INDUCTIVE LOADING FOR TELEPHONE FACILITIES 



729 



usually was design flexibility in proportioning the case heights and the 

 cross-section dimensions to be approximately optimum for most efficient 



Fig. 27— Exchange area loading installation in side street auxiliary loading vault. In 

 congested areas, space limitations frequently require the installation of underground 

 cable loading coils in an auxiliary loading vault located in a side street near its intersec- 

 tion with the street under which the main cable conduit system is laid. Extensions of the 

 case stub cables carry the coil terminal leads to the main cable splices. At time of photo- 

 graph, a total of 18 cases containing a total of 7283 coils were installed in this auxiliary 

 vault. Six cases had 303 or 304 coils, and 12 cases had 455 or 456 coils. The 18 cases in- 

 clude 2 cast iron cases, 5 rectangular welded steel cases, and 1 1 tubular, thin steel cases. 

 The individual coil codes are Nos. 612, 632 and 643; 92% have 88 mh inductance, the 

 remainder being 135 mh coils. 27% have permalloy cores; the remaining 73% have molyb- 

 denum-permalloy cores and formex insulated windings. This figure shows the far end of 

 the loading vault where 14 cases are placed. Several tubular steel cases are hidden by 

 larger cases in foreground. 



use of the available mounting and splicing-space in the loading manholes, 

 subject of course to the manhole-opening Umitations previously mentioned. 



