TREE-LINE CONSTRUCTION 



71 



perly made it may be found that the ties pull loose under the weight of the line wire 

 alone. This must, of course, be avoided and the ties so made that they will not only 

 support the wire but also withstand the shock of falling trees up to the point where it 

 threatens to break the line. 



Fig-. 32 Split tree insulator attachment and crosstie 



6 CROSSTIE 



Fig. 32 A illustrates a complete crosstie with a No. 9 wire runing through the in- 

 sulator. Such >a tie should be used wherever it is desired to prevent the wire from run- 

 ning back after breakage of the main line. It should be made of No. 12 wire and be 

 from 20 to 25 in. long. This tie is usually preferable to the insulator and bracket dead- 

 end, in that it lessens the chance of the main line being jerked by heavy winds. 



The line should be stayed at the top of hills or the beginning of steep slopes. It is 

 not necessary to stay it on comparatively level ground if spans are properly equalized. 



The use of crossties should be avoided as much as possible. Perfect equalization 

 of spans will enable this to be accomplished in any but mountainous country. 



7 DEAD-ENDING 



So far as is practicable lines should be dead-ended and poles set and .braced for 

 that purpose. One or, if necessary, two brackets set close together may be used, the 

 method of fastening wire being illustrated in Figs. 24 and 25. When dead-ending on 

 trees the bracket-and-insulator method is not desirable, but instead the No. 500 white 

 strain insulator attached to the tree by four to six wraps of standard galvanized strand 

 should be used. The tree should be protected by four shims or cleats of wood. This 

 method is illustrated in Fig 33. 



Dead-ends should be used in the following situations: 



(1) At terminals of lines 



(2) At the ends of all extra long spans 



(3) At the tops of all long stretches of line, or steep slopes where the standard 

 crosstie is not adequate to stand the strain. 



