This European Standard specifies the general service conditions and requirements for all electric equipment installed in power circuits, auxiliary circuits and control circuits etc. on rolling stock. NOTE 1 Certain of these rules may, after agreement between user and manufacturer, be used for electrical equipment installed on other vehicles such as mine locomotives, trolley-buses etc. The purpose of this standard is to harmonize as far as practicable all rules and requirements of a general nature applicable to electric equipment for rolling stock. This is in order to obtain uniformity of requirements and tests throughout the corresponding range of equipment to avoid the need for testing to different standards. This general standard is to be read in conjunction with the relevant equipment standard hereafter referred to as "the relevant product standard" or "product standard". NOTE 2 In the event of there being a difference in requirements between the basic standard and a product standard produced by the Technical Committee TC 9X, the product standard requirements are to take precedence. For a general rule to apply to a specific product standard, it is to be explicitly referred to in the latter, by quoting the relevant clauses of this standard e.g. see 7.7 of EN 60077-1. A specific product standard may not require, and hence may omit, a general rule (as being not applicable), or it may add to it (if deemed inadequate in the particular case), but it may not deviate from it, unless there is a substantial technical justification.