Siemens 50 amps Ground Fault 2-Pole Circuit BreakerSiemens GFCI circuit breakers are UL Listed and CSA Certified as Class A devices. These circuit breakers offer the new Self test and lock out feature as required by UL 943, enabling the GFCI to automatically and continuously test itself to ensure that it is working properly. If it is detected that the device has been compromised, the device trips itself and locks out the home owner from resetting the device, reducing the possibility of the homeowner