EN 50264-1 specifies the general requirements applicable to the cables given in all other parts of EN 50264. It includes the detailed requirements for the insulating and sheathing materials and other components called up in the separate parts. In particular EN 50264-1 specifies those requirements relating to fire safety. Based on proven experience and reliability over many years these cables are rated for occasional thermal stresses causing ageing equivalent to continuous operational life at a conductor temperature of 90 °C. NOTE This rating is based upon the polymers defined in 3.1 and 3.2. Before these polymers had gained widespread acceptance in the cable industry, ageing performance had been assessed via long-term thermal endurance testing and had been extrapolated to 20 000 h using techniques equivalent to those in EN 60216 (series). Subsequent experience in service has demonstrated that the predicted performance levels were correct. Where extrapolated data is used to predict lifetime in service it should be confirmed with the cable manufacturer, and should be on the basis of a failure mode appropriate to the type of material or cable. The maximum conductor temperature for short circuit conditions is 200 °C based on a duration of 5 s. This Part 1 should be read in conjunction with the other parts of EN 50264.