IEC 61050 Ed. 1.0 b:1991

Applicable to independent and built-in single-phase transformers with separate input and output windings, for use on a.c. supply up to 1000 V at 50 Hz or 60 Hz, to supply and stabilize cold cathode tubular lamps (or assemblies of such lamps) having a no-load rated output voltage exceeding 1000 V but not exceeding 10 000 V and intended for lighting and for electric advertising signs, light signals and similar purposes.