Main Circuit Breaker Tests. Double Pole 240 Volt Circuit Breaker Test. Single Pole 120 Volt Circuit Breaker Testing with Volt Meter or Digital Multimeter.
How To Test Circuit Breaker
Testing single pole 120 volt or a double pole 240 volt breakers with a voltage tester and taking voltage measurements is the best way to determine if the circuit breaker is bad and if you need to replace any of the homes circuit breakers. When using a volt meter to test circuit breaker always be sure that the setting on the volt meter is higher than the voltage that you will be testing. While I was testing I had my digital multimeter set to the 600 volt scale so as not to damage my voltmeter. I recommend using a digital volt meter when doing a voltage test because they are easier to read. If you don't have one you can get one inexpensively. The circuit breaker test procedures described apply to all brands including Murray, GE-General Electric, Crouse Hinds, Challenger, Cutler Hammer, Square D, ITE, Zinsco, FPE- Federal Pacific, Seimens, Bryant, Sylvania or most any other type of circuit breaker that you believe you are having problems with. When working in a live circuit breaker box be extremely careful. I recommend wearing gloves and long sleeves. Use common sense such as avoiding damp or wet locations. Always use safety procedures and be alert so as not to come in contact with any live surfaces. If you are unsure about troubleshooting these problems get a qualified electrician.
Main Circuit Breaker Tests
Shown in the pictures below is how to take voltage measurements at the homes main circuit breaker to determine if you have 240 volts coming into the circuit breaker panel box. The test points shown in the pictures are across both poles, which should give you 240 volt reading and also testing from one pole of the breaker to the ground buss bar which should give you 120 volt reading on your digital multimeter. You will notice that when I test circuit breaker (s) I wear gloves, it's just a smart thing to do.
Main Circuit Breaker Test Bottom of Double Pole Main Breaker
Main Circuit Breaker Test Top of Double Pole Main Breaker
Double Pole 240 Volt Circuit Breaker Test
Shown in the pictures below is how to test double pole circuit breakers (240 volt) to determine if both poles of the circuit breaker are working. Sometimes one pole of the double pole breaker will stop working causing devices or appliances such as dryer, stove, a/c, heater or water heater to stop operating properly. Testing a homes double pole appliance circuit breaker is the same as testing the main circuit breaker.The testpointsshown in thepictures areacross both poles, which should give a 240 volt reading and also testing from one pole to the ground buss bar should give you a 120 volt reading using your volt meter.
Double Pole Circuit Beaker Test Across Each Pole to Ground
Double Pole Circuit Beaker Test Across Both Poles
As with the main breaker I have tested across both poles and should have a voltage measurement of about 240 volts. From one pole at a time to ground buss bar should give you a voltage measurement of about 120 volts.
Circuit Breaker Single Pole 120 Volt Testing
How To Test 120 Volt Single Pole Circuit Breaker for situations when you either have a circuit breaker that is tripped or you have a circuit that has lost power is a common problem. You can look at the page for a circuit breaker that is tripping for more information. The pictures below show testing a circuit breaker by doing a voltage test from the connection where the wire attaches at the circuit breaker and at the ground buss bar. If you have a circuit breaker that is tripping as soon as you turn it on I suggest that you swap it with one in the homes circuit breaker box that is working properly to rule out a weak circuit breaker. Some circuit breakers can become weak over time causing them to trip at levels below their rated values.
If a test indicates a bad circuit breaker then it is time to replace it. Be sure to take the old circuit breaker with you to match it up.
When you go to remove the breaker for replacement turn off the main circuit breaker on the outside.
Turning off the homes inside main breaker does not kill the power to the inside of the panel box at the main breaker connections. Turn the Power off at the outside main disconnect!
Types of Circuit Breakers
There are basically three types of circuit breakers used in residential application. The first being the standard current overload protection type. These are found in virtually every home. The second being the GFCI Ground Fault Circuit Interrupter type. The GFCI breaker is designed to sense a fault on the safety ground wiring and trip to prevent electrical shock to the user. You don't find many of these anymore as they were expensive and now are replaced by GFCI outlets. These are required by code any where the is a receptacle outlet near water or outdoors. The third type is the Arc Fault sensing circuit breakers. These breakers detect when an electrical arc has occurred and will trip to prevent a fire caused by arcing ans sparks. Say for instance you plug in or unplug something while it is turned on such as a clothes iron. The arc fault breaker senses this and trips. These types of breakers are not seen very often as there are arc fault sensing receptacle outlets that will do the same thing. These are generally required by code in bedrooms.
Test Circuit Breaker with Ohm Meter
With the circuit breaker disconnected and removed from the breaker box. Take the multimeter and place it on the ohms setting. Check from where the breaker attaches to the buss bar to the screw terminal where the wire would connect, doing this with the trip handle in the on position. You should read "0" ohms or what is referred to as a dead short. If the breaker reads anything other than "0" replace it.
All the how to test circuit breaker and voltage check tips on this page apply to site built homes, modular homes as well as mobile homes, manufactured homes and RVs.
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