A conductor, especially a conductor for measuring bio-electric signals occurring in an MRI environment, which comprises an electrically conductive part made of a non-metal material and a sheath part arranged over it. To produce a light and flexible conductor, the impedance of the conductive part is in the range of 5 to 300 kilo-ohm. The sheath part is arranged to endure a required voltage and the conductor comprises a support part which is made of a substantially inelastic material.