IEC 60667-1:2020 gives the definitions and general requirements for vulcanized fibre sheets for electrical purposes. Materials made by combining with an adhesive several thicknesses of vulcanized fibre are not covered by this document. Materials that conform to this specification meet established levels of performance. However, the selection of a material by a user for a specific application is based on the actual requirements necessary for adequate performance in that application and not based on this specification alone. Safety warning: it is the responsibility of the user of the methods contained or referred to in this document to ensure that they are used in a safe manner. This second edition cancels and replaces the first edition published in 1980. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: deletion of "corrugated, round rods, and round tubes" from the Scope; types A, B and C replaced by general and fishpaper types and addition of a symbol for each type in the classification; addition of white, blue, brown, and addition of a symbol for each colour; deletion of the thickness of 15,0 mm, the length, the mass and the dimension of rolls from the general requirements; addition of the manufacturer's name, trademark (if any), nominal thickness, manufacture date, and lot number in the conditions of supply.