how to test for a bad circuit breaker



Circuit breakers are an essential component of any electrical system, serving the critical function of protecting the system from damage caused by excessive current. However, like any other electrical equipment, circuit breakers can develop faults over time, and identifying a bad circuit breaker is crucial to ensure the safety and functionality of your electrical system. In this article, we will explore various methods to test for a bad circuit breaker, providing you with the knowledge to troubleshoot and address potential issues effectively.

The Importance of Circuit Breakers

Circuit breakers act as safety devices, interrupting the flow of electrical current when it exceeds a predetermined limit. Without circuit breakers, an electrical system can face severe damage, leading to fire hazards, equipment failure, and even electrocution.

Common Signs of a Bad Circuit Breaker

Before delving into the testing methods, it is essential to identify the signs that indicate a faulty circuit breaker. Recognizing these signs can help you initiate the troubleshooting process promptly. Here are some typical indicators of a bad circuit breaker:

1. Frequent Tripping - If your circuit breaker frequently trips, meaning it shuts off power to a circuit unexpectedly, it could be a sign of a faulty breaker. While circuit breakers are designed to trip occasionally to protect against overcurrent, frequent tripping indicates an underlying issue.

2. Burning Smell - A noticeable burning smell, often accompanied by smoke, is a serious warning sign that your circuit breaker is experiencing problems. This smell could indicate an overloaded or faulty circuit breaker that requires immediate attention.

3. Hot to the Touch - A circuit breaker that feels excessively hot to the touch suggests that it is not functioning correctly. Heat buildup could indicate loose connections or even a faulty breaker.

4. Visible Damage - Physical damage, such as cracks or signs of burning, is an obvious sign of a bad circuit breaker. These visible signs should not be ignored and warrant immediate investigation and action.

Proper troubleshooting and testing can assist in determining if a circuit breaker is indeed at fault. Let's now explore the testing methods in detail.

Visual Inspection

Visual inspection is the first step in the process of identifying a bad circuit breaker. This method allows you to assess the condition of the breaker visually. Here's how you can perform a visual inspection:

Begin by switching off the power to the circuit breaker panel from the main electrical supply. This step ensures your safety while examining the breakers.

1. Inspect for Physical Damage - Thoroughly examine the circuit breaker for any visible signs of damage, such as cracks, burn marks, or melted insulation. Pay close attention to the breaker's case, terminals, and the surrounding area. If any damage is detected, it is crucial to replace the breaker immediately.

2. Check for Loose Connections - Inspect the breaker's connections to ensure they are tight and secure. Loose connections can cause overheating and may indicate a faulty breaker.

3. Look for Burn Marks or Discoloration - Burn marks or discoloration on the circuit breaker, its case, or nearby components can be indicative of overheating or arcing. These signs suggest a faulty breaker that should be replaced.

Using a Multimeter

A multimeter is a versatile tool that allows you to measure various electrical parameters. It can be an invaluable instrument when testing circuit breakers. Follow these steps to test a circuit breaker using a multimeter:

1. Set the Multimeter - Start by setting your multimeter to the AC voltage setting. Ensure that the chosen voltage range is greater than the circuit voltage you intend to test. For instance, if you want to test a 120V circuit, set your multimeter to a range higher than 120V.

2. Check the Voltage - Carefully insert the multimeter probes into the circuit breaker's terminals or jaws. The black probe should go into the breaker's neutral or ground terminal, while the red probe should be connected to the hot terminal. With the breaker on, measure the voltage across the breaker's terminals. If the voltage is within the acceptable range, the breaker is likely functioning correctly. However, if the reading is significantly lower than expected or reads zero, it suggests a bad circuit breaker.

3. Test for Continuity - Continuity testing helps determine if the circuit breaker is carrying current when it should be closed. Begin by switching the breaker off and disconnecting it from the power supply. Set the multimeter to the continuity mode and touch one probe to the breaker's load terminal and the other probe to the line terminal. If the multimeter beeps or indicates continuity, it means the circuit breaker is open and not carrying current when it should be closed. This indicates a faulty breaker that needs replacement.

Using an Ohmmeter

Another method to test a circuit breaker is by using an ohmmeter. This tool measures the electrical resistance of the circuit and can help determine if the breaker is faulty. Here's how to test a circuit breaker using an ohmmeter:

1. Disconnect Power - As with any electrical testing, start by switching off the power to the circuit breaker panel and ensure your safety while conducting the test.

2. Set the Ohmmeter - Set your ohmmeter to the lowest resistance range. This range is typically labeled as "R x 1" or something similar.

3. Probe the Terminals - Touch one ohmmeter probe to the breaker's line terminal and the other probe to the load terminal. A properly functioning breaker should show infinite resistance or "OL" on the ohmmeter's display. If the resistance reads near zero or very low, it indicates a faulty breaker that requires replacement.

4. Observe the Trip Indicator - Some modern circuit breakers are equipped with a trip indicator. This indicator provides a visual or audible signal of a tripped circuit breaker. If your breaker has such an indicator, it can be a helpful tool in identifying a bad circuit breaker.


Testing for a bad circuit breaker is crucial for the safety and efficiency of your electrical system. By recognizing the common signs of a bad breaker and employing reliable testing methods such as visual inspection, multimeter testing, and ohmmeter testing, you can accurately diagnose faulty breakers. Remember that any faulty circuit breaker should be replaced promptly to ensure the continued protection of your electrical system. Regular maintenance and periodic inspection of circuit breakers are essential to prevent potential hazards and ensure the smooth operation of your electrical infrastructure.


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