Frequency-dependent network impedance (FdNI) is a crucial aspect of electromagnetic compatibility coordination. In low voltage (LV) networks, reference impedance characteristics are commonly used to represent FdNI in the frequency range of 2-150 kHz. These characteristics are essential for a credible regulatory regime, but they are based on studies conducted several decades ago. This paper presents the results of a comprehensive study that aims to validate the suitability of reference impedances for representing the FdNI in current public LV networks. The study draws conclusions about the typical characteristics of the FdNI, examines its dependence on closely connected electrical appliances, and evaluates its time variability based on an extensive measurement campaign conducted in Germany, Spain and the United Kingdom.