A self-contained wireless current sensor applied for two-wire zip-cords is proposed in this paper, which consists of a Hall sensor, a wireless module, and an energy harvester along with the power management circuit. The energy harvester is constructed from a current transformer, where an EE-type magnetic core with two arms is specially designed by making a slit in one arm to produce unsymmetric field distributions: the field with low flux density is used for sensing and that with higher flux density for energy harvesting. In the energy scavenging operation, the sensor can generate 4.3 $\mu \text{W}$ with a 217 $\Omega $ load resistor under 1 A zip-cord carrying current and supply power for the off-shelf Zig-bee nRF24LE1 wireless module to send one data for a time duration of about 5 min. In current-sensing operation, the sensor exhibits a sensitivity of 0.85 mV/A with a sensed current ranging from 1 A to 130 A.