A method performed by a data processing apparatus (104; 118), the method comprising: receiving, by the data processing apparatus (104; 118), 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 for communicating data via the power line network; determining, by the data processing apparatus (104; 118), 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; for communicating data via the power line network, identifying an endpoint that communicates over the at least one communications channel; determining that a set of the signal characteristic values matches one of a plurality a grid event signatures for the identified endpoint, each of the grid event signatures being indicative of a particular grid event, wherein the plurality of grid event signatures includes a respective grid event signature for each of a set of grid events including a capacitor bank failure, a power outage, and capacitor bank activation, and wherein determining that the set of signal characteristic values matches one of a plurality of grid event signatures comprises determining that the set of signal characteristic values matches a grid event signature for one of a capacitor bank failure, a power outage, or capacitor bank activation; and providing data that identify the endpoint and the particular grid event for the grid event signature that is matched by the set of monitored signal characteristics. receiving, by the data processing apparatus (104; 118), 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 for communicating data via the power line network; determining, by the data processing apparatus (104; 118), 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; for communicating data via the power line network, identifying an endpoint that communicates over the at least one communications channel; determining that a set of the signal characteristic values matches one of a plurality a grid event signatures for the identified endpoint, each of the grid event signatures being indicative of a particular grid event, wherein the plurality of grid event signatures includes a respective grid event signature for each of a set of grid events including a capacitor bank failure, a power outage, and capacitor bank activation, and wherein determining that the set of signal characteristic values matches one of a plurality of grid event signatures comprises determining that the set of signal characteristic values matches a grid event signature for one of a capacitor bank failure, a power outage, or capacitor bank activation; and wherein the plurality of grid event signatures includes a respective grid event signature for each of a set of grid events including a capacitor bank failure, a power outage, and capacitor bank activation, and wherein determining that the set of signal characteristic values matches one of a plurality of grid event signatures comprises determining that the set of signal characteristic values matches a grid event signature for one of a capacitor bank failure, a power outage, or capacitor bank activation; and providing data that identify the endpoint and the particular grid event for the grid event signature that is matched by the set of monitored signal characteristics.