The invention relates an apparatus that can be electrically operated via a mains voltage connection, in particular without an earth conductor, comprising a live element and an applied part, wherein the applied part is insulated by means of a basic insulation with respect to the live part. An insulation monitoring device is provided, which monitors the quality of the basic insulation of the applied part with respect to the live part. The invention further relates to a medical apparatus having a heating module for heating a medical fluid, wherein the heating module comprises a heating element having a heating coil arranged on a first ceramics layer, wherein the heating element is arranged on a second ceramics layer, wherein the second ceramics layer advantageously forms a heating plate of the heating module.
