This part of IEC 61249 gives requirements for properties of phenolic cellulose paper, reinforced copper-clad laminated sheets of high electrical grade in thicknesses of 0,8 mm to 3,2 mm. This standard covers materials with different requirements on flammability and are designated according to the following: Material 61249-2-2-1: general purpose grade, requirement on flammability not specified (see 7.3.2); Material 61249-2-2-2: material of defined flammability (horizontal burning test) (see 7.3.2); Material 61249-2-2-3: material of defined flammability (vertical burning test) (see 7.3.3). These grades of material cover one of two flammability requirements, designated as FV0 or FV1, and shown in Table 9. Some property requirements may have several classes of performance. The class desired needs to be specified on the purchase order, otherwise the default class of material may be supplied