The four‐point alternating current potential drop (ACPD) method has the potential to evaluate different depths of case hardening in steel. The potential drop was measured on a series of induction‐hardened and carburized steel rod samples. It was shown that four‐point ACPD is a promising technique for distinguishing between different depths of case hardening. Especially in the low‐frequency range of the real part of the normalized impedance, there is very good distinction between different case depths of the samples.