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How to Change a Circuit Breaker

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admin
Date
2017-05-02 17:25
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1285
출처: http://www.wikihow.com/Change-a-Circuit-Breaker

A circuit breaker is connected to an electrical circuit and is designed to stop the power flow though the circuit in the event there is an excessive amperage draw on said circuit. Occasionally, however, these breakers go bad, and you will need to know how to change a circuit breaker. It is highly recommended that you hire a licensed, competent, and insured electrician to perform this task, as electricity can be deadly. However, the steps are outlined below, as some of you readers are simply perusing this article for educational value, and as some may simply get bad advice elsewhere. Follow the steps to learn how to replace a circuit breaker.

Step 1. Find the main circuit breaker box.
Some homes may have 1 large main breaker box as well as smaller branch breaker boxes.
Image titled Change a Circuit Breaker Step 1 Step 2. Locate the defective breaker.
A tripped breaker is halfway between the on and off position.
•••Before assuming a circuit breaker needs to be replaced, try resetting the breaker by turning off all lights and unplugging all devices on that circuit. Then turn the back to the on position.
•••Some breakers must be turned all the way off before they can be turned back on.
•••Test the circuit breaker by turning on the breaker, and then add the devices 1 at a time. If the light or device becomes operable, then a voltage tester is not needed. Image titled Change a Circuit Breaker Step 2Step 3. Use a voltage tester to see if power is going out through the wire attached to the breaker.

Image titled Change a Circuit Breaker Step 3Step 4. Turn off the branch breaker boxes, followed by the main power.


•••This should be the large flip switch located above or below all the other smaller ones. It should also be labeled "main" or something similar. The main breaker typically has the largest amperage rating of all the breakers in the panel.Image titled Change a Circuit Breaker Step 4




Step 5. Turn off the individual breakers.
Image titled Change a Circuit Breaker Step 5
Step 6. Inspect the exterior of the panel.
If there is evidence of rust, charring, discoloration, moisture, or other contamination, DO NOT proceed, and call an electrician immediately.

Step 7. Beware of certain types of panels, specifically those bearing one of the following names:
Federal Pacific Electric, Federal Pioneer, Zinsco, Kearney, GTE Sylvania, or Stab-lok. The safety of these panels is highly debated. Research the issue, and contact an experienced electrician for advise. Decide what to do based upon the information you find.Step 8. Use protective equipment.
Wear insulated lineman's gloves and use insulated lineman's tools. Wear rubber-soled shoes and safety glasses, and stand on a rubber mat.


Step 9Be sure the area around you is safe.
If there is water or another liquid present, do not proceed. Call a licensed electrician immediately. Also, be sure that there is plenty of clearance above, below, to the sides of, and in front of the panel.




Step 10. Remove the screws holding the face plate (called a "dead front") with a Philips screwdriver.
Use the left hand rule when opening the panel to prevent injury in the event of an arc flash.Image titled Change a Circuit Breaker Step 6 Step 11. Read the label on the main power switch to determine what kind of circuit breaker box you own.Image titled Change a Circuit Breaker Step 7Step 12. Inspect (without touching anything) the interior of the panel. 


Look for signs of rust, moisture intrusion, pest intrusion, loose wires, melting, discoloration, charring, heat marking, multiple wires under one screw, aluminum wiring, wiring with damaged insulation, knob and tube wiring, strange modifications, debris, and multiple colored wires connected to each other. If ANY of these conditions are found, or if another type of strange thing is found, do not proceed. Call a licensed, competent, and insured electrician.

Step 13. Loosen the screws that hold the wires found on the defective breaker.


Image titled Change a Circuit Breaker Step 8Step 14. Remove the breaker from the panel.

Image titled Change a Circuit Breaker Step 9

Step 15. Discard the old circuit breaker. 


Image titled Change a Circuit Breaker Step 10




Step 16. Replace the old circuit breaker with the new one.

The replacement breaker must have the same amperage and be the same type (unless using "classified" breakers) as the previous breaker. Snap the circuit breaker back into the same place as the old on the panel.

Image titled Change a Circuit Breaker Step 11



Step 17. Place the wires in the new circuit breaker as they were in the old one.

Image titled Change a Circuit Breaker Step 12



Step 18. Tighten the screws.
Do not over tighten, but do not leave too loose either.

Image titled Change a Circuit Breaker Step 13



Step 19. Replace the circuit panel's faceplate.

If any of the original screws were lost, replace them with FLAT-ENDED MACHINE SCREWS. Using pointed wood screws may damage wiring inside the panel.

Image titled Change a Circuit Breaker Step 14



Step 20. Turn on the main power, followed by the individual breakers.

Image titled Change a Circuit Breaker Step 15



I have reset the breaker but it still does not work. What else should I try?

Sometimes breakers look and feel as if they have been reset, but they really haven't been. Push the switch all the way to the Off position (make sure it clicks), and then push it toward the On position. It should click again. If still nothing happens, you could have a faulty breaker, another tripped breaker upstream, or damaged/disturbed wiring. Also, if the circuit supplies electricity to a GFCI-protected circuit, be sure any GFCI's have been reset.