In the hands of a properly trained person, a fire extinguisher can save lives and protect property. Extinguishers are designed to extinguish or contain small fires. Even against small fires they have limits. The extinguisher must be of the proper class. Must be large enough.
Most extinguishers discharge in seconds.
The extinguisher must be operable and within reach. The operator must know how to use the extinguisher. The extinguisher you use must be matched to the type of material that's burning. Energized electrical equipment, including wiring, fuse boxes, circuit breakers, machinery, and appliances. You must match the correct class of extinguisher with the type of material burning.