A wireless current sensor for measuring an electrical current flowing in an electrical conductor comprising a current transformer including a core arranged around the electrical conductor and forming a primary of the current transformer, and a winding around the core and forming a secondary of the current transformer in order to retrieve an electrical power when an electrical current flows in the electrical conductor, and an electronic circuit connected to the secondary of the current transformer, the electronic circuit including means for storing the generated electrical power, means for measuring the electrical current flowing in the electrical conductor, and a wireless data transceiver coupled to a microcontroller to send the measurement data.