1. A computer-implemented method for labeling devices in a building, the method comprising: measuring an electrical signal from the building, wherein the electrical signal powers a plurality of devices; computing a plurality of features from the measured electrical signal; computing a plurality of scores using a plurality of mathematical models and the plurality of features, wherein (i) the plurality of mathematical models comprises a first mathematical model corresponding to a first class of devices and (ii) the plurality of scores comprises a first score computed using the first mathematical model and the plurality of features; selecting the first mathematical model using the plurality of scores; using the first mathematical model to obtain first information about the first class of devices; causing the first information to be presented to a user; prompting the user to provide second information about a first device in the building, wherein the first device corresponds to the first class of devices; receiving the second information from the user; associating the first device with a label using the second information; obtaining a second mathematical model for the first device using the second information or the label; and associating the second mathematical model with the first device.