[en] In toroidal experiments, such as Screw Pinches, Belt Pinches, and Reversed Field Pinches, with both toroidal and poloidal magnetic fields, quite complicated E-fields exist. For an appropriate design one should however, know what voltages occur between the various coils, the stabilizing shell, the plasma itself, the pumping stations, and diagnostic equipment. An attempt is made to give a systematic description of the voltages that develop between coils and objects placed inside them. Two types of coils are considered, one without an external return flux, analogous to the toroidal field coil; and one with external return flux, analogous to the poloidal field coil. Possible methods of grounding are discussed. The Appendix describes what voltages are to be expected in the ZT-40 Reversed-Field Pinch experiment under construction at the Los Alamos Scientific Laboratory