with reference now to the fig and in particular to fig1 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 . fig2 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 fig2 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 fig3 ). the base member 60 may receive a sleeve insert 50 as appropriate . fig3 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 , fig3 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 . fig4 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 . fig5 shows a larger sized wire support member 106 with the internally threaded hole 108 shown in broken lines . fig6 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 . fig1 a , 2a , 3a , 4a , 5a , and 6a illustrate an alternative embodiment of the present invention . as fig1 a 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 .