Testing a Bad Circuit Breaker – A Galco Blog Tech Tip

Circuit breakers are safety devices designed to protect electrical circuits and equipment from damaged caused by excess current. In typical cases, an overload or short circuit will trip a breaker to interrupt current flow. This is the expected behavior of the breaker, but in some cases it is important to know how to check the device to determine if the breaker itself is at fault.

Note: when troubleshooting, always make sure to turn off each breaker before removing them from the panel.



First, you should check to see if the breaker has been tripped. If any of the switches are in the OFF position, simply return them to the ON position and try again. If the breaker does not maintain the ON position or it emits a humming sound, proceed to pull the wire out of the circuit breaker and test again. If the breaker is fine, you may have an issue with the wiring rather than the breaker.

If the issue hasn’t been resolved, you should then test the panel. First, remove the wire from the breaker and test the active breaker with a voltmeter. If there is voltage, the breaker is good condition and your problem is most likely in the breaker panel, which may require replacement.

If there is no voltage, proceed with a simple test: run a lightbulb or solenoid voltmeter between the screw and a ground in the panel. If these devices do not run, then the breaker has malfunctioned and will need to be replaced.

A third way to test for a bad breaker is to move its wire to a different breaker and see if the new breaker works. This is generally the simplest and most effective way to test a breaker. Ensure that both breakers are off before moving the wire, and then turn the new breaker on. If the new breaker continues to show a problem, then you most likely have faulty wiring. If the new breaker works fine, then the original breaker has an issue.

One final test you can perform is with an ohmmeter. To do this, you will want to turn the breaker off, remove it from the installation, turn it back on, and then use the ohm meter to check between its screw and bus clip. A reading above 5 ohms indicates that the breaker is faulty and needs to be replaced.

For more about circuit breakers and troubleshooting common faults, contact our experts today!


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