This wiring diagram illustrates installing a 15 amp circuit breaker for a 120 volt circuit. The 14/2 awg cable for this circuit includes 2 conductors and 1 ground. A 15 amp circuit is usually used for wall receptacle outlets and light fixtures.
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.
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.
It’s not unusual for an old house to have an old doorbell lurking about somewhere that hasn’t worked in years. Fortunately, it’s likely a simple matter to get things back in working order. As illustrated in the above diagram, the parts of an old doorbell circuit include the bell, a button mounted at the door, and a battery somewhere in between the two.