This European Standard specifies the minimum level of resistibility of equipment having telecommunications port(s) to overvoltages and overcurrents. This European Standard covers telecommunications equipment installed at customer premises as shown in Figure 1. Overvoltages or overcurrents covered by this European Standard are surges due to direct or indirect lightning on the telecommunication line plant. Overvoltages or overcurrent not covered by this European Standard are - short-term induction of alternating voltages from electric power systems (including electrified railway), - earth potential rise due to power faults or load switching, - direct contacts between telecommunication lines and low voltage power lines. This European Standard is intended for use by network (public/private) operators and the equipment manufacturers. This European Standard applies to equipment having telecommunications port(s) connected to external conductors, i.e. conductor located outside the customer's building. The tests are type tests and, although they are applicable to a complete system, it is recognised that they may be applied to individual items of equipment during development and design work.