Murray AFCI plug in circuit breakers are intended for use in Murray load centers or meter combinations. The single pole Murray breakers may be used in single or 3-phase load centers and are 120V rated. To ensure the warranty on a Murray panel is not voided, the use of Murray breakers is required. The branch feeder type AFCI is for use in areas enforcing the 2002 and 2005 National Electric Code. Check with your local electrical inspector to confirm.