Abstract:
A utility cross arm assembly for supporting electrical wires from a utility pole. The entire assembly is constructed from insulative materials. It is provided with easily replaceable wire support members or protective caps to enhance convertibility from a single phase delivery configuration to a three phase delivery configuration. The assembly frame provides left and right cross arms with an upper support neck. Various arms and legs provide structural support and a way to mount the assembly to the utility pole. Large open spaces between the arms and legs provide a lightweight construction with low air resistance upon mounting to the utility pole.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an electric utility cross arm; and, more particularly, to an insulated unit which is easily convertible from single phase to three phase delivery. Further, the present invention provides a cross arm of simple, two-section, reinforced construction. 
     Power transmission lines are supported above ground to ensure isolation between the lines and the environment. While the most common arrangement for supporting such lines comprises a plurality of glass electrical insulators mounted on wooden cross arms attached to vertical wooden poles, U.S. Pat. No. 4,682,747 teaches the use of a modular power transmission support structure. This structure comprises a generally triangular central portion and two horizontal arms extending laterally from the base of the central triangular portion. The structural members of these cross arms comprise an outer shell formed of a polyester resin material and a plurality of alternating layers of polyester resin material and synthetic fabric contained within the shell. The inner core of each structural member contains a longitudinally extending metal bar or cable surrounded by a mixture of polyester resin and particulate matter. The present invention is a further improvement on this polyester resin, metal core structure. The elimination of the metal core and the substitution of reinforcing ribs reduces the weight of the assembly significantly and allows for the entire assembly to be of molded construction. 
     SUMMARY OF THE INVENTION 
     The present invention is a utility insulated cross arm assembly for supporting electrical wires from a utility pole. The assembly is constructed entirely from an insulative material. The assembly may be easily converted from a single phase to a three phase delivery configuration by replacing an internally threaded insulator cap with an internally threaded wire support member. Split frame sections having internal reinforcing ribs are joined to form a unitary frame having left and right horizontal cross arms with vertically extending threaded insulator pins adapted to receive an internally threaded cap or wire support member. An upper support neck is provided at the peak of the frame with an insulator pin. A horizontal support member, a central support leg, and two additional diagonal support legs provide support for the horizontal cross arms without the need for a metal core used in the prior art. Two upwardly diagonal support arms are attached to the upper support neck and the horizontal cross arms to complete a support arrangement for the entire frame. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevation view of the present invention without insulator members on the insulator pins. 
     FIG. 1A is a front elevation view of an alternative embodiment of the present invention without insulator member on the insulator pins. 
     FIG. 2 is an exploded side view of the present invention illustrating the split frame sections, the threaded pins with cylindrical bases and the adaptor sleeves. 
     FIG. 2A is an exploded side view of an alternative embodiment of the present invention illustrating the it frame sections, threaded pins, and adaptor sleeves. 
     FIG. 3 show view along line 3--3 of FIG. 2, illustrating the internal ribs of the back frame section. 
     FIG. 3A shows a view along line 3A--3A of FIG. 2A, illustrating the internal ribs of the back frame section. 
     FIG. 4 is a perspective view of a wire support member of the present invention with watershed rings. 
     FIG. 4A is a perspective view of an alternative wire support member embodiment of the present invention 
     FIG. 5 is a perspective view of a second size wire support member with watershed rings with the internal thread shown in broken lines. 
     FIG. 5A is a perspective view of a second size wire support member alternative embodiment of the present invention with internal threads shown in broken lines. 
     FIG. 6 is a perspective view of an insulator cap of the present invention with internal threads shown in broken lines. 
     FIG. 6A is a perspective view of an alternative insulator cap of the present invention with internal threads shown in broken lines. 
     FIG. 7 illustrates a side view of an insulator pin with a cylindrical base member. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference now to the FIG and in particular to FIG. 1 and 1A, there is depicted a front elevation view of the convertible utility insulated cross arm assembly 10 without any insulator member on the vertically extending, taper-threaded insulator pins 12A, 12B, and 12C. 
     Left 14 and right 16 horizontal cross arms are integrally molded as part of the frame 18. A horizontal support member 20 connects end supports left 14 and right 16 cross arms. 
     An upper support neck 22 is integral with and located at a peak 24 of the frame 18. A central support leg 26 depends downwardly at a first end 28 from the mid-section 30 of the horizontal support member 20. From a second end 32 of the central support leg 26, a left diagonal support leg 34 extends upwardly to and connects with the distal end 36 of the left cross arm 14. Leg 34 provides strength to the frame 18 and particularly supports the left 14 cross arm when the cross arm is carrying the weight of the transmission wires (not shown). A right diagonal support leg 38 is also connected to the second end 32 of the central support leg 26. Leg 38 extends upwardly to and connects with the distal end 40 of the right cross arm 16 providing structural support for the right side of the frame. 
