Deals with conducted disturbances in the frequency range up to 10 kHz with an extension for mains signalling systems. Gives numerical compatibility levels for low voltage a.c. distribution systems with a nominal voltage up to 240 V a.c. single-phase or 415 V, three-phase and a nominal frequency of 50 Hz or 60 Hz. Does not deal with the application of compatibility levels to assess, for example the allowable interference emission from specific items of equipment or installations.