This International Standard specifies general and safety requirements for electronic step-down convertors for use on d.c. supplies up to 250 V or a.c. supplies up to 1 000 V at 50 Hz or 60 Hz and rated output voltage£50 V r.m.s. at a frequency deviating from the supply frequency or£50 2 Vunsmoothed d.c. between conductors or between any conductor and earth, associated with tungsten-halogen lamps as specified in IEC 60357 and other filament lamps.NOTE – The limit of 50 V rated output voltage is in accordance with Band 1 of IEC 60449.Particular requirements for electronic step-down convertors with means of protection against overheating are given in annex B.Particular requirements for stationary independent SELV convertors, which are part of the wiring in installations, are given in annex C.Plug-in convertors, being part of the luminaire, are covered as built-in convertors together with the additional requirements of the luminaire standard.NOTE – These proposals have also been submitted to SC 14D for introduction in IEC 60742.