Transmitting electrical current to the subsurface can create special considerations. Successful application of electromagnetic heating often requires a multi-disciplinary approach combining electric engineering and petroleum engineering. To assist petroleum engineers considering this approach, this article identifies some of the issues that an electrical engineer might normally anticipate and address. In most practical situations, we are concerned with fields that vary periodically in time (the sinusoidal steady state generally). In these cases the electrical phenomena are properly described by Maxwell equations in terms of complex vector field intensities of electric and magnetic fields (E and H); complex vector field electric, magnetic, and current densities (D,B,J); complex charge concentrations (ρc); and complex material parameters: conductivity, permittivity, and permeability (σ, ε, μM).