INSULATION TEST EQUIPMENT FOR LOCAL CROSSBAR SYSTEMS 631 



distribution after the reconditioning was completed. The lower curve 

 can be considered as representative of an outside plant in good condition 

 as of the year 1940 when rapid hne insulation testing was not yet used. 

 Since that time, a considerable number of improvements leading to 

 better insulation resistance characteristics have been made in outside 

 plant items, such as drop wire and cable terminals, and a higher av- 

 erage insulation resistance would currently obtain. However, during wet 

 weather, an undesirably large number of lines would still be closer than 

 desired to the design limit. 



MAINTENANCE WITHOUT RAPID LINE INSULATION TESTING 



It may appear at first sight that the per cent of lines near or below 

 the design limit is so small as to be unworthy of particular notice. How- 

 ever, an examination of this from a maintenance standpoint ^vill prove 

 otherwise. The testing of lines reported in trouble and dispatching of 

 craftsmen on the outside to make repairs are handled from a local test 

 center which on the average serves about 50,000 stations. There will be 

 about six local test desk positions manned to do the testing and dis- 



o 



2 

 < 



(OUJ 

 UJoC 



z 



CL Z 



uj m 

 Q.> 



>z 



5^. 



10' 



8 1d8 



Fig. 2 



2 34568 ^0^ 2 3456 



INSULATION RESISTANCE IN OHMS 



Wet weather tests — insulation resistance by types of Outside Plant. 



