Since the second World War, this has been the standard furnace for melting steel in large quantities. Typical Capacities are 80 to 120 Tonnes. They were generally used as direct replacements for Siemens open hearth furnaces.

Low voltage, high current electricity arcs between three large electrodes hung from the lid of the furnace and the metal on the furnace hearth. This produces very intense heating in the centre of the furnace, in a similar way to arc welding. The heating can be very accurately controlled and as there are no 'products of combustion' (smoke and flame) within the furnace high quality steels are easily produced.