This Part 1 of EN 50382 specifies the general requirements applicable to the cables given in EN 50382-2. It includes the detailed requirements for the insulating and sheathing materials and other components called up in EN 50382-2. In particular EN 50382-1 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 either 120 °C or 150 °C.NOTE This rating is based upon the polymer defined in 3.1. Before this polymer 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. 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 based on a failure mode appropriate to the type of material or cable. The maximum temperature for short circuit conditions for silicone rubber is 350 °C based on a duration of 5 s. Although both of the insulating and one of the sheathing compounds specified in this standard are thermally capable of operating at 150 °C, where tinned conductors are used the maximum operating temperature is limited to 120 °C and for the same technical reason the maximum short circuit temperature, for tinned copper conductors, is limited to 250 °C. The choice of sheath may also limit the operating temperature to 120 °C.This Part 1 should be used in conjunction with EN 50382-2.