This document applies to railway signalling and telecommunication trackside equipment. This document does not cover signalling and telecommunication equipment mounted in vehicles; these are covered by EN 50155:2021. This document covers the type testing phases of the equipment for signal and telecommunication (S&T) system (including power supply systems belonging to S&T), in order to ensure compliance with specified requirements already defined in the customer specifications or by the involved parties. In particular this document intends to define test requirements with related performance / acceptance criteria, considering only the environmental conditions stated by the EN 50125 3:2003, and considering the severities of the environmental parameters herein defined. Safety considerations are not covered by this document.