AS NZS 60335.2.96:2020 pdf free.Household and similar electrical appliances- Safety Part 2.96: Particular requirements for flexible sheet heating elements for room heating.
7.12.101 The instructions for applications in floors of concrete or similar material or under tiles shall state that
a) a grid is to be installed above the heating unit. The grid is to
— be protected against corrosion but not electrically insulated;
— be electrically and mechanically equivalent to a steel grid having a mesh not more than
50 mm x 50 mm and a wire diameter of 1 mm, unless the grid covers
• class II heating units;
• heating units installed with additional electrical insulation;
— fully cover the heating unit including the fixing areas. It may cover several heating units:
— be connected to earth;
— be fitted with terminals suitable for the connection of two conductors each having a nominal cross-sectional area of 2,5 mm2
— be checked for electrical continuity during installation.
The grid is not required for
— class Ill heating units;
— class II heating units supplied through an isolating transformer;
— class II heating units that are installed in dry locations (dry locations are areas outside zone 3 as defined in IEC 60364-7-701) and are supplied through a residual current device (RCD);
— heating units installed in dry locations (dry locations are areas outside zone 3 as defined in lEG 60364-7-701) if the basic insulation and additional electrical insulation each withstand the electric strength test of 1 6.3 of reinforced insulation;
— heating units incorporating a metallic shield or braid having a resistance per unit length equivalent to that of 0,5 mm2 copper wire;
b) when the heating units have been positioned, they must be covered with an additional layer of material for mechanical protection. If the heating units are placed on concrete, a similar layer is to be inserted between the heating unit and the concrete. Adjacent layers are to overlap and be fixed to each other. The layer is to extend up each wall to the surface level of the screed. These statements are not required if
— screened insulated heating wires are covered with a sheath complying with 21.103;
— the additional electrical insulation complies with the test of 21.102;
C) when heating units having basic insulation only, other than those supplied at safety extra-low voltage, are provided with additional electrical insulation, this additional insulation is to be placed directly on the heating unit;
d) class II heating units are to be installed at a distance of at least 30 mm from conductive parts of the building, such as water pipes. AS NZS 60335.2.96 pdf download.