This paper discusses the distinction between the harmonic currents that have a destructive effect and those that have a constructive effect on the voltage quality. Most standards allocate some limits for the harmonic current magnitude at the point of common coupling (PCC) to restrict the harmonic voltage at the PCC. This paper aims to answer ”whether all kinds of harmonic currents are destructive to the voltage quality and should be restricted to reach a better voltage quality.” The results of this paper show that in many cases, despite a high harmonic current at the PCC, the customer decreases the harmonic voltage at the PCC and, subsequently, improves the voltage quality. An example of such situations could be connecting a customer with a passive or active harmonic filter to a grid with a high background harmonic distortion. Therefore, restriction of harmonic current at the PCC does not necessarily result in a better voltage quality. This paper proposes a parameter to distinguish the constructive harmonic currents from the destructive ones.