[1] Class A fires consist of ordinary combustibles such as wood, paper, fabric, and most kinds of trash.
A solid stream of water should never be used to extinguish this type because it can cause the fuel to scatter, spreading the flames.
Certain metals catch fire in contact with air or water (for example, sodium), which exacerbates this risk.
In consequence, significant heat energy is required to ignite a contiguous mass of combustible metal.
Water and other common firefighting agents can exacerbate metal fires and make them worse.
This sort of fire may be caused by short-circuiting machinery or overloaded electrical cables.
Once electricity is shut off to the equipment involved, it will generally become an ordinary combustible fire.
Some special extinguishers designed for this use smother the fire by turning the oil into a foam.
As with Class B fires, a solid stream of water should never be used to extinguish this type because it can cause the fuel to scatter, spreading the flames.
Commercial kitchens may also have a fire suppression system built into the exhaust hood to release an extinguishing agent onto the stove top, releasing automatically with a fusible link or manually using a pull station.
Preferably a lid or a similar solid item should be used to seal the burning container off from the surrounding atmosphere.