IEC 60335-2-106:2007

Deals with the safety of heating units to heat the room in which they are located and that are intended to be installed directly under a floor covering that is itself intended  to  be removable;
their rated voltage being not more than 250 V for single-phase installations and 480 V for other installations.
                                                                     The contents of the corrigendum of February 2008 have been included
in this copy.