Siemens Low Voltage Residential Circuit Breakers Small Circuit Breakers Thermomagnetic Circuit Breakers - Duplex, Triplex, Quadruplex are circuits, protective load center networks, feeders and small circuit breakers. Siemens offers a wide array of thermal-magnetic circuit breakers that are the key element for overload and short-circuit protection of your home's electrical system. To provide additional protection Siemens offers circuit breakers to protect against severe electrical shock or electrocution, mitigate the risk of electrical fires and protect against damaging surges and Voltage spikes. Circuit breakers are intended for switching and protection of your home's wiring from high temperatures caused by excess current higher than the rating of the wire. While thermal-magnetic circuit breakers are the key element for overload and short-circuit protection of your electrical system, there are potentially dangerous conditions that do not involve over current. Siemens strongly recommends against the use of "used" breakers. Siemens does not sell used breakers and has not approved any 3rd party sellers to do so.