How to check for a bad circuit breaker

Written by billy brainard
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How to check for a bad circuit breaker
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Circuit breakers function as a mechanical fuse in the main service panel that will trip or cut itself off if there is a short or overload in the specific circuit it is wired to. Should one breaker become faulty or cut off, the remaining circuit breakers in the panel will continue to operate. Checking the voltage will help determine if a breaker is faulty or inoperable. Circuit breakers operate off of either 110 volts or 220 volts.

Skill level:
Moderate

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Things you need

  • Screwdriver (Phillips/slotted)
  • Digital multimeter/VOM (volt ohm meter)

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Instructions

  1. 1

    Locate the main circuit panel in the home.

  2. 2

    Verify the circuit breaker in question is in the "on" position. If the breaker has tripped then the lever switch will be halfway in the on and off position, with an orange coloured tab showing in the tiny window on the breaker. Switch the breaker completely off and then back on to reset the breaker. If the breaker immediately trips itself back off, then the breaker is faulty and needs replacing.

  3. 3

    Remove the cover panel from the main circuit panel box. Use the screwdriver to remove each of the screws and set them and the cover to the side.

  4. 4

    Check the voltage on the 110 volt breaker. If the breaker is a single pole, then it should read 110 volts AC. Turn the breaker off. Turn the VOM selector dial to 110v AC. Touch one test probe to the screw on the breaker, and the other test probe to the neutral bus bar. The reading should be zero on the VOM. If you read any voltage, the breaker is faulty and needs replacing. Turn the breaker on. Touch one test probe to the screw on the breaker, and the other test probe to the neutral bus bar. The reading should be 110v. Any other voltage reading means the breaker is faulty.

  5. 5

    Check the voltage on the 220v breaker. If the breaker is a double pole breaker, then it should read 220 volts AC. Turn the breaker off. Turn the VOM selector dial to 220v AC. Touch one test probe to each of the two screws on the breaker. The VOM should read zero volts. Any other reading indicates a faulty breaker. Turn the breaker on. Touch one test probe to each of the two screws on the breaker. The reading this time should be 220v AC. Any other voltage reading indicates a bad or faulty breaker.

  6. 6

    Replace the cover over the main breaker panel box, and insert the screws into each hole. Tighten them down using the screwdriver.

Tips and warnings

  • Use extreme caution when removing the cover panel and avoid touching any of the internal wiring with the panel. Contact with the wiring could result in a serious electrical shock.

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