Abstract: An apparatus for electrical current measurement. The apparatus may include a power input such as a current transformer that can be magnetically coupled to a line being measured. The apparatus may also include an energy harvesting circuit to parasitically harvest energy from the current transformer and an energy metering circuit to measure the current on the line. A controller can control the switching of a dynamic switch between an energy harvesting mode and an energy metering mode. The apparatus may also include a wireless transceiver. A plurality of these apparatuses may be combined into a network of devices to relay information from multiple current meters to a data concentrator and ultimately the Internet.