Insulation in thin sheet materials is permitted for SUPPLEMENTARY INSULATION and REINFORCED
INSULATION (see Figure F.15), irrespective of the distance through insulation, provided that all of
the following apply:
– two or more layers are used;
– the insulation is within the equipment ENCLOSURE;
– the insulation is not subject to handling or abrasion during OPERATOR servicing; and
– the requirements and tests of 2.10.5.7 (for separable layers) or 2.10.5.8 (for nonseparable
layers) are met.
For insulation in separable thin sheet layers, in addition to the requirements of 2.10.5.6,
– SUPPLEMENTARY INSULATION shall consist of at least two layers of material, each of which will pass the electric strength test for SUPPLEMENTARY INSULATION; or