A method for monitoring lightning protection equipment comprising an earthing line (1) by measuring the electric current or lightning current flowing through the earthing line. The measurement is obtained by means of a self-contained magnetic circuit (2) around the earthing line, and an electrical circuit with a winding (5) provided around the magnetic circuit so that a lightning current flowing through the earthing line generates an induced current in said winding, said magnetic circuit comprising a solid magnetic core (3) with at least one break in the magnetic circuit, which break is filled with a non-magnetic material.