Home Repair: How to Replace a Circuit Breaker

Breaker boxes control the electrical circuits in a building. Depending on the power needs of the building, the size of the breakers can vary. In most homes, only two sizes of breakers, 120-volt and 240-volt, are used regarding the voltage needs of the equipment and appliances that use the circuit.

The amp needs may have any number of loads specified depending on the wiring used for the circuit. Most of the breakers will have amp loads between 15 and 60. When a breaker fails or needs to be replaced for some other reason, the job is relatively quick and simple as long as safety precautions are used.

Turn off the main breakers.

One of the worst dangers while changing a circuit breaker in your electric control panel is electrocution. With 200 amps and 240 volts coursing through the panel, severe physical harm is a real possibility. To avert personal disaster, turn off the large main breakers. These are usually located at the very top of the panel, but can be at the bottom. If you are unsure about where the main breakers are located, get help rather than risk the danger of opening up your electric panel with the power on.

Remove the cover from the circuit box.

The cover is secured to the breaker box by four or more screws at the corners or along the sides. Carefully set these screws aside as they are removed because you will need them later to fasten the cover back onto the box. Inside the box you will see a maze of wires. When you first see into the circuit box, it may be a bit confusing. Large boxes will have many circuits supported by two or more wires each.

Acquaint yourself with the layout of the box before starting to work inside it.

In most boxes, you will see the large cables coming from the electric meter into the box and attaching to the main breakers. Tracking down from the main breakers will be two metal strips that carry the power to the circuit breakers. You may not be able to see these strips if the box has the maximum number of circuit breakers installed. Each breaker should have one or two wires coming out of it. These are the hot wires.

Along the edge and bottom of the box will be the ground strips.

Most of the screws on the these strips will have wires fastened to them. Every circuit requires at least one hot and one ground wire to function. In most cases, there will also be bare wires attached to the ground strips. These are the neutrals. Replacing a breaker will only require that you work with the wires attached to it.

Locate the correct breaker.

In some boxes, the breakers are attached with screws to the box. However, in most of them, the breakers clip into place. A 120-volt breaker will fasten to one of the power strips. A 240-volt breaker is made to reach across the gap between the power strips and attach to both sides. Make sure that your replacement breaker is compatible with your box and is rated to carry the correct voltage and amp load required for the circuit.

Grip the breaker and pull it loose from the circuit box.

Use a screwdriver to loosen the screw that holds the wire onto the breaker. Be careful not to lose track of the wire. You will need it to be able to attach it to the new breaker. Once one or both of the wires have been removed from the breaker, you are ready to install the new breaker.

If you are replacing a failed breaker, you can just throw it away.

If you are upgrading a breaker to support a different electrical load, you may want to keep the old breaker to use in case a different breaker of the same size fails in the future. Attach the wire or wires to the new breaker and tighten the screws to secure it in place. Insert the new breaker into the slot vacated by the old breaker. Make sure that it clips solidly into the slot or tighten the screw until it feels secure.

Replace the cover onto the breaker box and reinstall the screws.

Make any change that might be necessary to list of breakers on the door of the box. Turn on the main breaker. Turn on the new breaker. Test the circuit to make sure that electricity is flowing to the appliances attached to the it.

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