The neutral and ground wires for the circuit are connected to a bar along the side of the service panel box. The neutral and grounding bars in the box may be separate or, in the case of older service panels, the same bar may be used for both purposes.
A special isolated-ground receptacle is require for this circuit and can be identified by the orange color and a small triangle imprinted on the face. When connecting the wires, the isolated ground wire (the red wire pictured here) is marked with green tape or paint on each end and connected to the grounding bar in the service panel, and to the grounding terminal on the receptacle.
Here a switch has been added to control an existing receptacle. The switch takes the hot from the middle receptacles. With this arrangement, all the other receptacles are wired directly to the hot source and the switch controls the middle outlet.
To add a new outlet to a group of receptacles already in place, splice the new wires to one set of wires on one of the existing receptacles. In this diagram each receptacle is wired to the next using the terminals to pass the voltage along. To provide voltage to a new receptacle, remove the wires from one set of terminals on the existing outlet and splice in the new wires and a pigtail back to each terminal.