Murray 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 Murray 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. Murray strongly recommends against the use of "used" breakers. The installation of used breakers in a Murray panel will void the warranty on the panel. Murray does not sell used breakers and has not approved any 3rd party sellers to do so.
From the Manufacturer
Murray plug in circuit breakers are intended for use in Murray load centers or meter combinations. The double pole Murray breakers may be used in 1 or 3-phase load centers and are 240V rated. To ensure the warranty on a Murray panel is not voided, the use of Murray breakers is required.