How is AC conductor voltage drop typically calculated in practice?

• A. ΔV = I × Z, with length and temperature corrections.
• B. ΔV = I × Z^2.
• C. ΔV = V × I.
• D. ΔV = P / V.

Answer: (A)

In AC circuits the voltage drop along a conductor comes from the impedance the current encounters, not just pure resistance. The drop is found with Ohm’s law for AC: the drop is the current times the impedance, ΔV ≈ I × |Z| (using the magnitude of Z to get the size of the drop). Z combines resistance and reactance (Z = R + jX), so the drop depends on both how much resistance the conductor has and how much reactive effect its inductance and capacitance create. To apply this in practice you use the impedance per unit length of the conductor and multiply by the length, giving Z ≈ Z_per_length × L, then calculate ΔV = I × |Z|. Temperature matters because resistance rises with temperature, so you apply a correction to R: R(T) = R_ref × [1 + α (T − T_ref)]. Reactance can also play a role, but for many practical short runs the magnitude of IZ is a good overall indicator. If X is small, you can approximate ΔV ≈ I × R. The other formulas don’t describe how AC voltage drop arises and don’t give the correct relationship.