Specifies noise level limits in terms of sound power levels for rotating electrical machines from 1 kW (or kV.A) to 5500 kW (or kV.A), using methods of measurement in accordance with the ISO engineering method (ISO 1680/1) rather than the ISO survey method (ISO 1680/2). Explains the difference between the two methods, and gives the reasons for the specified choice. Does not consider the legal aspects of noise pollution but recognizes achievable noise levels of machines of standard design and the availability of supplementary means of noise attenuation where necessary. Provides guidance in the calculation of mean sound pressure levels at various distances from a machine.