referred to are the assumptions used in computing the zero sequence impedances of circuits 7 and 8. The moduli of the vector expressions of So in these 2 cases, it may be noted, are not only of the same order of magnitude as those of the 3 field determinations, but their angular positions are such that they include within their phase difference of 9.5 degrees the angular positions of the 3 experimentally determined vectors (circuits 1, 2, and 3) The equiva¬lent ground return, therefore, would consist of at least, and possibly 2, sheaths of similar cables m parallel with the sheath of the faulted cable, and, as implied by the separations in the limiting assumptions, the paralleling sheath, or sheaths, would run in the same duct bank as the faulted cable. The calculations also indicate the extent to which the sheath of the faulted cable serves as a return path for the current. In a system of this land, where about half the current returns on the feeder’s own