Murray GFCI plug in circuit breakers are intended for use in Murray load centers or meter combinations. The single pole Murray breakers may be used in 1 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 GFCI is intended for areas required by code to have ground fault protection, such as bathrooms, kitchens, and outdoor circuits. Check with your local electrical inspector to confirm. The use of a double pole AFCI allows for shared neutral applications in which two circuits will share a common neutral.