EN 50306-3 specifies requirements for, and constructions and dimensions of, multicore cables, rated 300 V to earth, of the following type:Screened (0,5 mm2 to 2,5 mm2, number of cores from 1 to 4)All cables have stranded tinned copper conductors, and thin wall thickness, halogen-free, insulation and sheath. They are for use in railway rolling stock as fixed wiring, or wiring where limited flexing in operation is encountered. The requirements provide for a continuous operational life at temperatures of 90 °C or 105 °C dependent upon the sheath system type.NOTE 1 For cables with type S2 sheath a temperature of 105 °C is only allowed when specifically tested for the higher rating (i.e. by long-term thermal endurance testing to demonstrate a lifetime of at least 20 000 h at 125 °C).The maximum temperature for short-circuit conditions is 160 °C based on a duration of 5 s.Under fire conditions the cables exhibit special performance characteristics in respect of maximum permissible flame propagation (flame spread) and maximum permissible emission of smoke and toxic gases. These requirements are specified to permit the cables to satisfy Hazard Levels 2, 3 or 4 of EN 45545-1 1).NOTE 2 Requirements for the emission of smoke and gases are not specified for cables used for Hazard Level 1 of EN 45545-1.NOTE 3 EN 45545-1 is still under development and should be consulted.EN 50306-3 should be used in conjunction with EN 50306-1, General Requirements, and EN 50306 2, Single core cables.