The prediction of the conductivity of a random distribution of spheres in a continuum of different material is addressed in this work. The approach of Ohm’s law based on the unit cell is the starting point. Firstly, it is shown that the approach is compatible with the Fourier law approach which until now was considered irreconcilable. It is then demonstrated how one may use this result to model non-Maxwell interactions and thereby arrive at an equation for the conductivity of disperse media which predicts the property simply and in a physically clear fashion. Comparisons are made with existing models. The new equation is easy to use and can accommodate extensions to account for secondary effects.