APPENDIX G USEFUL TABLES 



223 



Brown & Sharpe Gauge. The United States standard for wires for electrical 

 purposes. 



Law of the Brown & Sharpe Gauge. The diameters of wires on the B. & S. 

 gauge are obtained from the geometric series in which No. 0000=0.4600 inch and 

 No. 36= -005 inch, the nearest fourth significant figure being retained in the 

 areas and diameters so deduced. 



Let n == gauge number (0000 = - 3; 000 == 2; 00 = - 1). 



d == cKameter of wire in inches. 

 Then d = 0-3249 



1-128* 



Sheathing core. The number (N) of sheathing wires having a diameter (d) 

 which will cover a core having a diameter (-D) is 



N = 



D+d 



TABLE 4 TENSILE STRENGTH OF BARE COPPER WIRE 



The strength of soft copper wire varies from 32,000 to 36,000 pounds per square 

 inch, and of hard copper wire from 45,000 to 68,000 pound's per square inch, accord- 

 ing to the degree of hardness. 



The above table is calculated for 34,000 pounds for soft wire and 60,000 pounds 

 for hard wire, except for some of the larger sizes, where the breaking weight per 

 square inch is taken at 50,000 pounds for 0000, 000, and 00, 55,000 for 0, and 

 57,000 pounds for 1. 



TABLE 5 PROPERTIES OF HARD-DRAWN COPPER TELEPHONE AND TELEGRAPH 



WIRE 



