The conditions under which more than one stable electric discharge can be operated so as to interact electromagnetically have been investigated with arc discharges at currents of 10-2100 A in air and argon at atmospheric pressure, and with glow discharges at currents of the order of 10 mA-2.4 A at pressures from 100 Pa to atmospheric pressure in air, argon and CO2laser gas mixtures. A wide variety of electrode configurations are possible, many of which have not been described before. Operation with parallel (attracting) discharges and antiparallel (repelling) discharges from the same and separate supplies is described and the conditions for stable operation analysed. The principles are applicable to almost all uses of electric discharges, including high-current water-cooled electrodes for use in arc furnaces and plasma furnaces; low- and high-pressure discharge lamps, CW gas lasers and spark plugs.