To keep a high level of power quality, Distribution System Operators (DSOs) must keep harmonic voltage levels under limits specified in standards. These harmonic voltages are due to non-linear equipment connected inside installations, which inject harmonic currents into public networks. In order to apply emission limits per installation, DSOs need to have an accurate and reliable indicator to assess the harmonic emissions of an installation. In this paper, a comparative analysis of two definitions for assessing the harmonic emissions of installations is presented. Their respective advantages and drawbacks are pointed out.