The invention discloses an electrical sensor for a two-wire power cable. The sensor includes: a flexible substrate joined onto the power cable or the protective jacket thereon; an inductive coil formed on the flexible substrate; a pair of metal electrodes formed on the flexible substrate and at the opposite sides of the power cable, respectively; and a readout circuit formed on the flexible substrate, electrically connected to the inductive coil so as to measure the current in the power cable, and electrically connected to the metal electrodes so as to measure the voltage in the power cable.