IEC 61557-9:2014 specifies the requirements for the insulation fault location system (IFLS) which localizes insulation faults in any part of the system in unearthed IT a.c. systems and unearthed IT a.c. systems with galvanically connected d.c. circuits having nominal voltages up to 1 000 V a.c., as well as in unearthed IT d.c. systems with voltages up to 1 500 V d.c., independent of the measuring principle. IT systems are described in IEC 60364-4-41 amongst other literature. Additional data for a selection of devices in other standards should be noted. This third edition cancels and replaces the second edition published in 2009. This edition constitutes a technical revision which includes the following significant technical changes with respect to the previous edition:
- the scope, normative references, terms and definitions have been complemented;
- abbreviations are listed and explained;
- requirements, marking and operating instructions have been revised;
- mandatory and optional functions have been defined and their terminology has been adapted to IEC 61557-15;
- mechanical requirements have been added;
- Clause 6 "Tests" has been revised; and
- new Tables have been added.

This publication is to be read in conjunction with IEC 61557-1:2007. The contents of the corrigenda of May 2016 and of January 2017 have been included in this copy.