EN 50021:1999

Electrical apparatus for potentially explosive atmospheres - Type of protection "n"

This European Standard specifies requirements for the construction , testing and marking for Group II electrical apparatus with type of protection 'n', intended for use only in areas where explosive atmospheres of gas, vapour and mist are unlikely to occur or if they do occur, are likely to do so infrequently or for a short period only. This standard is applicable to non-sparking electrical apparatus and also to apparatus with parts or circuits producing arcs or sparks or having hot surfaces which, if not protected in one of the ways specified in this standard, could be capable of igniting a surrounding explosive atmosphere. A non-incendive part is limited in use to the particular circuit for which it has been shown to be non-ignition capable and, therefore, cannot be separately assessed as complying with this standard. This standard is applicable to electrical equipment and components of Group II, Category 3G. Such equipment is designed to be capable of functioning in conformity with the operating parameters established by the manufacturer and ensuring a normal level of protection. Equipment in this category ensures the requisite level of protection during normal operation. NOTE 1: In this standard the word 'apparatus' has the same meaning as the word 'equipment' used in the Directive. Compliance with this European Standard does not imply any removal of, or lowering of, the requirements of any other European Standard with which the electrical apparatus complies. This standard supplements, and may supersede, the requirements for apparatus for normal industrial applications. NOTE 2: The application of this standard may require the exercise of engineering judgement because of the wide range of apparatus and technologies covered. If apparatus is to be certified the relevant requirements may need to be agreed between the manufacturer and the testing station