Electrical Resistance Tomography (ERT) has been widely accepted as a useful tool to visualize conductivity distributions. Traditional ERT systems use a scheme with current injection and voltage measurement to detect changes in conductivity in a region of interest. Such current injection is usually accomplished by the use of small metallic pin electrodes. As a consequence of the ‘soft-field’ feature of the electric field and the use of small pin electrodes, there exists an axial dispersion of the sensing field i.e. fringe effect. In consequence, the reconstructed images are distorted and hence they can only provide qualitative information of the conductivity distribution. An ERT system with voltage excitation and larger electrodes would reduce the distortion due to the fringe effect. In addition, the use of a voltage source instead of current reduces the complexity and cost of the implementation while increases the range of conductivities the ERT system is capable to image. In this work, the construction of an ERT system with voltage excitation is described. In addition, the impact of driven guards in an ERT sensor is studied.