Circuit breakers can become defective for different reasons. There may be a manufacturer's defect, or they may become ineffective from overuse or abuse. They are designed to be used periodically, in instances when the electrical line that they control is being overloaded and in danger of becoming overheated.
If a line is being overloaded, the breaker will shut off in a neutral position between the on and off settings. It must be reset by pushing it to the off position, then to the on position. This requires a small bit of effort, and a click will be heard when the breaker is reset.
When a larger appliance, such as an air conditioner, is added to a line that serves multiple outlets, the breaker may turn off each time the air conditioner's compressor comes on and other outlets in the line are being used heavily. Constantly resetting the breaker may cause the inner mechanism to wear out, which will keep the entire line without power.
Purchasing a new circuit breaker
Before going to the home improvement store to buy a breaker, look for the number printed on the breaker. This will tell the amp rating that is required. If it is a single breaker ( one switch), the amp rating will be fifteen or twenty. The breaker's amp rating must match that of the breaker that is being replaced.
The breaker must also be made by the same manufacturer as the breaker box, because they are not made for a universal fit. The manufacturer information will be located on the inside of the breaker box door.
Older breakers and breaker boxes may have been made by a manufacturer that no longer sells them or has changed their name, so if you can't find a breaker by that manufacturer, ask a sales clerk. They will probably carry a suitable aftermarket replacement.
Installing a new breaker
The only tools needed are a philips head screwdriver and a flashlight.
You will begin by shutting off the main breaker that controls the flow of electricity to the entire house. Remove the outer cover panel of the breaker box by removing the screws that hold it in place.
A helper may be enlisted to hold the flashlight as you remove the old breaker, because older breakers can occasionally be stubborn to remove while holding a light.
Grasp the breaker from the inside edge (the side that is facing the center of the breaker box) and pull. It should snap out with minimal effort. If not, wiggle it slightly to loosen the grip of the metal clip inside the breaker that holds the breaker in place.
When it is removed, use the philips head screwdriver to remove the black power wire from the end of the breaker. Open the same screw terminal on the new breaker, and place the black wire inside the bracket under the screw. Tighten it until it is secure.
Install the breaker by placing the outer edge (facing the outside of the breaker box) in first, then push the breaker into place until it is parallel with the other breakers. A clicking sound will be heard as it snaps into place.
Replace the cover panel, turn on the main breaker and your new breaker, and the task is complete.
This will only solve the issue of the broken breaker. Solving the problem of an overloaded line will require using fewer electrical components on that line, or adding an additional line from the breaker box. This is a more intricate procedure in electrical repair, and may require the services of a residential electrician.