A STUDY OF TELEPHONE LINE INSULATORS 



705 



pin and the insulator. Ttie improved performance is, therefore, 

 the result of two effects: one, that of elevating the insulator; the other, 

 that of restricting the area between the pin and the insulator. 



An attempt was made to separate these effects by providing a third 

 set-up in which the insulator is mounted on the pin of Fig. 6, this short 

 pin being supplied with a rubber washer of the proper size and location 

 to simulate the enlarged section of the long pin. 



^^ ^ 



Fig. 7 — C. P. design on long steel pin with baffle. 



The relative performance of these three arrangements is given in Fig. 

 8 where 5 stands for short pin; SB, short pin with baffle; and LB long 

 pin with baffle. These results were obtained during a hard shower 

 within a month after the installation of the rubber washers and give 

 some idea of the effectiveness of the two expedients. 



In discussing the influence of insulator design on this type of leakage 

 the question naturally arises as to the part played by the pin on which 

 the insulator is mounted. 



Wood pins of the type commonly employed on telephone lines are 



