610 



ELECTRICAL EQUIPMENT 



roof of the station or on suitable brackets on the outside wall of the 

 station. They should be so located that the pipe and lever, by 

 which they are operated, can be brought down in a place convenient 

 for the operator and if possible where he can observe the arcing 

 at the horns during discharge. 



With lightning arrester equipments for higher voltages there 

 is, however, a growing tendency to install the entire equipment 

 outdoors (Fig. 389). Any objection to installing arrester tanks 

 out of doors comes, of course, from the increased liability of freez- 

 ing the electrolyte in cold weather and the abnormal film dis- 



FIG. 389. Outdoor Lightning Arrester Installation. 



solution when exposed to the sun on hot days. This, therefore, 

 has a bearing on the electrolyte which should be used. These 

 are two kinds, both of which freeze at about 20 F. One will, 

 however, better withstand severe winter temperatures and the 

 other excessive summer temperatures. Should, therefore, for 

 example, the operating temperature during summer exceed 100 F., 

 with freezing temperature in winter, it would be preferable to 

 use the electrolyte for the warm weather and provide means 

 to prevent freezing during the winter months. The electrolyte 

 may not be injured by freezing, but when frozen the internal 

 resistance of the arrester is considerably increased and hence 



