House Circuit Breaker Wiring Diagrams
–Check local regulations for restrictions and permit requirements before beginning electrical work–
This page contains wiring diagrams for circuit breakers including 15, 20, 30 and 50 amp breakers, as well as a ground fault circuit interrupter breaker. The breaker is installed in a service panel so that it makes contact with one of two hot bus bars that run down the middle of the box.
The hot wire for a circuit is connected to the breaker by a set screw on the base. 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 service panel may be separate or, in the case of older service panels, the same bar may be used for both purposes. Below are diagrams for breaker box wiring branch circuits, gfci breakers, and isolated ground circuits.
Wiring a 15 Amp Circuit Breaker
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.
20 Amp Double Receptacle 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.
20 Amp 240 Volt Appliance Circuit
This circuit breaker wiring diagram illustrates installing a 20 amp circuit breaker for a 240 volt circuit. The 12/2 gauge cable for this circuit includes 2 conductors and 1 ground. A dedicated 20 amp circuit like this is used for heavy household appliances like an air conditioners.
30 Amp Circuit Breaker
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.
50 Amp Circuit Breaker
This circuit breaker wiring diagram illustrates installing a 50 amp circuit breaker for a 240 volt circuit. The 6 gauge cable for this circuit has 3 conductors and 1 ground. A 50 amp circuit like this is used for clothes dryers and new kitchen range installations.
Wiring a GFCI Circuit Breaker
This diagram illustrates wiring for a circuit breaker with a built-in ground fault circuit interrupter. This 20 amp ground fault interrupter breaker is a form of gfci that can be installed at the circuit source. This kind of circuit is used for garbage disposals, whirlpool spas and other locations where water contact is likely.
15 Amp Isolated Ground 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.
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. 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 electrical system.