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Difficulty: EasyProtective Devices

A standard circuit breaker trips and interrupts power to an appliance branch circuit due to an electrical overload. After the fault condition has been resolved, what action is required to restore power to the circuit?

  1. A
    Replace the unit with a new protective device because the internal conductor has permanently melted.
  2. B
    Increase the source voltage to force the internal sensing mechanism to disengage.
  3. Manually reset the breaker operating handle back to the closed (ON) position.Answer
  4. D
    Rewire the branch circuit so the protective device is connected in parallel with the load.

Answer

Manually reset the breaker operating handle back to the closed (ON) position.
Circuit breakers are reusable protective devices engineered with bimetallic strips or electromagnetic coils that open electrical contacts during overcurrent events. Unlike fuses that melt and must be discarded, a circuit breaker simply trips its mechanical latch and can be reset manually to the ON position once the electrical fault is cleared.

Step-by-Step Solution

1
Identify the type of protective device specified in the scenario.
The device is a circuit breaker, which is a reusable electromechanical switch.
Differentiating between sacrificial devices (fuses) and resettable devices (circuit breakers) determines the correct maintenance action.
2
Determine the procedure for restoring an open circuit breaker after a trip.
The internal trip mechanism mechanically separates the contacts, which can be re-engaged by toggling the external handle.
Circuit breakers do not destroy their internal elements during normal tripping and do not need to be replaced.

Key Concept

Circuit Breaker Operation and Resetting
Estimated Time:45s
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Topics

Protective Devices

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