This European Standard specifies requirements, test methods and performance criteria for line smoke detectors utilising the attenuation and/or changes in attenuation of an optical beam, for use in fire detection systems installed in buildings. This European Standard does not cover: ¾ Line smoke detectors designed to operate with separations between opposed components of less than 1 m; ¾ Line smoke detectors whose optical path length is defined or adjusted by an integral mechanical connection; Line smoke detectors with special characteristics, which cannot be assessed by the test methods in this European Standard.