     A first upward diagonal support arm 80 extends from the distal end 36 of the left horizontal cross arm 14 to the upper support neck 22. A second upward diagonal support 82 likewise extends from the distal end 40 of the right horizontal cross arm 16 to the upper support neck 22. 
     The utility cross arm assembly 10 may be mounted to a utility pole by means of central holes 42, 44, and 46. In the preferred embodiments, fasteners (bolts) are inserted through these holes and then fastened to the utility pole. Mounting holes 48 and 49 may be used to attach a disconnect, bells for double deadend apparatuses, and lighting arrestors (not shown). A sleeve 50 may be inserted into the mounting holes to facilitate various sizes of fasteners. 
     FIG. 2 illustrates the split frame sections 52 and 54. Front face section 52 and back frame section 54 are mirror images of one another, except that front section 52 has the tongue member 56 and back section 52 has the grooves 58. When assembled, appropriate adhesives are used to join the two frame sections. 
     Vertically extending taper-threaded insulator pins 12B and 12C with cylindrical base member 60 may be seen in FIGS. 2 and 7. A fastener receiving conduit 61 extends through the entire length of the base member 60. Conduit 61 aligns with openings 48 and 49 in the cross arms 14 and 16. Base member 60 is received into a cooperating space within the reinforced ribbing 70 internal to the frame sections 52 and 54 (see FIG. 3). The base member 60 may receive a sleeve insert 50 as appropriate. 
     FIG. 3 illustrates the internal ribbing 70 within the back frame section 54. Again, the ribbing is mirror imaged in the face section. A groove 58 extends around the outside of the section 54 to accept the tongue 56 from the face section 52. Ribbing is provided to reinforce the frame and the mounting holes 42, 44, 46. The frame is constructed of compression molded fiberglass or sheet molding compound. A vinyl ester or polyvinyl ester resin may be used in combination with fiberglass. This provides a cross arm assembly which is entirely of insulated materials. 
     Hollow chambers 72 are formed between the ribbing 70 and yield a lightweight frame. Further, FIG. 3 shows that left 80 and right 82 upper diagonal support arms are spaced apart at a mid-section 81 and 83 from the horizontal support member 20. This creates two open spaces 90 and 92 in the frame resulting in a lighter weight and reduced wind resistance once the unit is mounted on the utility pole. 
     In a similar way left 34 and right 38 diagonal support legs are also spaced apart at a mid-section 35 and 37 from the horizontal support member 20. This creates two additional open spaces 94 and 96 in the frame. 
     FIG. 4 illustrates a wire support member 100 having a wire trough 102 and watershed rings 104. The wire support member has an internally threaded hole so that it may be mounted onto insulator pins 12A, 12B, or 12C. FIG. 5 shows a larger sized wire support member 106 with the internally threaded hole 108 shown in broken lines. FIG. 6 shows an insulator protective cap 110 with threaded hole 112 in broken lines. 
     By the appropriate arrangement of insulator members 100, 106, and 110, the present invention enables the user to connect from single phase delivery to three phase delivery without having to completely rebuild the entire cross arm structure. In a single phase configuration two of the insulator pins are provided with wire support members 100 and 106 and the third pin is provided with a protective cap 110. In a three phase configuration all pins are provided with wire support members. 
     To convert from one configuration to another merely requires the user to remove a threaded cap and replace it with a threaded wire support member. In geographical regions where increased electrical utility demands are occurring the present invention considerably reduces the labor and cost to upgrade a system. 
     FIGS. 1A, 2A, 3A, 4A, 5A, and 6A illustrate an alternative embodiment of the present invention. As FIG. 1A shows the upper neck support is shorter and mounting holes 48A and 49A are moved inwardly along horizontal support arm. Pins 12A, 12B, and 12C are not tapered but are generally cylindrical threaded pins. The pins do not have the cylindrical base member 60 as is found with pins 12A, 12B, or 12C. 
     However, the structural arrangement of the arms 80A, 82A, and 20A and the legs 34A and 38A are essentially the same as those described in the first embodiment above. The insulators 100A, 106A, and 10A have the same functions as those described above. 
     Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. On the contrary, various modifications of the disclosed embodiments will become apparent to those skilled in the art upon reference to the description of the invention. It is therefore contemplated that the appended claims will cover such modifications, alternatives, and equivalents that fall within the true spirit and scope of the invention.