patterns utilize twice the holes as cover plate screws used in the boxes to allow 90-degree rotation of the attachment plate with respect to the box. The forward position of the pulley so that it does not extend beyond the back face of the attachment plate allows attachment and use of the device even if wall panels have been installed up to the box. 
     The attachment plate utilizes a large access hole or aperture through the plate for hand and tool access inside the box with the guide attached. The access hole utilizes outwardly extending lobes so that the radius from a geometric center of the attachment hole patterns to the outer portions of the lobes is a greater distance than the closest distance from the geometric center of the attachment hole patterns to the attachment holes. 
     The simple and robust design of the guide allows multiple wires and heavy cable to be supported by the device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features, aspects and advantages of the present invention will become better understood with regard to the following description, appended claims and accompanying drawings where: 
     FIG. 1 is an exploded view of the wire guide showing the attachment plate with central access aperture, a V-groove pulley supported by shafts and bearings on either end of the pulley, and clamp blocks for clamping the shafts to the attachment plate; 
     FIG. 2 is a front view of the attachment plate of FIG. 1 showing the multiple through-hole patterns for attachment to a variety of electrical boxes; and 
     FIG. 3 is a side elevation drawing of the wire guide of FIG. 1 attached to an electrical box with the pulley supporting a wire being pulled through a conduit connected to the box. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following is a description of the preferred embodiments of a wire guide for electrical boxes. 
     FIG. 1 is an exploded view of wire guide  101  showing a wire pulley  103  supported by shafts  105 A,  105 B to attachment plate  107 . In the preferred embodiments, wire pulley  103  is a generally shallow V-groove pulley providing rolling support of a wire as it is fed into, or pulled from, an electrical box as shown in FIG.  3 . 
     Bearings such as needle bearings  109 A,  109 B, secured into recesses  111 A,  111 B of pulley  103  by a press fit provide a low-resistance means of rolling support of pulley  103  on shafts  105 A,  105 B. Clamp blocks  115 A,  115 B clamp shafts  105 A,  105 B into cylindrical grooves  117 A,  117 B on the front face  107 A of attachment plate  107 . Fasteners such as cap screws  121  fasten clamp blocks  115 A,  115 B to attachment plate  107  by engagement with threaded holes  123 . Drilled lubrication holes  125 A,  125 B in shafts  105 A,  105 B provide a means for lubrication of bearings  109 A,  109 B. 
     Access aperture  127  provides access for wire or cable routed into, and out of, an electrical box as shown in FIG.  3 . Chamfered edge  129  provides protection from abrasion or cutting of the wire or cable if in contact with interior surface  131  of aperture  127 . 
     FIG. 2 is a front view of attachment plate  107  showing access aperture  127  and several sets of attachment holes for attaching plate  107  of guide  101  to an electrical box such as octagon box  301  of FIG.  3 . For example, attachment holes  201 A are positioned to align with threaded holes  303  of cover support ledges  305  of octagon box  301  of FIG.  3 . Standard octagon electrical boxes utilize only a pair of cover plate threaded holes  303  and cover support ledges  305 . Use of four holes  201 A provide a means to attach wire guide  101  in any of four quadrants (90 degree rotations). The ability to rotate the guide in 90-degree quadrants allows the wire to be fed from a variety of directions. 
     Attachment holes  201 B are positioned to align with the cover attachment holes of a standard 4″ electrical box. As in the case of holes  201 A, four holes positioned as shown allows guide  101  to be rotated in 90 degree quadrants, even though standard 4″ boxes have only two lid attachment holes. 
     Attachment holes  201 C are positioned to align with cover attachment holes of a standard 4{fraction (11/16)}″ electrical box. Use of eight holes (double the number of cover attachment holes in the electrical box) allows attachment in 90-degree rotation quadrants. Holes  201 D are positioned to align with threaded cover plate attachment holes in standard receptacle boxes, and holes  201 E are positioned to align with double receptacle boxes. 
