This Guide provides an overview of protection availability provided by 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.