The circular panels penetrate the ceiling but I can't find any mention of them being "fire rated", are there any that are? If not, what do people do? It seems that some (most?) of the rectangular and square panels can sit under an unbroken ceiling, which would be wise because when one fails it probably won't be easy to find a replacement to fit into a girt big hole. What are people's experiences with these panels? Prices seem to vary from tens of pounds to hundreds for similar light output. I'm loath to fork out for two or three at £150, or so, each. Are there any makes/models to look for or avoid?