  We study how the presence of world-sheet currents affects the evolution of
cosmic string networks, and their impact on predictions for the cosmic
microwave background (CMB) anisotropies generated by these networks. We provide
a general description of string networks with currents and explicitly
investigate in detail two physically motivated examples: wiggly and
superconducting cosmic string networks. By using a modified version of the
CMBact code, we show quantitatively how the relevant network parameters in both
of these cases influence the predicted CMB signal. Our analysis suggests that
previous studies have overestimated the amplitude of the anisotropies for
wiggly strings. For superconducting strings the amplitude of the anisotropies
depends on parameters which presently are not well known - but which can be
measured in future high-resolution numerical simulations.
