  A composite conductive material, which consists of fibers of a high
conductivity in a matrix of low conductivity, is discussed. The effective
conductivity of the system considered is calculated in Clausius-Mossotti
approximation. Obtained relationships can be used to calculate the conductivity
of a matrix, using experimentally measured parameters. Electric fields in the
matrix and the inclusions are calculated. It is shown that the field in a
low-conductivity matrix can be much higher than the external applied one.
