This European Standard specifies the environmental conditions encountered within Europe. It can also be applied elsewhere by agreement between the supplier and the customer. The scope of this European Standard covers the design and the use of equipment and any portable equipment for signalling and telecommunications systems (including test, measure, monitoring equipment, etc.). The portable equipment must comply with the sections of this European Standard relevant to their use. This European Standard does not specify the test requirements for equipment. In particular the standard intends to define: - interface conditions between the equipment and its environment, - parameters to be used by designers when calculating R.A.M.S. and life time with respect to environmental condition effects. In this respect it gives general guidance in order to allow consistent assessments of contract documentation for European projects. The defined environmental conditions are considered as normal in service. Microclimates surrounding components may need special requirements to be defined by the product standard. The effects of any signalling and telecommunications equipment (in either or failure mode of operation) on the overall signalling system safety are not within the scope of this European Standard. This European Standard does not provide the designer with information to enable him to determine the safety risk associated with environmental conditions.