An electrical conductor and in particular a conductor bar of an electrical machine, particularly a generator or transformer, in which an optical measuring device can be integrally arranged. A measuring unit includes an electrical conductor and an optical measuring device arranged in the conductor, and a production method for producing such an electrical conductor is described. The electrical conductor (10), having a conductor cross section and also an extent in the conductor longitudinal direction, includes a recess (11, 12, 13) in the conductor longitudinal direction at least along a section of the conductor, for integrated arrangement of a signal conductor, in particular an optical waveguide.