A full scale fire test is used since long in Sweden to classify surface products. The test method was developed together with the method NT FIRE 004 and is now revised and brought up to date. The test conditions are, however, not changed. All equipment used is thoroughly described. The preparation of the test sample and the test procedure is clearly specified. A system to measure the light obscuration of the smoke is tried out. Some tests are done to verify the ability to measure different amounts of smoke with the system. A photocell system is designed and described in the annex of the method description. The use of the system is not mandatory for performing a test. The test method description is edited according to the directions of ISO GUIDE for the presentation of International Standards and Technical Reports and NORDTEST Guide for the Presentation of NORDTEST Methods.