DS/EN 61557-8:2015

Electrical safety in low voltage distribution systems up to 1 000 v a.c. And 1 500 v d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 8: insulation monitoring devices for IT systems

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Harmonized under:
  • Directive 2014/35/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of electrical equipment designed for use within certain voltage limits Text with EEA relevance

Harmonized standards:


IEC 61557-8:2014 specifies the requirements for insulation monitoring devices (IMD) which permanently monitor the insulation resistance RF to earth of unearthed a.c. IT systems, of a.c. IT systems with galvanically connected d.c. circuits having nominal voltages up to 1 000 V a.c., as well as of unearthed d.c. IT systems with voltages up to 1 500 V d.c. independent from the method of measuring. IT systems are described in IEC 60364-4-41 amongst other literature. Additional data for the selection of devices in other standards should be noted. IMDs according to this part of IEC 61557 can also be used for de-energized TT, TN and IT systems or appliances. This third edition cancels and replaces the second edition published in 2007. This edition constitutes a technical revision which includes the following significant technical changes with respect to the previous edition:

- terms and definitions have been complemented;

- abbreviations are listed and explained;

- requirements have been revised;

- mandatory and optional functions and their terminology have been adapted from IEC 61557-15;

- mechanical requirements have been added;

- information on operating instructions has been added;

- type tests and routine tests have been complemented;

- an Annex C: 'Insulation monitoring devices for photovoltaic systems (PV-IMD)' has been added; and

- an Annex D: 'Insulation monitoring function of a photovoltaic inverter (PV-IMF) or in a charge controller' has been added.

Number of pages: 53

Published: 2016-04-07

Date of approval: 2015-02-17

International relationships : EN 61557-8:2015 IDT IEC 61557-8:2014 IDT

ICS: 29.240.01 - Power transmission and distribution networks in general 17.220.20 - Measurement of electrical and magnetic quantities 29.080.01 - Electrical insulation in general

Item number: M278057



  • CLC/TC 85X
  • IEC/TC 85

Danish committee



  • DS-håndbog 193:2021
    Guidance on the design of electrical installations. With special focus on fault protection in TT, TN and IT installations