572 ELECTRICAL EQUIPMENT 



is similar to bringing one out of a transformer. It is usually 

 best to bring the high-tension conductors out through the roof, 

 although in some cases a wall outlet may be advantageous. No 

 fixed rule can be made in this respect since the method depends on 

 the particular layout, arrangement of buses, disconnecting switches, 

 and lightning arresters. For pressures of 100,000 and higher, the 



FIG. 363. Low-tension Bus Compartments. 



weight of the outlet bushings and their great size as well as the 

 required ground clearance from steel must be taken into consid- 

 eration when designing the roof. Figs. 366 and 367 show two 

 typical designs of line entrances. 



Owing to the cost of providing suitable buildings for trans- 

 formers and switching equipments operating at very high poten- 

 tials, the question of placing this apparatus outdoors is one that is 

 receiving a great deal of attention. Numerous transformer and 



