FuseBox 40A Single Pole 1 Module B Curve 6kA 30mA Type A RCBOFuseBox RCBO 40amp Type A B Curve RTA064030B Overview The RTA064030B RCBO is designed for use in FuseBox consumer units. These single pole Type A RCBOs respond to both AC and pulsating DC residual currents and protect against both overcurrents due to overload and fault and residual current earth leakage. In either event, the RCBO interrupts the electrical supply to the circuit thus preventing damage to the installation and devices and electric shock