Here GFCI’s are wired to a double-pole circuit breaker with the source split to provide 120 volts to two sets of receptacles. The neutral from the source is shared by both sets. Single-location protection is provided by each receptacle.
This diagram illustrates the wiring for a Cooper gfci/switch combo device wired to protect a garbage disposal. With this arrangement a receptacle, switch and disposal are protected with the ground fault breaker built into the device.
In this diagram, two receptacle outlets are wired in the same box with a separate 120 volt source feeding each. Three-wire cable runs into the box. The black and red wires are hot and each is connected to one of the receptacles. The white, neutral wire is splice to each outlet so they share the return path. This is appropriate for standard duplex receptacles, but should not be used for GFCI receptacles. GFCI’s must have dedicated neutral connections to work properly.
This diagram is similar to the one above, but with the electrical source originating at the fixture. Three-wire cable runs from there to the controllers. The neutral wire from the source is spliced directly to the white wire on the fan/light. The hot source wire is spliced to the white on the 3-wire cable and then spliced to the input wires on both controllers at the other end.