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Testing Circuit Breakers

Circuit breakers are electrical safety devices that are easy to check and reset.
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Many appliances and electronics have fuses that are accessed without opening the housing.

Find the tripped circuit breaker and move it to the ON position.

Power to the people! Fixing electrical things around your home sometimes means going to the source: the electrical power source. That's the electrical service panel where utility wires deliver electricity for distribution to the many circuits in your home. If you've checked the electrical device and the electrical receptacle, but haven't found the problem yet, maybe it's in the service panel, sometimes known as the main. Let's look.

The electrical service panel is the main panel or cabinet through which electricity is brought into the building and then distributed to various branch circuits. Power from the utility company (or your solar power system!) enters the panel through three large wires—two hot or electrified and one neutral. The main neutral wire connects to a neutral bus or common bar, and the two hot mains connect to the main power shutoff, either a large circuit breaker or a pull-out fuse.

Each of the two bars carries 120 volts. All circuit breakers or fuses in the service panel are connected to one or both of these bars. Fuses and breakers rated at 120 volts are attached to a single hot bar; 240-volt breakers or fuses are attached to both hot bars.

Each 120-volt circuit has a black or color wire connected to a circuit breaker or fuse; the white wire is connected to the neutral bus bar. Ground wires also lead to a neutral bar. Power runs through each fuse or breaker and then out of the panel via a hot wire to whatever receptacles, lights, or appliances are on the circuit. White neutral wires bring power back to a neutral bus bar in the service panel, completing the loop, also known as an electrical circuit.

To reset a tripped circuit breaker:
  1. Visually inspect the ends of each circuit breaker in the service panel, looking for one that has its switch leaning toward the OFF side rather than ON. Some circuit breakers, instead, have a red button that can pop out if tripped.
  2. Once you find a tripped breaker, check the circuit index on the inside of the panel to determine what circuit the breaker controls and make sure everything inside the home that's on this circuit is OFF or unplugged.
  3. Reset the circuit breaker switch or button. If it immediately trips, the problem is probably in the circuit's wiring; you'll need an electrician.
  4. Replug any appliances or other electrical devices or turn on lights in the problem circuit to see if they trip the circuit breaker again. If so, the problem is in the device. If not, everything is probably okay.
To test a circuit breaker:
  1. Set the multimeter to "Volts AC" and touch the prongs to the breaker's terminal screw and a ground. If there is no power, the breaker is faulty and requires replacement.
  2. Shut off the MAIN circuit breaker or switch and remove the cover to the electrical service or circuit breaker panel.
  3. Loosen the screws holding the damaged breaker and pull it from the panel. Identify and remove the wires connected to the circuit breaker.
  4. Replace the circuit breaker with one of the exact amperage (15- 20- or 30-amp), attaching the wires into the new breaker. Mount and fasten the replacement circuit breaker. (Some circuit breakers snap into place in the panel while others require screw fasteners.)
  5. Restore power and test the circuit.

Adapted from the new, Interactive Fix-It Club.
Written and illustrated by Dan & Judy Ramsey
Copyright Fix-It Club® © 2003 All Rights Reserved.

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