The Carriage of Explosives by Road Regulations 1996

2.—(1) The fire extinguisher referred to in paragraph 1(a) need not be suitable for fighting a fire in the engine if the vehicle is equipped with a fixed fire extinguisher, suitable for fighting a fire in the engine, which either works automatically or is easily brought into action.

(2) Where the vehicle is a motor vehicle with a permissible maximum weight of less than 3.5 tonnes, the fire extinguisher referred to in paragraph 1(b) may be replaced by a fire extinguisher with a minimum capacity of 2 kilograms of dry powder or other suitable extinguishant with an equivalent test fire rating of at least 5A and 34B as defined in British Standard BSEN 3-1: 1996.