Electrohydrodynamic processes in two-phase immiscible liquids include electrical deformation and coalescence. The latter are primary phenomena in electrostatic phase separation and many other technologies, yet represent a rather challenging issue for numerical simulation, especially when electrical conductivities of phases differ significantly. There are several papers in the literature where computations are distorted with a charge “escape” problem when the space charge emerges far from the interface. The article provides a thorough analysis of the issue and suggests a modification of the numerical model. The key idea is in changing the dependence of the electrical conductivity on fluid volume fraction from a linear to the exponential one. To verify the approach, original experimental data were acquired that lacks typical flaws and are suitable for a quantitative comparison. The use of the data confirms the correctness of the modified numerical model.