Siemens 20-amp GFCI Circuit Breaker Model #QF120AP Siemens GFCI circuit breakers are UL Listed and CSA Certified as Class A devices. These circuit breakers offer the new Self-Test and Lockout 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 homeowner from resetting the device, reducing the possibility of the homeowner incorrectly assuming that the device was tripped to prevent a ground fault. Device intended for personnel protection from Ground Faults LED trip indicators to help identify fault conditions Autonomously and continuously tests itself for device malfunction Suitable for a variety of construction applications including spas, hot tubs, kitchens, bathrooms, etc Self-test and lockout feature enables the GFCI circuit breaker to automatically and continuously test itself to ensure that it is working properly as required by UL 945 Resists false tripping (shielded to prevent RF interference) Class A (5 mA) ground fault protection White line neutral (pigtail) must be connected to the panel neutral for the device to function #14 - #8 AWG copper, #12 - #8 AWG aluminum wire range