Insulation in sheet form
The requirement in Clause 4.1.4.3 does not apply if the insulation is applied in thin sheet form, other than mica or similar scaly material, and
(a) for supplementary insulation, consists of at least two layers, provided that each of the layers withstands the electric strength test of Clause 8.4 for supplementary insulation; or
(b) for reinforced insulation, consists of at least three layers, provided that any two layers together withstand the electric strength test of Clause 8.4 for reinforced insulation.
Compliance is checked by inspection.