IEC 61557-1:2019 RLV contains both the official IEC International Standard and its Redline version. The Redline version is not an official document, it is available in English only and provides you with a quick and easy way to compare all the changes between the official IEC Standard and its previous edition.

IEC 61557-1:2019 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 can specify additional requirements or deviations. This document does not cover functional safety or cybersecurity. IEC 61557-1:2019 cancels and replaces the second edition published in 2007. This edition constitutes a technical revision. This third edition includes the following significant technical changes with respect to the previous edition:
a) terms aligned with IEC 60050;
b) measurement of uncertainty revised according to the equations in 4.2 of ISO/IEC Guide 98-3:2008 (GUM);
c) updated references for safety and EMC requirements;
d) updated references for marking and operating instructions;
e) updated references for testing safety and EMC;
f) Annex A contains an explanation of GUM;
g) Annex B addresses environmental aspects.