This part of IEC 60667 gives requirements for vulcanized fibre sheets for electrical purposes. Material made by combining with an adhesive several thicknesses of vulcanized fibre is not covered by this standard. Materials which conform to this specification meet established levels of performance. However, the selection of a material by a user for a specific application should be 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.