Abstract: A three-phase current sensor for measuring currents (IPH1, IPH2, IPH3) running in three conductors of a three-phase conductor system comprises a first magnetic measuring device (D1) and a second magnetic measuring device (D3). Each magnetic measuring device comprises a magnetic circuit provided with at least two interleaf gaps and a magnetic field sensor arranged in each interleaf gap. The magnetic measuring devices (D1, D3) are positioned on both sides of a central conductor or cavity, thereby enabling a central conductor to be inserted in such a way that one of three phases of the conductor system is formed.