Final answer:
Luminaires in dropped ceilings require labels such as those from Underwriters Laboratories (UL) for safety and performance standards. To compare the brightness of light bulbs, look for the lumen rating on the labels.
Step-by-step explanation:
Luminaires installed in a dropped ceiling are required to have specific labeling indicating that they are suitable for such use, often including safety and performance standards. For example, a label from the Underwriters Laboratories (UL) is common, which signifies that the luminaire complies with industry standards for installation in a dropped ceiling environment. When it comes to comparing the brightness of light bulbs, you should refer to the labels for their rating in terms of lumens, which directly measures the amount of light output.