This technical report provides an overview of protection availability provided by residual current-operated protective devices (RCDs) complying with IEC standards for household and similar uses. It highlights the main parameters influencing protection reliability and provides information on how to install and operate RCDs in relationship to their environmental conditions after installation. This guide gives general information concerning availability of the protection within the fixed installation and how to keep a high level of availability of protection during use (installation and maintenance). It has been drafted for the benefit of IEC technical committees, installers, inspectors and users. NOTE 1 The term RCD is a generic term applied to a family of products which open automatically in response to a residual current at or exceeding the RCD’s rated residual operating current, I Δn. This generic term is often applied to the following. RCCB - Residual Current Circuit Breaker without overcurrent protection RCBO - Residual Current Breaker with Overcurrent protection SRCD - Socket outlet Residual Current Device PRCD - Portable Residual Current Device A RCCB differs from a RCBO in that the RCBO will additionally respond to overcurrent conditions whereas the RCCB will not respond to such conditions. NOTE 2 PRCDs are not considered to be part of the fixed installation, and are not covered by this guide.