DIN EN IEC 61557-1:2025-09

IEC 60364-6 specifies uniform prerequisites for the initial testing of low-voltage installations in TN, TT, or IT systems for continuous monitoring and testing of these installations following modifications. In addition to general guidelines for conducting the tests IEC 60364-6 contains several requirements that shall be verified through measurements. Only in a few cases does IEC 60364-6 provide specific details with regard to the characteristics of the measuring equipment to be used; for example, when measuring insulation resistance. The sample measurement circuits shown in IEC 60364-6, to which the text of this document refers, are generally unsuitable for practical use. Tests are performed in installations with hazardous voltages, where an accident may very easily occur due to careless handling or a defect in the installation. Thus the tester is dependent on measuring equipment that not only simplifies the measurements, but also ensures safe measurement. Application of the standard safety regulations for electrical and electronic measuring equipment (IEC 61010-1) therefore does not suffice with regard to measuring equipment used to test protective measures. When taking measurements in installations hazards may arise not only for the tester but also, depending on the method of measurement, for non-participants. Furthermore, reliable and comparable measurement results using measuring equipment from different manufacturers are an important prerequisite for objective assessment of an installation; for example, during delivery, during repeat tests, for continuous insulation monitoring, or in cases of warranty. The aim of the IEC 61557 series of international standards is to define common principles for measurement and monitoring equipment used to test electrical safety and measurement performance in distribution systems with rated voltages up to 1 000 V AC and 1 500 V DC that correspond to the aforementioned aspects. This is achieved through a set of common requirements in IEC 61557-1 (other parts of the IEC 61557 series may contain additional requirements or deviations): - immunity to external voltages; - protection class II (except for insulation monitoring devices and equipment for insulation fault detection); - specifications and precautions against hazards caused by dangerous contact voltages on the DUT; - specifications for assessing connection configurations or circuit faults in the tested installation; - special mechanical requirements; - measurement procedures; - measured quantities; - specification of the maximum operational uncertainty in measurement; - specifications for testing variations and calculating the operational uncertainty in measurement; - consideration of the uncertainty of the measuring equipment at the limit values specified by the installation regulations; - specification of the types of type and unit tests and their required test conditions. By way of departure from common practice, terms that are specified more than once in other parts of the series of standards are listed in IEC 61557-1:2019, Clause 3. Only terms and definitions that specifically apply to the respective part of IEC 61557 are listed there in Clause 3. This document does not cover functional safety or cybersecurity. This part of IEC 61557 specifies the general requirements applicable to measuring and monitoring equipment for testing the electrical safety in low-voltage distribution systems with nominal voltages up to 1 000 V AC and 1 500 V DC. When measuring equipment or measuring installations involve measurement tasks of various measuring equipment covered by this series of standards, then the part of this series relevant to each of the measurement tasks is applicable. Other parts of IEC 61557 may specify additional requirements or deviations.