A wireless electric power sensing device can include a communication unit configured to communicate with an external device; a measuring unit configured to measure power consumption information corresponding to a plurality of devices located within a target space; and a central control unit configured to detect a point in time when one or more square waves are included in the power consumption information, determine reactive power based the power consumption information, identify an electric heating device from among the plurality of devices within the target space based on a rate of change in the reactive power, determine when an operation time of the electric heating device exceeds a predetermined amount of time based on a change in the power consumption information, and in response to the operation time of the of the electric heating device exceeding the predetermined amount of time, transmit, via the communication unit, identification information for the electric heating device and information about the operation time of the electric heating device to the external device.