Apparatus for disaggregating a plurality of aggregated electrical devices that receive power via a same power node, the apparatus comprising: a memory having values of at least one power feature for each of the aggregated electrical devices that characterizes power consumption of the device; and a processor configured to: receive a measure of a value for the at least one power feature of node power distributed to the aggregated devices via the power node; determine an optimum probability mass function (PMF) based on the values for the at least one power feature for each of the electrical devices that is optimized to provide an optimum disaggregation state vector for the aggregated electrical devices that satisfies a predetermined criterion to provide a value for the at least one power feature that agrees with the received measure of the at least one power feature.