How does residual current monitoring work?

RCM - RCD: The difference

RCMs (Residual Current Monitors) monitor residual currents in electrical installations, indicate the present value and signal when the response values are exceeded.

The devices are designed for signalling and/or switching. They comply with DIN EN 62020 (VDE 0663) “Electrical accessories – Residual current monitors for household and similar use (RCMs) (IEC 62020)”.

In contrast to RCMs, RCDs (residual current protective devices) are designed to provide protection in electrical installations in accordance with the standard IEC 60364, e.g. in bathrooms. RCDs always cause a shutdown.