Electrophoretic deposition is a versatile coating technique for poorly conducting materials on sufficiently well conducting substrates, e.g. oxides are deposited on highly conductive carbon composites covered by a moderately conductive SiC layer. A numerical simulation based on the solution of the Laplace equation is applied to different geometries. The calculations yield potential distributions and current densities, which are directly connected with the oxide mass deposited on the samples. The calculated results are compared with the experimentally obtained values and satisfactory agreement is found. Further, the model reproduces the main features of the current-voltage relation.