This arrangement is used for computers and sensitive A/V equipment such as a home theater, to eliminate noise interference in the audio and video output that can be caused by the grounding wires throughout a dwelling’s electrical system.
An isolated-ground receptacle makes use of an extra wire for a separate ground in the circuit. This is the red wire in the 14/3 cable used here which is marked and connected to the grounding terminal on the receptacle. The other cable wires are connected as with any other circuit except for the ground wire. The bare copper ground wire is NOT connected to the receptacle, instead it is connected to the grounding terminal inside the electrical box where the receptacle is housed.
This circuit breaker wiring diagram illustrates installing a 30 amp circuit breaker for a 240 volt circuit. The 10/3 cable for this circuit has 3 conductors and no ground. A 30 amp circuit like this is usually found in water heater circuits and older installations for clothes dryers and kitchen ranges. For a new installation of a kitchen range, use the diagram below for a 50amp circuit.
This diagram illustrates the arrangement for a 20 amp double receptacle circuit with a shared neutral wire. This arrangement is typically used in a kitchen where two appliance circuits are needed in close proximity to each other.