In many applications, electrical and electronic equipment must operate reliably for many years under difficult environmental conditions. This also includes lighting systems for vehicles, trailers and agricultural machinery. Therefore, the penetration of foreign bodies and dust as well as the mechanical stress must be prevented for a reliable function and safe use.
The test methods for the IP protection classes attempt to replicate common error possibilities. For example, IP 2X is to be tested using a simulated finger, IP 3X provides protection against access with tools, IP 4X protection against access by wire. In practice, as is also the case in EU directives. For vehicles and the following standards, appropriate IP test probe sets are used to ensure that access to certain parts is not possible.