What is the F-symbol and where does it stand for. The F-symbol was at one time introduced to indicate a luminaire that can be used on normally flammable surfaces. These surfaces are for example would ceilings. At that time you could have a product with or without the symbol. When haven a product without the symbol it was only suitable for mounting on nonflammable surfaces.
In the years a lot has changed and luminaries are more and more build in and we have also started to use insulation materials that are blocking the heat from the luminaries as well. Luminaires can be build in ceilings where the insulation material is lying over the luminaire. Result was that the F-symbol was no longer sufficient and a different method was needed for indicating how the luminaire could be used/fixed.
In the past a luminaire suitable for fixing on nonflammable surfaces was not marked. Strange since there is a limitation for these products. Clearly when luminaires fitted on a flammable surfaces like for example a wooden ceiling a problems could occur.
In a later stadium there was a symbol made for luminaries that where not suitable for mounting on normally flammable surfaces. That was a F-symbol with a cross through it. This did not make it much clearer since the symbol did not really indicate clearly what it meant.
The F-symbol was replaced. There are new symbols introduced that replace this marking and this marking is now more logical. How do I mean that?
In the new situation the symbol on luminaries that can be fitted on normally flammable surfaces is no longer marked. Logical since it is safe to fix them to basically all surfaces. The luminaries that are not suitable for these surfaces must be marked with a symbol showing a luminaire and flames on the surface. You can debate the clarity of the symbol but principle is clear and more logical.
One thing must be clear as well. Luminaire can be fitted on normally flammable and nonflammable surfaces but never on easily flammable surfaces.
Also the F-symbol for products that are build-in was changed. The principles are the same as for surface mounted luminaire however in this case also insulation materials have been taken into account.
The original F-symbol was now completely abandoned. So luminaries with F-symbol should no longer be found on the market place in the present time. In below table you can see the symbols with the declarations of what they exactly mean.