412 PROTECTIVE MEASURE: DOUBLE OR REINFORCED INSULATION.

412.1.3 Where this protective measure is to be used as the sole protective measure ( i.e. where a whole installation or circuit is intended to consist entirely of equipment with double insulation or reinforced insulation ), it shall be verified that the installation or circuit concerned will be under the effective supervision in normal use so that no change is made that would impair the effectiveness of the protective measure. This protective measure shall not therefore be applied to any circuit that includes a socket-outlet, luminair supporting coupler (LSC), device for connecting a luminair (DCL) or cable coupler, or where a user may change items of equipment without authorization.