International Electrotechnical Commission

Electrical accessories   Residual current monitors for household and similar uses (RCMs) - Edition 1.1; Consolidated Reprint
 N 62020

Annotation

This International Standard applies to residual current monitors having rated voltages not exceeding 440 V a.c. and rated currents not exceeding 125 A for household and similar purposes.

These devices are intended to monitor the residual current of the installation and to give a warning if the residual current between a live part and an exposed conductive part or earth exceeds a predetermined level.

RCMs covered by this standard are not intended to be used as protective devices.

RCMs detect residual alternating currents and residual pulsating direct currents whether suddenly applied or slowly rising

This standard applies to monitors performing simultaneously the functions of detection of the residual current, of comparison of the value of this current with the residual operating current of the device and of providing the prescribed warning signal(s) when the residual current exceeds this value.

RCMs having internal batteries are not covered by this standard.

The requirements of this standard apply for normal environmental conditions. Additional requirements may be necessary for RCMs used in locations having severe environmental conditions.

This standard does not cover Insulation Monitoring Devices (IMDs) which are covered by the scope of IEC 61557-8.

NOTE An RCM is distinguished from an IMD in that it is passive in its monitoring function and only responds to an unbalanced fault current in the installation being monitored. An IMD is active in its monitoring and measuring functions in that it can measure the balanced and unbalanced insulation resistance or impedance in the installation