POLYPHASE INDUCTION MOTORS 



103 



BROWN AND SHARP WIRE TABLE 



Note. The system of sizes, known as the B. & S. gauge, represent a geo- 

 metric series between No. 4/0 and No. 36, and involve, therefore, large num- 

 bers of decimals for their exact expressions. In preparing the above table the 

 specifications of the American Society for Testing Materials, dated June 1, 

 1912, were taken into consideration. These provide that for soft wires the 

 permissible variation from nominal diameter shall be for wire 0.01 inch in 

 diameter and larger, 1% over or under. For wires less than 0.01 inch in 

 diameter, 0.1 mil over or under. For medium hard and hard wire 1% varia- 

 tion is allowed for wires 0.1 inch and larger, and 1 mil for smaller wires. In 

 expressing the size of such wires not more than three decimals of an inch shall 

 be used, namely, whole mils. The specifications further condemn the use of 

 large numbers of decimals in expressing the diameter of wires, and recom- 

 mend that actual diameters rather than gauge numbers be used. 



