(nitpicking) That's correct if you take into account the skin effect when computing the cross-section area (or if you design your transmission line to avoid it.

(nitpicking) That's correct if you take into account the skin effect when computing the cross-section area (or if you design your transmission line to avoid it. Better solution). But at 50/60 Hz, it's negligible (the "skin depth" of copper at these frequencies is around 9mm)