Soo 



INSTALLATION OF ARC LAMPS 



[Cn. XIII 



INSTALLATION OF AN ARC LAMP FOR PROJECTION 



693. In the first place it is necessary to know the maximum 

 amperage to be used for the projection. The wiring, the fuses and 

 the ballast (rheostat, inductor, etc.) must be adapted to this 

 maximum current. 



If the installation is adequate for the highest current that may 

 need to be used, it will of course be adequate for any smaller 

 current. 



For drawing, and much of the ordinary magic lantern work, the 

 current varies from 5 to 15 amperes, and if the installation were 

 for such work alone, wiring and accessory apparatus which is safe 

 for 15 amperes would suffice. If, on the other hand, the line were 

 to be used for large halls also, and especially for opaque projection 

 (Ch. VII), then the wiring and accessory apparatus would reed to 

 have a maximum capacity of 50 to 60 amperes. For moving pic- 

 tures, the line should safely carry a maximum of 75 amperes, or 

 finally if kinemacolor moving pictures are to be shown in a large 

 hall, the wiring and accessory apparatus must be adapted for an 

 amperage of 100 to 200. 



The size of solid wires for different currents is given in the follow- 

 ing table : 



694. Table of allowable carrying capacity of single copper 

 wires of 98% conductivity.* 



AMERICAN INSTITUTE OF ELECTRICAL ENGINEERS 



*From the 1913 National Electrical Code, 18, pp 32-33. 



