What does that require re combustibility?Yes there is - BS EN 61439-3.
Where does it say that?However products to that standard are not considered adequate by BS7671.
And if that is the standard which applies but it is not considered adequate then what about
511.1 Every item of equipment shall comply with the relevant requirements of the applicable British Standard, or Harmonized Standard, appropriate to the intended use of the equipment.
?But if there is no applicable British or Harmonized standard, then how can any comparison as per this be made?I am merely trying to point out that compliance with another country's installation standard would possibly not be sufficient.
Alternatively, if equipment complying with a foreign national standard based on an IEC Standard is to be used, the designer or other person responsible for specifying the installation shall verify that any differences between that standard and the corresponding British Standard or Harmonized Standard will not result in a lesser degree of safety than that afforded by compliance with the British Standard.
How could someone determine if any differences between a non-existing British or Harmonized standard and a foreign one do or do not result in a lesser degree of safety than that afforded by compliance with a standard which does not exist?