This paper explains how the disputed energy oscillations associated with nonactive powers can be attributed to electromagnetic waves that travel back and forth between the transmission line's sending and receiving ends. Such waves "hug" the conductors and dwell in the dielectric that surrounds the conductors. The propagation of these energy waves and the density of their rate of flow may be observed with the help of Poynting Vector. This approach, based on the electromagnetic fields theory, explains the true physical mechanism of energy propagation in power systems and helps interpret correctly the power expressions in three-phase systems.