What can dry powder fire extinguishers not be used?

ABC Powder fire extinguishers cannot be used on Class D and Class F fires. However they are a very versatile extinguisher that can be used on Class A (carbonaceous items), Class B (flammable liquids), Class C (flammable gases) and Electrical fires. These fire extinguishers should also not be used in non-ventilated areas due to the powder being harmful if ingested.