This International Standard applies to residual current monitors (RCMs) having rated voltage not exceeding 440 V a.c. and rated current 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, and may be used in conjunction with protective devices. RCMs detect residual alternating currents and residual pulsating direct current whether suddenly applied or slowly rising. RCM's having internal batteries are not covered by this standard. This standar