Fire extinguishers come in various classes and sizes. The class of the extinguisher informs the user of what kind of fire the extinguisher will be effective against. The different classes are:
Class A - Ordinary combustibles (wood, paper, plastic, and cloth)
Class B - Flammable liquids (grease and oil)
Class C - Electrical equipment (TVs, VCRs, power tools, and kitchen appliances)
Class D - Combustible metals (magnesium)
It is very important to know what is on fire and use the proper extinguisher. Using the extinguisher on the wrong class of fire can make the fire worse or be fatal to the user (i.e., using an extinguisher on electrical devices that is not Class C-rated or using an extinguisher on a cooking grease fire that is not Class B-rated). A safe alternative is to use a multi-use Class ABC-rated extinguisher.
Size Does Makes a Difference
The size of the extinguisher is given a numerical rating that informs the non-expert user of the approximate square feet of fire area it may extinguish. The minimum rated extinguisher for home use is a 1A:10BC extinguisher. However, the recommended size is 2A:10BC extinguisher, which is the minimum size for commercial use.