     Point  203  defines the geometric center of the arrays of holes  201 A,  201 B,  201 C,  201 D, and  201 E. Lines shown in the figure illustrate the center of arrays for holes  201 A,  201 C and  201 D. In the preferred embodiment, point  203  also represents the geometric center of access aperture  127 . 
     In the preferred embodiments, access aperture  127  is enlarged to a maximum practical amount in order to provide adequate space for multiple wire and cables, and to provide access for fingers and tools inside the electrical box during use. Aperture lobes such as lobes  205  extend outward from geometric center  203  greater than the distance to the most inward attachment holes. For example, distance  207  to lobe  205  from geometric center  203  exceeds distance  209  to attachment hole  201 D. Distance  213  to lobe  211  exceeds distance  215  to attachment hole  201 A. 
     FIG. 3 is a side elevation drawing of attachment plate  107  of wire guide  101  fastened to an electrical box such as octal box  301 . Cap screws  121  fasten clamp block  115 A to attachment plate  107 , clamping shaft  105 A to plate  107 . The diameter of pulley  103 , plate  107  thickness and positioning of shaft  105 A are selected to ensure that pulley  103  does not extend beyond the back  107 B of plate  107 . This ensures that the device may be used with small boxes such as outlet boxes and when wall structure may otherwise interfere with the installed wire guide. 
     Plate attachment screws  302  pass through attachment holes  201 A and are engaged to threaded holes  303  of cover support ledges  305 . In the preferred embodiments, threaded attachment screw holes  135  on clamp blocks  115 A,  115 B provide a storage location for attachment screws  302  when not in use. Wire pulley  103  provides rolling support to wire  307  as it is pulled into or, out of, conduit  309  fixed to box  301 . In FIG. 3, shaft  105 A of wire pulley  103  is shown in a horizontal position, allowing pulley  103  to provide wire feed  313  and support when offset in a vertical, or near-vertical direction  311 . Upon rotation of guide  101  as described above, pulley  103  provides wire feed and support when offset in a horizontal, or hear-horizontal direction. 
     In the preferred embodiments, attachment plate  107  is made of aluminum plate and anodized in order to provide corrosion protection and reduce friction of wire on access aperture surfaces such as chamfer  129  and interior surface  131  if FIG.  1 . Wire pulley  103  is machined from aluminum rod, clamp blocks  115 A,  115 B are machined from aluminum shapes. Shafts  105 A,  105 B are hardened steel. In other embodiments, other metals or high-strength engineered plastic materials may be used. Plate  107  and clamp blocks  115 A,  115 B may be integrally molded or fabricated from metals or high-strength plastics. 
     In the preferred embodiments, pulley  103  is a V-groove pulley having shallow (less than 30 degrees) bearing surfaces  139  with centerline axis  141 . The shallow bearing surface angle provides a small centering bias on the wire or cable during pulling, yet allows use of conduit offset with respect to the centerline of the box. On other embodiments, a truncated or flat portion  143  of the pulley extends for a portion of width of the pulley. Pulley  103  extends the substantial width of aperture  127 , and in the preferred embodiments, extends at least 60% of the width of wire guide  101 . Other embodiments utilize a single shaft extending through pulley  103 . Journal bearings may be used instead of ball or needle bearings. Still other embodiments utilize two or more access holes instead of a single large hole. 
     Accordingly, the reader will see that the Wire Guide for Electrical Boxes provides a device for pulling wire and cable in a variety of electrical boxes. The device provides the following additional advantages: 
     The guide can be rotated 90 degrees and mounted to the electrical box for offset pulling from a horizontal or vertical direction; 
     The guide provides a large access aperture for better viewing and insertion of hands or tools; 
     The guide can be used with electrical boxes in any stage of wall construction; and 
     The device is robust, simple and low in cost. 
     Although the description above contains many specifications, these should not be construed as limiting the scope of the invention but merely providing illustrations of some of the presently preferred embodiments of this invention. Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.