A disordered array of metal grains with large and random intergrain
conductances is studied within the one-loop accuracy renormalization group
approach. While at low level of disorder the dependence of conductivity on log
T is nonuniversal (it depends on details of the array's geometry), for strong
disorder this dependence is described by a universal nonlinear function, which
depends only on the array's dimensionality. In two dimensions this function is
found numerically. The dimensional crossover in granular films is discussed.Comment: 6 pages, 6 figures, submitted to JETP Letter