Voltage dips are one of the most recurrent types of power quality disturbances detectable in power systems. Root-cause analysis is important to identify opportunities for mitigation. In this paper, a recently proposed practical method to locate the source of voltage dips that requires only basic Power Quality measurements is refined, including, in particular, an improved solution for aggregating dip events and extended to the case of multi-level scenarios. The performance of this method is evaluated under different operating conditions using real-field data in a South African 66 kV/11 kV network.