Fires are classified as three types:
CLASS A = an "ordinary" fire that involves the burning of wood, paper, or textile products. A wetting/cooling type of extinguishing agent (water) should be used.
CLASS B = a fire that contains oil, grease, paint, varnish, or other chemicals. A smothering agent (foam) is required for extinguishing this type of fire.
CLASS C = an electrical fire. A nonconducting agent, such as carbon dioxide ( CO2 ), is required to extinguish this type of fire.
Note: since CO2 is monconductive it is the safest to use in terms of electrical safety. Also offers the likelihood of damaging equipment. However, it is dangerous to human life. When it replaces oxygen in the air to the extent that combustion cannot be sustained, respiration also cannot be sustained. Exposure of a person to an atmosphere of high concentration of CO2 will cause suffocation.