A method for verifying interconnection of a PSE and PD with 4-pair PoE capabilities includes performing a first classification event on first and second pairs, respectively, and detecting a first predetermined class current on first and second sets of twisted pairs, respectively. The method includes performing a second classification event on first and second pairs, respectively, and detecting first and second predetermined class currents on first and second pairs, respectively. After expiration of a first variable delay period related to a first pseudo-random variable of the PSE, the method includes performing a third classification event on the first pair and detecting a first derived class current on the first pair. After expiration of a second variable delay period related to a second pseudo-random variable of the PD, the method includes performing the third classification event on the second pair and detecting a second derived class current on the second pair.