IEC 60871-1:2014 is applicable to both capacitor units and capacitor banks intended to be used, particularly, for power-factor correction of a.c. power systems having a rated voltage above 1 000 V and frequencies of 15 Hz to 60 Hz. This part of IEC 60871 also applies to capacitors intended for use in power filter circuits. The object of this part of IEC 60871 is as follows: - to formulate uniform rules regarding the performance and rating of units and banks, and the testing of units; to formulate specific safety rules; - to provide a guide for installation and operation. This fourth edition cancels and replaces the third edition published in 2005. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: - the overvoltage cycling test has been moved to this standard from the IEC 60871-2; - the ranges of the standardized values of the highest voltage for equipment have been modified; - for installations installed on altitudes above 1 000 m a correction factor to all insulation requirements has been introduced; - new standard insulation tables have been defined. Keywords: capacitor units and capacitor banks, power filter circuits