According to the standard BS EN 3, fire extinguishers in the UK are red RAL 3000, this is their colour code according to the RAL chart, there is also a band or circle of colour covering between 5-10% of the surface area of the extinguisher indicating the contents. However before 1997, the entire body of the fire extinguisher was colour coded according to the type of extinguishing agent. There are six fire classes which are recognised in the UK. Class A fires involve organic solids such as paper or wood. Class B fires involve flammable or combustible liquids. Petrol, grease and oil fires are included in this class. Class C fires involve flammable gases. Class D fires involve combustible metals. Class E fires involve electrical appliances. Cass F fires involve cooking fat and oil. EN3 does not recognise a separate electrical class-however there is an additional feature requiring special testing (35 kV dielectric test per EN 3-7:2004). A powder or CO2 extinguisher will bear an electrical pictogramme as standard signifying that it can be used on live electrical fires (given the symbol E in the table). If a water based extinguisher has passed the 35kV test it will also bear the same electrical pictogramme-however, any water based extinguisher is only recommended for inadvertent use on electrical fires.