This International Standard applies to residual current operated circuit-breakers with integral overcurrent protection functionally independent of, or functionally dependent on, line voltage for household and similar uses (hereafter referred to as RCBOs), for rated voltages not. This International Standard applies to residual current operated circuit-breakers with integral overcurrent protection functionally independent of, or functionally dependent on, line voltage for household and similar uses (hereafter referred to as RCBOs), for rated voltages not. The residual current device (RCD) or residual current circuit breaker (RCCB) enables the rapid disconnection of electricity, thereby avoiding prolonged and potentially serious shocks. An RCD device complete with overcurrent protection is called an RCBO, or residual current circuit breaker with. It can swiftly disconnect the circuit when a fault current happens and prevent wiring damage. In this article, we explain what an RCBO is and how it works. Understanding the iec standard for rccb is critical for engineers, electricians, and facility managers who want to ensure safety. [The basis of this article was first published in Wiring Matters in issue 15, Summer 2005 and reflected the requirements of the then current BS 7671:2001(2004). The Regulations have since been revised and amended a number of times so, due to many requests, a revisit was seen as necessary. ] The IET. s intended to protect people against electric shocks.