Why do flame retardant cable products burn when lit with lighters?

First of all, the definition of flame retardant cable is: flame retardant cable, cable with specified flame retardant properties (including flame retardancy, smoke generation, smoke toxicity). Secondly, flame retardant cable test has strict test conditions, and wind speed, air flow, test product diameter, section, test vessel size, test temperature and other parameters are closely related. Flame retardant cable means that under the specified test conditions, the sample is burned, and after removing the test fire source, the flame spread should be extinguished within a limited range (the standard requirement is to extinguish within a range of 2.5m). The basic characteristics are: in the case of fire may be burned out and can not operate, but can prevent the spread of the fire. Generally speaking, in case of fire, the cable can control the combustion in a local scope, do not spread, keep other equipment, maximize the extension of disaster relief or personnel escape time, avoid causing greater losses; The use of lighters to burn cables on site can only preliminarily determine whether the cables are flame retardant, and cannot be used as a basis for judging the flame retardant ability. So flame-retardant cables are not non-combustible cables.