According to one aspect, embodiments of the invention provide a system monitor for a load center comprising a current sensor configured to be coupled to a circuit branch within the load center and to produce a measurement signal having a level related to a current level of the circuit branch, a sensor circuit coupled to the current sensor and removably coupled to a terminal, the sensor circuit configured to provide the measurement signal to the terminal, and a controller coupled to the terminal and configured to monitor signals at the terminal, wherein the controller is further configured to detect disconnection of the current sensor from the terminal based on a signal level at the terminal.