Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for detecting grid events. In one aspect, a method includes receiving signal characteristic data that specify signal characteristic values for signals that are received over each of a plurality of communications channels of a power line communications network. A determination is made that the signal characteristic values for the signals that are received over at least one of the communications channels are outside of a baseline signal value range. An endpoint that communicates over the at least one communications channel is identified, and a determination is made that a set of the signal characteristic values for the identified endpoint matches one of a plurality a grid event signatures for the identified endpoint. Data that identify the endpoint and a particular grid event that is represented by the matched grid event signature are provided.