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.
Here two receptacles in one box are wired using the device terminals. With this arrangement, if receptacle #1 fails, receptacle #2 may also fail if failure is due to physical damage. However, if the copper tab conductors between the terminals remain intact, even if #1 stops functioning, receptacle #2 will probably still work.
In this arrangement a light fixture and exhaust fan are wired to the same source. The light is controlled with a single-pole switch and the fan controlled with a timer as in the previous drawing. The hot source is spliced to each controlling device and the output of the controllers are connected as in the previous diagrams on this page.
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.