For any product to qualify for use in a rated ceiling, it has to pass a fire test...it is actually installed in a ceiling, and the assebmly is exposed to a defined fire; the results must pass the same criteria as the ceiling passed without the product.
As you might guess, it is essential that the product be installed as specified by the manufacturer, and not altered. The limitations of the rating agency need also be obeyed.
The fire tests are quite realistic; a very large piece of ceiling is constructed (appx 20 ft. sq), and is subjected to an enormous, controlled natural gas fire for a specific time. Temperatures are monitored on the "unexposed" face; for it will not do much good if the outside itself gets hot enough to light a new fire! Nor will it help if the structure is weakened to the point of collapse.
