Provides a test method for determining the extent to which electrotechnical products support mould growth and how any mould growth may affect the performance and other relevant properties of the product. Since mould growth conditions include high relative humidity, the test is applicable to electrotechnical products intended for transportation, storage and use under humid conditions over a period of some days at least. The main changes with respect to the previous edition are listed below: - Two test fungi replaced by two others - Concentration of the spores defined for each test fungus - Spores suspension in mineral salt solution additionally introduced - Pre-conditioning of the specimens by damp heat storage prescribed - Supersonic aerosolization of the spores suspension as the preferred inoculation method introduced - Duration of incubation reduced from 84 days to 56 days - Extent of mould growth grade 2 split into grade 2a and grade 2b - Detailed information on methods of inoculation given in Annex B - Annex E: flow-chart deleted