This paper refers to electromagnetic field propagation around high-current circuits. The effects of its influence on conducting bodies that are seals and casings of electric devices are discussed. These barriers which are the constructional parts are made of ferromagnetic materials – good absorbers of energy transformed into heat in their structures. Intensity of absorbance depends on the distance between the barrier and source of radiant energy. Limitation of diffusing energy by absorbing it requires a high accuracy quantitative analysis to assure a high value of absorption coefficient and optimal power density of heat sources. The analysis results of basic geometries are shown.