The Road Vehicles (Construction and Use) Regulations 1986

1.  The power of an engine, which is to be shown only in the case of a compression ignition engine on the plate in respect of item 3 in Part I of this Schedule, shall be the amount in kilowatts equivalent to the installed power output shown in a type test certificate issued—

(a) by a person authorised by the Secretary of State for the type of engine to which the engine conforms; and

(b) in accordance with either—

(i) the provisions relating to the installed brake power output specified in the British Standard Specification for the Performance of Diesel Engines for Road Vehicles published on 19th May 1971 under the number BS AU 141a: 1971;

(ii) the provisions relating to the net power specified in Community Directive 80/1269 but after allowance has been made for the power absorbed by such equipment, at its minimum power setting, driven by the engine of the vehicle as is fitted for the operation of the vehicle (other than its propulsion) such power being measured at the speed corresponding to the engine speed at which maximum engine power is developed; or

(iii) the provisions of Annex 10 of ECE Regulation 24.02 as further amended with effect from 15th February 1984 relating to the method of measuring internal combustion engine net power, but after allowance has been made for the power absorbed by any disconnectable or progressive cooling fan, at its maximum setting, and by any other such equipment, at its minimum power setting, driven by the engine of the vehicle as is fitted for the operation of the vehicle (other than its propulsion), such power being measured at the speed corresponding to the engine speed at which maximum engine power is developed.