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If an eagle or other bird were to land on the obstructed side of the cross- <br />arm, contact between the phase and ground would be prevented by the separa- <br />tion of the two wires by about 5 feet vertically. In addition, contact is <br />further prevented by the fact that the ground wire runs on the opposite side <br />of the pole from the phase wire on top of the cross atm. Contact between two <br />phases is also extremely unlikely due to the approximate 3 feet vertical <br />separation of the wires. <br />2) The Stacked Structure is represented in Figure 3.8-6 and shows the three <br />phases mounted one above the other in a stacked fashion with a ground wire <br />mounted at the top of the pole. The separation of phases and ground is a <br />minimum of eight feet so there is no chance for power contact to be made. <br />There is a lightning rod at the top of the pole with an insulated wire run- <br />Wing down the pole to the ground. <br />3) The Switch Structure is represented in Figure 3.8-8 and is a modified Tangent <br />Structure, to accommodate a switch. The Tangent Structure is discussed in <br />paragraph 4. This structure may be erected with the contacts on the upper <br />crossarm rotated in toward the pole or away from the pole. The groundwire on <br />this structure is mounted 6 inches below the top of the pole and again, there <br />is a lightning rod with an insulated wire running Erom [he rod to the <br />ground. The top crossarm is mounted 7'-4" below the Cop of the pole, and it <br />is assumed that an eagle or other large bird would land on the top of the <br />pole or on the unobstructed end of the upper crossarm. If an eagle were Co <br />land on the end of the crossarm having the phase mounted on it, there would <br />be no chance of contact with an average wingspan less than 90 inches. Ninety <br />inches is the diagonal distance between the closed switch mounted in the out- <br />ward tilted position and the ground wire at the top of the pole. With the <br />switch mounted in the position rotated toward the pole, the diagonal distance <br />is reduced to 66.2", but there would only be 28 inches between the phase and <br />the pole horizontally. It would be highly unlikely that a large bird would <br />choose to Land in this area. In addition, there is a 60-inch vertical <br />separation between Che phase wire and the ground wire leaving the most remote <br />possibility contact would he made. <br /> <br />4-163 <br />~~ElIIS~Q rEB 1 aj `~7 <br />