Wire Calculations.—In the calculation of alternating current circuits, the two chief factors which make the computation different from that for direct current circuits, is induction and power factor. The first depends on the frequency, and physical condition of the circuit, and the second upon the character of the load.
Ques. Under what conditions may inductance be neglected?
Figs. 2,696 to 2,698.—Example of wiring showing where inductance is negligible, and where it must be considered in wire calculations.
Ans. In cases where the wires of a circuit are not spaced over an inch apart, or in conduit work, where both wires are in the same conduit.
Under these conditions the calculation is the same as for direct current after making proper allowance for power factor.
Ques. Under what conditions must induction be considered?
Ans. On exposed circuits with wires separated several inches, particularly in the case of large wires.
Sizes of Wire.—The size of wire for any alternating circuit may be determined by slightly modifying the formula used in direct current work, and which, as derived in Guide No. 4, page 748, is