The method of analysis first suggested by Bangand Louisand later extended by Clarkand Shanklin was applied to this particular case, and the carrying capacity for the cable as determine din this manner was found to agree closely with the results of experience. The method was therefore extended so as to determine the law connecting the size of conductor, the dielectric loss and the carrying capacity. Curves and charts are presented showing the carrying capacity of all sizes of three-conductor cables above 100,000 Cir. mils and of the entire commercial range of dielectric losses. These results were then compared with the operating records of a transmission system having cables ranging in size from No.0 0 A.W.G. to 500,000 Cir. Mils and with operating voltages of 9, 12, 20 and 22 kv. The results of this comparison appear to indicate that practically all failures on these transmission lines, which were not due to external damage to the leads heath, were due to the cables being loaded beyond their safe carrying capacity, and that the dielectric losses had not been given proper consideration in determining the carrying capacity of these cables.