Replacement: This part of IEC 60519 is applicable to indirect resistance heating equipment for the heating and melting of glass, operating in voltage bands 1 and 2. These particular requirements also apply to equipment for direct resistance heating and melting of glass by means of current introduced by electrodes passing through the charge to be heated. The object of this standard is the determination of safety requirements for both indirect and direct resistance heating equipment for the heating and melting of glass, which is energized with d.c. voltage or with single-phase or multiphase a.c. voltage of frequency up to 60 Hz. NOTE Extraction of liquid glass or a similar material at the extraction point is part of the production process and does not constitute part of the operation of the electroheat equipment. The standard covers the safety aspects of electrical parts also in the case when electrical heating is combined with other means of heating, for example liquid fuel heating. These requirements do not apply to equipment for direct resistance heating, where, owing to the technology used, IEC 60519-3, IEC 60519-4, IEC 60519-8 are applicable.