Hjælpeudstyr, der drives af motoren eller selvstændigt, for eksempel rudeviskere, varmeanlæg, kraftudtag, osv. skal være frakoblet under målingerne, hvis det kan indvirke på målingen af støjniveauet; dele, som normalt virker sammen med motoren, for eksempel motorens kølerventilator, skal være i gang under målingerne.
if it is liable to affect the noise level, extra equipment powered by the engine or self-powered such as windscreen wipers, warm air fan or power take-off, for example, may not be in operation when measurements are being made; parts which normally operate at the same time as the engine, such as the engine cooling fan, for example, must be in operation when measurements are being made;