- Standard thermal-magnetic QO® and Homeline™ 15 and 20 A circuit breakers are listed to UL489 and provide overload and short circuit protection for conductors. The QO® and Homeline™ thermal-magnetic circuit breakers are for general use in protecting branch circuit in residential and commercial applications. Use QO® and Homeline™ 15 and 20 A arc fault circuit interrupter circuit breakers that have been listed to UL1699 in order to provide arc fault circuit protection for the entire branch circuit in accordance with the installation requirements in National Electrical Code section 210.12. Thermal-magnetic circuit breakers are not designed, listed or intended to provide protection against low level hazardous arcing conditions in branch circuit wiring.