Rubber materials are widely used in many industries, either as the major material or forming a part of the product, because of their unique physical properties which can be tailored by compounding to match the particular requirements of the product specification. Although rubbers are generally regarded as insulating materials, they can be made electrically conductive or dissipative by compounding with a certain amount of carbon black or ionizable ingredients. Hence, the range of electrical resistance to be measured is very wide, it is difficult, however, to obtain high accuracy for measurements in the high-resistance range due to number of factors.