What class of fire suppression is determined by quality rather than rating?

The correct class of fire suppression that is determined by quality rather than rating is Class C. Class C fires involve energized electrical equipment, such as motors, generators, transformers, and other devices that conduct electricity. The suppression of these types of fires requires specific extinguishing agents that do not conduct electricity, ensuring that the electrical hazard is not exacerbated during firefighting efforts.

In the context of quality versus rating, Class C fire extinguishers are evaluated based on their effectiveness in handling electrical fires rather than a numerical rating system like in Classes A and B, which may assess performance against specific types of combustibles (like common combustibles for Class A or flammable liquids for Class B). The actual extinguishing agent used is dictated more by its secure application and safety around electrical components than by a standard rating.

As such, while Classes A and B utilize ratings based on capable extinguishment scenarios—A for ordinary combustibles and B for flammable liquids—Class C extinguishers focus on qualitative aspects, such as being non-conductive, which directly informs the choice of extinguishing agent in electrical fire situations.