704 



BELL SYSTEM TECHNICAL JOURNAL 



As to the inside surfaces the situation is somewhat different. These 

 are protected from direct rainfall and become wet by splashing, con- 

 densation, creepage, and by moisture carried by air currents. 



To prevent splashing from the crossarm it might appear desirable 

 to provide the insulator with a wide flaring kind of shed but experience 

 has shown that such sheds may be quite ineffective or even detrimental. 

 It will be convenient to discuss the action of one type of shed later. 



Fig. 6 — Experimental design with short corrugated skirt (C. P.) mounted on 



standard steel pin. 



It has been found preferable to employ an insulator of small diameter. 

 The effects of the splashing can be reduced by placing the insulator 

 higher from the crossarm and by restricting the area of the opening 

 between the pin and the insulator where the rising drops of water must 

 enter. 



These drops may readily rise a foot or more as casual observations 

 show. To raise an insulator completely out of range obviously would 

 lead to a cumbersome and mechanically unsatisfactory construction. 

 However, some advantage may be had in elevating the insulator. 



For example, consider Fig. 7 which shows the insulator of Fig. 6 

 mounted on a long pin. This pin, which was designed for another 

 purpose, has an enlarged section which restricts the area between the 



