Wiring Diagrams for Electrical Receptacle Outlets - Do-it Wiring Diagram for a 20-Amp 120-Volt Duplex Receptacle. A 20 amp, 120v duplex receptacle outlet like this should be installed in a circuit using 12 awg cable and a 20 amp circuit breaker. These receptacles are usually found in kitchen wall outlets where two branch circuits are needed to serve small appliances and a refrigerator separately. Wiring Diagrams for Multiple Receptacle Outlets - Do-it Wiring for multiple ground fault circuit interrupters (gfci) and standard duplex receptacles are included with protected and non-protected arrangements. Wiring Multiple Outlets in a Series In this diagram wall outlets are wired in a row using the terminal screws to pass voltage from one receptacle to the next. Wire An Outlet The diagram below will show how a standard "Switched" duplex receptacle is wired. In this diagram, both top and bottom receptacles are switched off & on. Take notice that only a 3-wire cable is needed to perform this circuit. Outlet Wiring - Electrical 101 Receptacle Wiring. In the diagram below, a 2-wire NM cable supplies line voltage from the electrical panel to the first receptacle outlet box. The black wire (line) and white (neutral) connect to the receptacle terminals and another 2 wire NM that travels to the next receptacle.